science learning packet bio b evolution packet

Science Learning PacketBIO B:

Evolution Packet science learning activities for SPS students during the COVID-19 school closure.

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Due to the COVID-19 closure, teachers were asked to provide packets of home activities. This is not intended to take the place of regular classroom instruction but will help supplement student learning and provide opportunities for student learning while they are absent from school. Assignments are not required or graded. Because of the unprecedented nature of this health crisis and the District’s swift closure, some home activities may not be accessible.

If you have difficulty accessing the material or have any questions, please contact your student’s teacher.

Take Home Packet

High School Biology B – Evolution

The goal of Evolution is for students to understand changes in populations of organisms over time. This unit builds on

student’s prior learning, particularly genetics. By the end of the unit, students will be able to predict and explain how

species have changed over time in response to changes in environmental conditions. Students will use multiple lines of

evidence to identify variation in the heritable traits of individuals in a population, ecological factors that influence

survival and reproduction, and the interaction between variation and ecology to produce changes in populations such as

adaptation, speciation, and extinction.

Why should you do this? These materials will help you continue your learning at home. The unit addresses content that is not covered in any other high school science course. Goals are listed for each activity to help you track your learning. Your teacher will provide information on which item(s) will be submitted, when they are due, and how they will be submitted.

This unit is designed to address the following Washington State Science Standards (Next Generation Science Standards): Performance Expectations LS3-3: Apply concepts of statistics and probability to explain the variation and distribution of expressed traits in a population.

LS2-8: Evaluate evidence for the role of group behavior on individual and species’ chances to survive and reproduce.

LS4-1: Communicate scientific information that common ancestry and biological evolution are supported by multiple lines of empirical

evidence.

LS4-2: Construct an explanation based on evidence that the process of evolution primarily results from four factors: (1) the potential for

a species to increase in number, (2) the heritable genetic variation of individuals in a species due to mutation and sexual reproduction,

(3) competition for limited resources, and (4) the proliferation of those organisms that are better able to survive and reproduce in the

environment.

LS4-3: Apply concepts of statistics and probability to support explanations that organisms with an advantageous heritable trait tend

to increase in proportion to organisms lacking this trait.

LS4-4: Construct an explanation based on evidence for how natural selection leads to adaptation of populations.

LS4-5: Evaluate the evidence supporting claims that changes in environmental conditions may result in (1) increases in the number of

individuals of some species, (2) the emergence of new species over time, and (3) the extinction of other species.

   Science and Engineering Practices: Constructing Explanations, Developing and Using Models Crosscutting Concepts: Systems and System Models, Structure and Function

What resources do I need? This packet, a pencil or pen, and scrap paper. You may find it useful to have a highlighter and markers or colored pencils, but this isn’t required. We recommend that you call a friend to talk through the lessons and/or share your learning with someone in your household.

What about online resources? This packet references several videos and websites that you can access with a phone. If you don’t have internet access on your phone, you may find it helpful to call or text a friend to ask questions. If this is not possible, just skip those suggestions and use the materials in the packet.

What resources do I have to be successful?

If you can access Schoology, your teacher may be providing resources on their class webpage. If not, everything you

need is in this packet. You can also ask questions of your teacher by sending them an email or contacting them using

their usual procedure.

https://www.nextgenscience.org/pe/hs-ls3-3-heredity-inheritance-and-variation-traits

https://www.nextgenscience.org/pe/hs-ls2-8-ecosystems-interactions-energy-and-dynamics

https://www.nextgenscience.org/pe/hs-ls4-1-biological-evolution-unity-and-diversity





Timeline:

This packet will take 2-3 weeks to complete. Below we have provided a suggestion on how you might work through the

materials. Your teacher may provide a modified version of this schedule on their Schoology page. Please adjust for you

/ your family.

Unit Driving Question: How does the environment impact species over time? How will species change or adapt?

Lesson Name Extensions 1 Evolution Initial Ideas

Make an entry in the Discussion on your teacher’s Schoology page (if provided)

00 Learning Tracking Tool

Video – Stated Clearly: What is Evolution?

2.1 Malaria and SCD Demo

Start 2.1 Malaria and SCD Reading and Worksheet

Finish 2.1 Malaria and SCD Reading and Worksheet

2.2 Malaria and SCD - Evolution Tool



3.1 Rules We Learned from SCD 3.1 OPTIONAL Evolution Lecture with Sean Carroll

3.2 Comparing Models


Video – Stated Clearly: What is Natural Selection?

4 Introduction to Human Evolution

Start 4 Human Evolution Activities Worksheet

Finish 4 Human Evolution Activities Worksheet


Explore the videos and interactives from PBS’s series Your Inner Fish

5.1 Investigating Skin Pigmentation

5.1 Skin Pigment Questions

5.2 Skin Pigmentation – Evolution Tool

00 Learning Tracking Tool entry


6.1 Explaining Other Examples Video – Stated Clearly: Does The Theory of Evolution really matter?

6.1 OPTIONAL Introduction to Geologic Time

PBS Deep Time Interactive

HHMI Making of Mass Extinctions interactive timeline

Videos – PBS Eons

6.2 Student Self-Assessment

Catch-Up Day (or explore the extensions)

https://www.youtube.com/watch?v=GhHOjC4oxh8&list=PLInNVsmlBUlQT_peuWctrmGMiLngK-6fb&index=3&t=0s

https://www.youtube.com/watch?v=GhHOjC4oxh8&list=PLInNVsmlBUlQT_peuWctrmGMiLngK-6fb&index=3&t=0s

https://www.youtube.com/watch?v=0SCjhI86grU&list=PLInNVsmlBUlQT_peuWctrmGMiLngK-6fb&index=4&t=0s

https://www.youtube.com/watch?v=0SCjhI86grU&list=PLInNVsmlBUlQT_peuWctrmGMiLngK-6fb&index=4&t=0s

http://www.pbs.org/your-inner-fish/home/

https://www.youtube.com/watch?v=hqepQGOYKZ0&list=PLInNVsmlBUlQT_peuWctrmGMiLngK-6fb&index=5&t=0s

https://www.youtube.com/watch?v=hqepQGOYKZ0&list=PLInNVsmlBUlQT_peuWctrmGMiLngK-6fb&index=5&t=0s

https://www.pbs.org/wgbh/evolution/change/deeptime/index.html

http://media.hhmi.org/biointeractive/click/extinctions/?_ga=2.249023426.438836521.1553713826-44292177.1553713826

http://media.hhmi.org/biointeractive/click/extinctions/?_ga=2.249023426.438836521.1553713826-44292177.1553713826

https://www.pbs.org/show/eons/

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The videos and interactives suggested can be easily located with a Google search.

Name: _____________________________________________ Class: __________________________

Learning Tracking Tool for Evolution: How does the environment impact species over time? How will species change or adapt?

Lesso

n

What did we do? What did we figure out?

Summarize key information and activities with a description and/or

picture.

How can our learning be used to explain the phenomenon?

Describe what you will you add to your explanation of the phenomenon.

Self-Assess:

Where am I with my understanding of the

phenomenon?

(Example: Ready to explain, starting to get it, need more information)

What questions do I have?

What additional information do you need

to understand the phenomenon?

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How to use this PowerPoint• Work at your own pace. Your health and your family come first.

• If possible, you might find it helpful to go through activities at the same time as a peer. Then you can communicate through text, email, or a call if you have questions or to share ideas.

• You might find it helpful to have a piece of scrap paper and a pencil or pen to record questions or ideas.

• Read through the slides one at a time. Take your time to explore the images and any links.

• If you come across something you don’t understand, make a note of which slide you are on and come back to it after you go through the whole PowerPoint. If you are still confused, feel free to email your teacher with a question. You could also ask someone in your household or reach out to a peer through text, email, or a call.

• When you finish, consider sharing what you learned with someone in your household or a friend through text, email, or a call. Explaining your thinking will help you to retain and make sense of the information.

1 Evolution Initial IdeasHow does the environment impact species over time?

How will species change or adapt?

Goals

After reviewing this PowerPoint, you should be able to:1)Define “evolution.”2)Define “scientific theory” and explain why evolution is not

“just a theory.”3)Identify several things that you notice from a video and

several questions that you have about how Sickle Cell Disease evolved and persisted in populations.

Warm Up – Answer on a sheet of scrap paper

1. What do you think “evolution” means?

2. What do you think of when you hear the word “evolution”?

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What is evolution?

Evolution is the change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes that are passed on from parent to offspring during reproduction.

Evolution is the process by which different kinds of living organisms are thought to have developed and diversified from earlier forms during the history of the earth.

Evolution as a scientific theory Watch this video to learn more about the terms “theory” and “law.”

A scientific theory is an explanation of an aspect of the natural world that can be repeatedly tested and verified in accordance with the scientific method, using accepted protocols of observation, measurement, and evaluation of results.

What is the evidence for evolution?The theory of evolution by natural selection is supported by evidence from comparative anatomy, embryology/development, the fossil record, DNA, and the geographic distribution of species on Earth.

Comparative AnatomyScientists compare structures to identify organisms that may share a common ancestor or to identify species that independently evolved similar structures to survive in their environment.

Embryology/DevelopmentScientists identify patterns in the development of organisms from a single cell into complex multicellular organisms. Think back to the Genetics: Development Unit!

Fossil RecordScientists use fossils to understand when and where species evolved and the relationships between species.

Video: “What is a fossil?

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https://www.youtube.com/watch?v=P30QlwSsUic

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Geographic Distribution of SpeciesPolar bears live only at the North Pole and penguins only at the South Pole.

Australia is home to a lot of marsupial mammals, including many that look like placental mammals that live elsewhere on Earth.

DNAScientists compare the DNA of species.

Check out this video to learn more about the evidence for evolution.

Evolution Unit Driving Questions

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How does the environment impact species over time?

How will species change or adapt?

Video: Sickle Cell Disease and Malaria

Make a T-chart to record your notes:What I notice: What I wonder:

••••

••••

What did we learn about the evolution of Sickle Cell Disease?

On the Schoology Discussion Board for Lesson 1 create a post to share your learning and ideas:

1. List as many learnings as you can.

2. What questions do you have about the evolution of Sickle Cell Disease?

3. How do you think this might relate to things you learned previously about genetics and inheritance?

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https://www.youtube.com/watch?v=Zsbhvl2nVNE

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You will use your understanding of Ecology and Genetics to investigate and explain how species evolved:

Evolution Three QuestionsVariation: What differences are there among individuals in the population?

Ecology: What factors affect the survival and reproduction of individuals in the population?

Interactions between Variations and Ecology: What changes have occurred in the population? (over time or in different areas)

Check Your Understanding1)Define “evolution.”2)Define “scientific theory” and explain why evolution is not “just a

theory.”3)Identify several things that you notice from a video and several

questions that you have about how Sickle Cell Disease evolved and persisted in populations.

What’s Next?

1. Post to the Discussion board on your teacher’s Schoology page (if provided).

2. Make a new entry in your Learning Tracking Tool titled “1 Evolution Initial Ideas.”

3. Consider watching the optional video – Stated Clearly: What is Evolution?

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https://science.howstuffworks.com/life/evolution/question609.htm What is a fossil?

A fossil of a Microraptor from a 130-million year old forest that existed in what is now Liaoning Province,

China is displayed at the American Museum of Natural History in New York City. GETTY IMAGES

The term fossil describes a wide range of natural artifacts. Generally speaking, a fossil is any

evidence of past plant or animal life that is preserved in the material of the Earth's crust. But

when most people talk about fossils, they mean a specific subsection of this group -- fossils in

which the shape of the animal or plant has been preserved, while the actual organic matter of

its body is gone. These amazing remnants, which date to prehistoric times, were formed very

slowly by dynamic geological processes.

In most cases, the fossilization process began when a plant or animal died and was quickly

covered with sediments, usually at the bottom of a body of water. The loose sediments

protected the bodily remains from the elements, bacteria and other forces that cause

weathering and decay. This slowed the decaying process down so that some of the remains

(in most cases, only hard material like bone or shell) were preserved for thousands of years.

During this time, sediment layers continued to collect above the bone. Eventually, these

sediment layers became hard, solid rock.

Sometime after this hard rock layer formed, water percolated down through the rock and

washed the preserved remains away. Since the rock above was hard and rigid, it didn't fall

down into the empty space where the remains used to be. This empty space formed a natural

mold of the animal, perfectly preserving the shape of the original remains.

https://science.howstuffworks.com/life/evolution/question609.htm

http://news.discovery.com/fossils/

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Reading alternative for fossil video

In some cases, percolating water carried minerals into the mold. These minerals hardened to

make a natural cast of the form, just as an artist might make a sculpture cast by filling a mold

with plaster. All the original organic material disappeared, but nature left a precise mineral

reproduction of the plant or animal remains. In cases where minerals did not fill the mold,

paleontologists may fill it themselves, creating an artificial cast.

This is just one scenario of fossil creation, of course -- there are all sorts of other ways nature

might form a fossil. A lot of prehistoric insects, for example, have been fossilized in amber.

This sort of fossilization occurred when the insect was enveloped in the liquid sap from a tree.

Just like the sediments at the bottom of a body of water, the sap material protected the insect

from decay and eventually hardened. Animal fossils are also found in tar pits, bogs, quicksand

and volcanic ash.

Another interesting fossil type is petrified wood. Petrified wood generally forms when trees

fall into a river, where they become saturated and then buried in mud, ash, silt and other

materials. Minerals, such as the silica in volcanic ash, seep into the tree and fill in tiny pores in

wood's cells. This changes the overall composition of the wood, turning it into stone material,

while preserving its original structure. The variety of minerals in petrified wood creates striking

vivid colors.

In addition to fossilized plant and animal bodily remains, paleontologists study fossilized

animal footprints and trails, and even fossilized animal dung (called coprolite). These fossils

are enlightening because they reveal something about how prehistoric animals moved and

what they ate.

The fossil record, the total collection of fossils in the world, is extraordinarily important to our

understanding of the Earth's history. Fossils tell us which plants and animals existed in

prehistoric times, and where they lived. They also tell us something about when they lived.

Based on the position of fossils in the layers of the Earth's crust, paleontologists can

determine which animals predate other animals and which animals lived at the same time.

Using carbon dating, paleontologists can sometimes estimate the age of fossils. This provides

the age of the rock layer where the fossil was found, which helps scientists date all the other

material at that level. Without fossils, we would have a much more incomplete picture of

Earth's early history.

https://science.howstuffworks.com/life/evolution/volcano.htm

https://science.howstuffworks.com/life/evolution/carbon-14.htm

The Making of the Fittest: Natural Selection in Humans

[NARRATOR:] Davaun and Skyy Cooper are brother and sister. Both of them have sickle cell

anemia. Before the advent of modern medicine, sickle cell anemia almost certainly meant death

before adulthood. Even today, young patients can suffer strokes and organ failure. Sickle cell

anemia is a genetic disease. Parents of those who have the disease might not have it themselves,

but both must carry the sickle cell character in their DNA. Besides some bone pain, Skyy leads

the fairly normal life of a 13 year-old girl. But her younger brother Davaun, has suffered acute

chest syndrome and has already had his spleen removed.

[NARRATOR:] Skyy and Davaun's symptoms arise from the fact that some of their red blood

cells become misshapen--crescents instead of discs--preventing enough oxygen from being

delivered to all parts of the body. It's not completely clear why symptoms are variable, but what

is most perplexing about sickle cell disease is that it is not rare.

[DR. HEENEY:] So, in the United States, we think there are between 70,000 and 125,000

persons with sickle cell disease. However, that doesn't take into account immigration and other

patients or persons coming from other parts of the world into the country.

[NARRATOR:] In fact, in some populations--African Americans, for example--the incidence

is as high as 1 in 500, astoundingly high for a deadly inherited disease. Didn't Darwin teach us

that harmful traits disappear from the gene pool through natural selection? Why is sickle cell

anemia so prevalent, and why in particular among people of African descent? The answers to

these questions began with a remarkable set of observations from an unlikely person more than

sixty years ago.

[NARRATOR:] Tony Allison has spent most of his career as a medical doctor and molecular

biologist in the U.S. and England. But he grew up in East Africa and he is quick to recall his

formative years in Kenya.

[DR. ALLISON:] We lived in the upcountry, and we used to go to the coast every year in

August for the holiday when it was a little bit cooler than at other times. So we had the trip all

the way down, which was usually with a truck and a car. And, so we would camp on the way

and, in Tsavo and there would be lions roaring around, so it was really quite exciting.

[DR. CARROLL:] These are the infamous Tsavo lions--

[DR. ALLISON:] The famous--

[DR. CARROLL:] Right?

[DR. ALLISON:] infamous Tsavo lions--

[DR. CARROLL:] Around 1950, biologists didn't know a lot about the details of evolution,

because we didn't know really how heredity worked. The structure of DNA had not been

discovered yet, genetic code had not been cracked. So, we know that while evolution was due

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Transcript for Sickle Cell Disease and Malaria video in 1.1

to genetic changes, we didn't know how those genetic changes took place whatsoever. So, there

were holes in the whole picture of the evolutionary process, and Tony Allison was probably the

least-likely person you would imagine, who would fill one of the most critical holes. He grew

up far away from the centers of science in Europe and North America. He was really interested

in natural history and he loved the Kenyan wildlife, and he visited archeological digs that were

going on at the time. But it was a really circuitous and serendipitous route that led him to an

enormous discovery in evolutionary biology.

[NARRATOR:] Tony first went to University in South Africa where he studied physical

anthropology, then to medical school at Oxford. He had a deep interest in human origins, but

not so much in ancient stones and bones. Tony was interested in blood. Could the common

ABO blood types say anything about the evolutionary history of East African tribal people?

[DR. ALLISON:] And I actually learned just before going out about the sickle cell condition.

Nobody really knew the frequencies of sickle cells in East Africa. So it was a barren slate, so to

speak.

[NARRATOR:] Blood samples from people carrying the sickle cell character appear quite

normal--until oxygen is removed. Tony learned that adding a chemical agent to the samples

would quickly reduce oxygen and reveal sickle cells, if they were there. This gave him an easy

test to score blood samples for the sickle cell character.

[DR. ALLISON:] But what was striking was that you had high frequencies of people carrying

the sickle cell character in the coast and near Lake Victoria, and very low frequencies in the

high country in-between, in Nairobi.

[NARRATOR:] What could possibly account for such a striking disparity? The sickle cell

character was understood to be genetic, not environmental. Tony had grown up in the dry

Kenyan highlands, but he knew the warm, moist lowlands were a breeding ground for the

anopheles mosquito that carried the malaria parasite, Plasmodium falciparum.

[DR. CARROLL:] And it dawned on him, the places where there was a really high incidence

of sickle cell was where there was a really high incidence of malaria. Bang.

[NARRATOR:] Now it was a burning question that confronted Tony: could sickle cell and

malaria be connected? And if so, how? It was a radical notion that a genetic disease could

somehow be connected to an infection.

[DR. CARROLL:] When you went back to Oxford--you had this idea of a linkage between

sickle cell and malaria, but you hadn't published it? Did you know it was a big deal? I mean, did

you...

[DR. ALLISON:] I was sure it was a big deal. Yes. That's why I wanted not to go off half-

cocked. I wanted to have a really complete story.

[DR. CARROLL:] So, he decided he had to sit on this idea until he got a chance to test it

properly. So… and a key element of the scientific method is, to come up with a hypothesis,

that's great. But you've got to test it in every way possible to see whether or not it can hold up to

that sort of scrutiny. That's how science moves forward.

[DR. ALLISON:] The scientific method essentially means that you address a problem and try

to find a solution. So you look at children of the appropriate age and find out whether they are,

in fact, protected against malaria. And if that's the case, you predict that you will have high

frequencies of sickle cells only in areas where malaria is endemic.

[DR. CARROLL:] He wanted to know that this correlation held, not just in Kenya, but

everywhere.

[NARRATOR:] It would be important to look directly at the incidence of malaria and sickle

cell in as many areas as possible. So, Tony went on a sickle-cell safari.

[DR. CARROLL:] He wanted to gather blood samples from all over East Africa to really test

this correlation. And now he was a trained medical doc, so he had something to offer. So he

would go into the market on market day, and offer to do checkups on children. And just take a

little finger prick or a little heel prick to get a little sample of blood.

[NARRATOR:] The first thing he did was look at the malaria parasite load in each sample.

Then he tested for the sickle cell character. He found that children carrying the character had a

lower parasite count, as if they were partially protected against malaria.

[DR. CARROLL:] And when he examined the blood of about 5,000 individuals, a really

massive study, the correlation was really clear. So clear, in fact, that he could really draw a map

of East Africa, and shade in the areas of high incidence of sickle cell, and they were

superimposed right on top of the areas of high incidence of malaria. Bang, that was it.

[NARRATOR:] The many samples and detailed maps made it clear there was a connection

between sickle cell and malaria. But to understand how sickle cell might protect people from

malaria required thinking about the genetics of sickle cell.

[DR. ALLISON:] What happens is the genes are lined up on chromosomes. And one has pairs

of them with the exception of the sex chromosomes. And this means that you have two copies.

So the copies can be the same or they can be different. And if they're the same, they're called

homozygous. And if they're different, they're called heterozygous.

[NARRATOR:] When an individual finds a partner and reproduces, one of each pair of

chromosomes is passed on. If the parents are both heterozygous, carrying one sickle cell and

one normal gene, odds are one in four that the child will be sickle cell homozygous, two in four

that the child will be heterozygous, and one in four that the child will carry two copies of the

normal gene. In the absence of malaria, there is strong selection against the sickle cell gene.

However, in a malarial environment, individuals born with two copies of the sickle cell gene,

and those born with two copies of the normal gene, are both at a disadvantage. One gets sickle

cell disease, the other is most vulnerable to malaria. Tony's brilliant insight was that those that

carried just one sickle cell gene had an innate resistance to malaria. Malaria tipped the selective

balance in favor of heterozygotes. The evolutionary trade-off is that protection from malaria

comes at the cost of more sickle cell disease in the population. The sickle cell mutation was not

the best genetic solution you might imagine to resist malaria. That's not how evolution works. It

was the most available--a simple typo, A to T, in the gene that encodes hemoglobin.

[DR. CARROLL:] Mistakes are made in the copying of DNA in every generation. You and I

were born with about 40 or 50 mutations that didn't exist in either of our parents. It's just part of

the nature of copying three billion letters in the process of reproduction. And when those

mistakes arise, a typo arises in the globin gene... for most of us, that would be a bad thing. But

if you live in a malarial area, it gives you an edge against the malarial parasite, so that mutation

is retained.

[DR. ALLISON:] Well, fitness, essentially, is a measure of whether a particular gene is likely

to be passed on to the next generation. And this means that for that to happen, the individual

carrying that gene has to survive to reproductive age, and secondly has to reproduce.

[DR. CARROLL:] Now you had a sense that you had this explanation that was general to the

prevalence of sickle cell and its correlation with malaria. But you didn't quite know the

mechanism, right?

[DR. ALLISON:] That's right.

[DR. CARROLL:] So what did you do next?

[DR. ALLISON:] Well [laughs] I have to say I left that part of the story to others, because it's

quite a complex story...

[NARRATOR:] A large body of subsequent research has shown that the sickle cell mutation

compromises the ability of the parasite to reproduce. Thus, a mutation that creates one genetic

disease can also protect against another disease.

[DR. CARROLL:] What Tony gave us was a fully-worked-out example of evolution by

natural selection. And the amazing thing was, this was in humans. This is how natural selection

was working on humans in real time in the real world. Tony's map of East Africa was a

stunning achievement. But he could go further than that. He knew that there was a high

incidence of sickle cell in Southern Europe, in Southern India, and in other parts of Africa. And

it turns out, these were all malarial zones as well. And so, his map applied not just to East

Africa, but that whole part of the world.

[DR. HEENEY:] When I'm explaining about the origins of sickle cell disease and its

association with malaria to children or their families, they often look at me with incredulity.

They don't understand, like, "You're kidding, right? This is all to do with a mosquito infection?"

As our species has been able to move across the globe to areas with low malarial incidence, this

gene is now really more of a nuisance than anything else. It's not really a clear selective

advantage for them, in Boston, let's say. But it takes thousands of years for the population to

change and for genetics to change based on the pressures around them in the environment.

[NARRATOR:] What Tony Allison did, first with his sharp intuition and then with his

rigorous research, will stand as a monument, bringing our own evolutionary process into the

light.

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2.1 Malaria and Sickle Cell Disease Demo

How does a fatal disease persist in a population?

GoalsAfter reviewing this PowerPoint, you should be able to:1)Explain how populations evolve (NOT

individuals).2)Describe evolution using the term “allele

frequency.”3)Analyze allele frequency data related to malaria

and Sickle Cell Disease.

Background: Evolution and Allele Frequencies

Video: “What is an allele?”

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Imagine a population of beetles. Beetles come in green and brown.

Evolution is change in allele frequenciesbecause alleles (DNA) produce heritable traits

What alleles are present in the gene pool?How does the frequency of alleles change

over generations?

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Malaria and Sickle Cell Disease Demo

1) Read and answer the questions on the first page of the “Malaria and SCD Reading and Worksheet.”

2) Then review the data on the following slides and answer the questions on the back of the worksheet.

3) In Lesson 2.2 you will explain the evolution of Sickle Cell Disease in areas with high and low levels of malaria.

1: Parent PopulationThere are two parts to this demo, Simulation 2 and Simulation 3. In both cases, the population starts as the “Parent Population” shown below.Answer these questions on your worksheet / paper:a) Identify the three genotypes for the gene that codes for

hemoglobin subunits in the parent population. What are the starting frequencies for each genotype?

b) What are the start allele frequencies for the A and S alleles?

Simulation 2: Environment with no malaria

The table below shows the genotypes and phenotypes of the first generation of offspring in an environment where there is little to no malaria.

Simulation 2: Environment with no malariaThe table below shows the genotypes and phenotypes of the second generation of offspring in an environment where there is little to no malaria.Answer these questions on your worksheet / paper:c) How did the frequencies of the A and S alleles change

over time? What are the trends?d) Explain the trends using your knowledge of Sickle Cell

Disease.

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Analyze the graph and answer the question below:

Simulation 3: Environment with malaria

The table below shows the genotypes and phenotypes of the first generation of offspring in an environment where high rates of malaria infections occur.Remember to compare this to the Parent Population!

Simulation 3: Environment with malariaThe table below shows the genotypes and phenotypes of the second generation of offspring in an environment where high rates of malaria infections occur.Answer these questions on your worksheet / paper:e) How did the frequencies of the A and S alleles change

over time? What are the trends?f) Explain the trends using your knowledge of Sickle Cell

Disease.

Analyze the graphs and answer the questions below:

g) Summarize the trend for each genotype (AA, AS, SS) in Simulation 2 and Simulation 3.

h) Do you think the trends will continue for Simulation 3? Explain why or why not.

13 14

15 16

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Check Your Understanding1) Identify several things that you notice from a video and

several questions that you have about Sickle Cell Disease.

2) Develop an initial model for how a fatal disease persists in a family.

3) Add details to your model at the organism, cellular, and atomic-molecular scales.

What’s Next?1) Look back at the predictions you made about what

would happen in the demo. Were your hypotheses supported or not supported by the data? Explain.

2) Check your work using the provided key.

17

Name: ___________________________________________________________ Period: ____________

Malaria and Sickle Cell Disease Reading and Worksheet

Introduction:

In the United States, about 1 in 500 African-Americans develops Sickle Cell Disease. In Africa, about 1 in 100 individuals

develops the disease. Why is the frequency of a potentially fatal disease so much higher in Africa?

The answer is related to another potentially fatal disease, malaria. Malaria is characterized by chills, fever, vomiting and

severe headaches. Anemia and death may result. Malaria is caused by a protozoan parasite (Plasmodium) that is

transmitted to humans by the Anapheles mosquito. When malarial parasites invade the bloodstream, the red cells that

contain defective hemoglobin become sickled and die, trapping the parasites inside them and reducing infection.

Compared to AS heterozygotes, people with the AA genotype (normal hemoglobin) have a greater risk of dying from

malaria. Individuals with the AS genotype do not develop Sickle Cell Disease and have less chance of contracting malaria.

They are able to survive and reproduce in malaria-infected regions. Therefore, BOTH the A and S alleles of these people

remain in the population. SS homozygotes have Sickle Cell Disease, which usually results in early death.

In a region where malaria is prevalent, the S allele confers a survival advantage on people who have one copy of the

allele, and the otherwise harmful S allele is therefore maintained in the population at a relatively high frequency. This is

the phenomenon that you will be exploring today.

The frequency of the S allele in malaria-infected regions of Africa is 16%, the sickle cell allele (S) is also widespread in the

Mediterranean and other areas where malaria is or used to be a major threat to life. In contrast, the S allele frequency is

only 4% in the United States, where malaria has been virtually eliminated. Compare the regions where Malaria is still a

threat with the sickle cell rates in those areas:

What do you notice?

Demo:

Hypothesis/Prediction: What do you think will happen to the frequencies of A and S alleles as a result of the presence of

malaria? (Will the frequency of A increase or decrease? What about S?

In areas with high malaria…. In areas with low malaria…

Answer the following questions as you review the slides with malaria and SCD demo data:

1: Parent Population

a) Identify the three genotypes for the gene that codes for hemoglobin subunits in the parent population. What

are the starting frequencies for each genotype?


Simulation 2: No Malaria

c) How did the frequencies of the A and S alleles change over time? What are the trends?

d) Explain the trends using your knowledge of Sickle Cell Disease.

Graph: Provide two explanations for why the S allele persists after 5 generations.

Simulation 3: Malaria is present

e) How did the frequencies of the A and S alleles change over time? What are the trends?

f) Explain the trends using your knowledge of Sickle Cell Disease.

Graphs:



Look back at the predictions you made about what would happen in the demo. Were your hypotheses supported or not

supported by the data? Explain.

Name: _______________________KEY____________________________________ Period: ____________

Malaria and Sickle Cell Disease Reading and Worksheet

Introduction:

In the United States, about 1 in 500 African-Americans develops Sickle Cell Disease. In Africa, about 1 in 100 individuals

develops the disease. Why is the frequency of a potentially fatal disease so much higher in Africa?

The answer is related to another potentially fatal disease, malaria. Malaria is characterized by chills, fever, vomiting and

severe headaches. Anemia and death may result. Malaria is caused by a protozoan parasite (Plasmodium) that is

transmitted to humans by the Anapheles mosquito. When malarial parasites invade the bloodstream, the red cells that

contain defective hemoglobin become sickled and die, trapping the parasites inside them and reducing infection.

Compared to AS heterozygotes, people with the AA genotype (normal hemoglobin) have a greater risk of dying from

malaria. Individuals with the AS genotype do not develop Sickle Cell Disease and have less chance of contracting malaria.

They are able to survive and reproduce in malaria-infected regions. Therefore, BOTH the A and S alleles of these people

remain in the population. SS homozygotes have Sickle Cell Disease, which usually results in early death.

In a region where malaria is prevalent, the S allele confers a survival advantage on people who have one copy of the

allele, and the otherwise harmful S allele is therefore maintained in the population at a relatively high frequency. This is

the phenomenon that you will be exploring today.

The frequency of the S allele in malaria-infected regions of Africa is 16%, the sickle cell allele (S) is also widespread in the

Mediterranean and other areas where malaria is or used to be a major threat to life. In contrast, the S allele frequency is

only 4% in the United States, where malaria has been virtually eliminated. Compare the regions where Malaria is still a

threat with the sickle cell rates in those areas:

What do you notice?

There is an overlap

between regions where

malaria is present and

regions with high frequencies

of the hemoglobin S allele for

sickle cell.

Demo:

Hypothesis/Prediction: What do you think will happen to the frequencies of A and S alleles as a result of the presence of

malaria? (Will the frequency of A increase or decrease? What about S?

In areas with high malaria…. In areas with low malaria…

Hypothesis – no right or wrong answers! Hypothesis – no right or wrong answers!

Answer the following questions as you review the slides with malaria and SCD demo data:

1: Parent Population

a) Identify the three genotypes for the gene that codes for hemoglobin subunits in the parent population. What

are the starting frequencies for each genotype?

AA – 25% AS – 50% SS – 25%


A – 50% S – 50%

Simulation 2: No Malaria

c) How did the frequencies of the A and S alleles change over time? What are the trends?

The A allele increased in frequency from 50% to 81% while the S allele decreased in frequency from 50% to 19%

d) Explain the trends using your knowledge of Sickle Cell Disease.

Having the genotype SS results in Sickle Cell Disease, which may affect an individual’s ability to survive and

reproduce. This would result in a decrease in the amount of S alleles in the population because individuals with

A alleles would be more likely to pass on their DNA.

In the absence of malaria, there is no benefit to having the S allele.

Graph: Provide two explanations for why the S allele persists after 5 generations.

First, there may not have been enough time for the allele to be completely eliminated from the population. Many

more generations may be required. Second, in simulation 2, even though individuals with the sickle cell disease

genotype (SS) were 100% selected against, individuals who were heterozygous (AS) had neither a selective

advantage nor a selective disadvantage. The S allele can “hide” in the heterozygotes from generation to generation

and persist in the population.

Simulation 3: Malaria is present

e) How did the frequencies of the A and S alleles change over time? What are the trends?

From the parent generation to the first generation the frequency of S alleles goes down from 50% to 32% and the A

allele goes up from 50% to 68%. However, in the second generation the S allele increase from 32% to 39% and the A

allele decrease from 68% to 61%.

f) Explain the trends using your knowledge of Sickle Cell Disease.

In an environment with malaria, there is still a disadvantage to having the genotype SS as those individuals get Sickle

Cell Disease and may not survive to reproduce. However, having the genotype AS offers protection from malaria.

AS individuals have an advantage over AA and SS. Having some S alleles in the population would be helpful.

Graphs:


In Simulation 2 AA genotypes increased in frequency while AS genotypes decreased. SS individuals did not survive.

In Simulation 3 AA genotypes initially went up, but then declined slightly from the starting amount. AS genotypes

went up steadily. SS individuals did not survive.


Based on the data from simulation 3 and what we know about Sickle Cell Disease and malaria, it seems likely that

the allele frequency of the S allele will stabilize somewhere between 30 and 50%, which is higher than the frequency

of S alleles in the population without malaria (Simulation 2). Having too many S alleles would result in more

individuals getting SS and having Sickle Cell Disease, but having too few would mean more susceptibility to malaria.

Look back at the predictions you made about what would happen in the demo. Were your hypotheses supported or not

supported by the data? Explain.

Answers will vary.

Name: ________________________________ Period: ____

Evolution Tool: Malaria and Sickle Cell Disease Demo

EcologyWhat factors affect the

survival and reproduction of individuals in the

population? (selective forces)

VariationWhat differences are there between individuals in the

population? Identify heritable traits that impact survival.

Tim

e 1

Tim

e 2

Tim

e 3

Gene PoolHow will the frequency of alleles

change in the population over time?

Interactions between variation and ecology:

What changes have occurred in the

population?

Tim

e 1

Tim

e 2

Tim

e 3

Ecology

Variation

Interactions between variation and

ecology:

Malaria is present in the environment

Malaria is not presentin the environment

75% A25% S

75% A25% S

Malaria

Malaria

Sickle Cell Disease

AA(normal

hemoglobin)

Individuals with AA genotypes do not get

SCD, but they are susceptible to malaria

Explain the evolution of Sickle Cell Disease using the Evolution Three Questions:

Variation: What differences are there among individuals in the population?



Name: ________KEY______________________ Period: ____

Evolution Tool: Malaria and Sickle Cell Disease Demo


survival and reproduction of individuals in the

population? (selective forces)



Tim

e 1

Tim

e 2

Tim

e 3





population?

Tim

e 1

Tim

e 2

Tim

e 3

Ecology

Variation


ecology:

Malaria is present in the environment

Malaria is not presentin the environment

50% A50% S

50% A50% S

Malaria

Sickle Cell Disease

Sickle Cell Disease

AA(normal

hemoglobin)

Individuals with AA genotypes do not get

SCD, but they are susceptible to malaria

AS(Sickle Cell Trait

/ Carrier)

SS(Sickle Cell

Disease)

Individuals with AS genotypes do not have

SCD symptoms and they are resistant to malaria

Individuals with SS genotypes have SCD and

may not survive to reproduce

68% A32% S

61% A39% S

70% A30% S

81% A19% S

AA(normal

hemoglobin)

AS(Sickle Cell Trait

/ Carrier)

SS(Sickle Cell

Disease)

Individuals with AA genotypes do not get SCD

Individuals with AS genotypes do not have

SCD symptoms

Individuals with SS genotypes have SCD and

may not survive to reproduce

Explain the evolution of Sickle Cell Disease using the Evolution Three Questions:




Answer should include:

Variation: AA, AS, and SS genotypes

Ecology: Malaria and Sickle Cell Disease limit the ability of individuals to survive and reproduce. In regions with malaria, AS individuals have an advantage due to resistance to malaria. In areas without malaria both AA and AS individuals survive and outcompete individuals with SS genotypes.

Interactions: In areas with malaria there will be a higher frequency of S alleles in the population since having the genotype AS offers a survival advantage. In areas without malaria there is no benefit to the S allele and those with the genotype SS will suffer from Sickle Cell Disease. For this reason, there will be a low frequency of S alleles in the population.

Name: Evolution Unit

Rules from SCD: What have we learned about how populations change?

SEP: Constructing Explanations CCC: Patterns Cause and Effect

Variation

Ecology:

Reproduction

Ecology:

Competition

Ecology:

Differential Reproductive Success

Interactions between variations and ecology lead to…

Change in population over time

Name: Why don’t antibiotics work like they used to?

Rules from bacteria: What have we learned about how populations change?

SEP: Constructing Explanations CCC: Patterns Cause and Effect

Variation Individuals have the genotypes AA, AS, or SS for hemoglobin. Those who are AA have normal hemoglobin, AS have Sickle Cell Trait and don’t typically show symptoms (except under oxygen stress), and SS have Sickle Cell Disease and experience symptoms that may result in premature death without treatment. This is a heritable trait determined by DNA.

Ecology:

Reproduction Humans reproduce through sexual reproduction (meiosis and fertilization). Each parent passes on 1 of their 2 alleles for each gene.

Ecology:

Competition Humans compete for food, water, shelter, and space just like other organisms.

Ecology:


When malaria is present in the environment, individuals with the genotype AS are best able to survive. When malaria is not present, AA individuals also survive (and there is no advantage to the S allele). SS individuals suffer from Sickle Cell Disease and may not survive to reproduce. Those best able to survive and compete for resources will reproduce and pass on their DNA.

Interactions between variations and ecology lead to…


In environments with malaria, the S alleles offers an advantage to those with the genotype AS, so the S allele will survive in the population at a medium-low frequency. In environments without malaria there is no advantage to having the S allele and its frequency will be low.

Sean Carroll Evolution Lecture Guided Notes – Endless Forms Most Beautiful Watch the lecture: https://www.youtube.com/watch?v=g6tROZ2hLE8

1. What was Darwin’s academic life when he was young?

2. What are two geological concepts that Darwin used to mold his understanding of biology?

3. What was Darwin’s first great theory about Coral Reef?

4. What were a couple of discoveries that interested Darwin as he explored South America?

5. What were some of the organisms that interested Darwin on the Galapagos Islands (~19min)?

6. How did these observations combine with his knowledge of geology?

7. Why did Darwin hide his research on species formation?

8. How did Darwin’s breeding of pigeons aid in his analysis of the finches?

9. What does the model “life as a tree” suggest about where all different species come from?

10. What is “descent with modification” (~31min)?

11. What did Darwin mean by the broken branches “filled the Earth”? What are some examples?

https://www.youtube.com/watch?v=g6tROZ2hLE8

jmwilson

Text Box

3.1 OPTIONAL Evolution Lecture with Sean Carroll

12. What were the four main ideas from the fossil record?

13. How did species change over time according to Darwin?

14. What are the three ingredients of evolution?

15. What is the genetic variation of the rock pocket mouse?

16. Why does this variation make a difference in survival or the rock pocket mouse?

17. What leads to the black coloration? Is it common in mice (~45min)?

18. How can an allele spread quickly through a population?

19. Summarize the concept of natural selection and its effect on populations.

20. How do mutations arise?

21. Why are homozygous dominant mice slightly different than heterozygous mice?

22. Summarize your ideas about evolution by natural selection from this lecture.

23. What are two questions you have about evolution by natural selection?

These materials were developed with funding through a grant from the Gordon and Betty

Moore Foundation to Northwestern University and the University of Colorado Boulder. This work is licensed under a Creative Commons Attribution 4.0 License: http://creativecommons.org/licenses/by/4.0/ 1

Name: ________________________________________ Period: _______ Date: ________

Comparing Evolution Models

Scientists often compare models and evaluate the strengths and weaknesses of each. We have spent some time developing a model for how Sickle Cell Disease evolves in environments with and without malaria. It is time to compare our model to that of two scientists who came before us-Charles Darwin and Jean Baptiste de Lamarck.

Procedure: Get out your “Rules We Learned” worksheet for comparison. Then read the article on the next page summarizing Darwin and Lamarck’s theories and complete the two columns below.

Lamarck’s Theory Darwin’s Theory

Variation

Ecology:

Reproduction

Ecology:

Competition

Ecology:



http://creativecommons.org/licenses/by/4.0/



Two Other Models: Jean Baptiste de Lamarck’s vs. Charles Darwin’s

Jean Baptiste de Lamarck (1744-1829) and Charles Darwin (1809-1882) both developed theories over their

careers. They both had theories to explain the variation of life on Earth. Their theories had similarities and

differences. Both Darwin and Lamarck believed that life on Earth changed over time and was still changing.

They both believed that populations adapted become more suited for survival in their environments and that

life on Earth started with fewer, more simple organisms and has developed into many more complex

organisms.

Lamarck published his theory to explain the similarities and differences of life on Earth in the book, Theory of

Inheritance of Acquired Characteristics in 1801. In this, Lamarck said that if an organism changes during its

lifetime in order to adapt to its environment, those changes are then passed on to its offspring. He said that

change is driven by what organisms want or need. For example, Lamarck believed that elephants all used to

have short trunks. When there was no food or water that they could reach with their short trunks, some

elephants stretched their trunks to reach the water and branches. Then because they now had developed a

little bit longer trunk through stretching than other elephants, their offspring would inherit long trunks. Lamarck

also said that body parts that are not being used, such as the human appendix and little toes are gradually

disappearing. He claimed that eventually, people will be born without these parts.

Darwin, on the other hand, published his theory in On the Origin of Species in 1859. In his theory, he said that

the desires of animals have nothing to do with how they evolve, and that changes in an organism during its

lifetime do not affect the traits it passes on to its offspring, and do not affect the evolution of a species. He said

that organisms, even of the same species, are all different and that some will happen to have heritable

variations that give them a competitive advantage in their environments to survive more often and have more

offspring. The offspring then are born with these trait variations that give them a competitive advantage for

survival and reproduction. As more and more of them survive and reproduce, individuals with that trait

makeup more and more of the population. Other individuals, that are not so well adapted to this environment,

die off. Most elephants used to have short trunks, but some few had longer trunks. When there was no food or

water that they could reach with their short trunks, the ones with short trunks died off, and the ones with long

trunks survived and reproduced. Eventually, most of the elephants alive today have long trunks.

Making Sense: Which model is more similar to ours (Lamarck’s or Darwin’s)? Explain.

___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________




Name: ________________________________________ Period: _______ Date: ________

Comparing Evolution Models

Scientists often compare models and evaluate the strengths and weaknesses of each. We have spent some time developing a model for how bacteria populations have changed over time to become more resistant to antibiotics and it is time to compare our model to that of two scientists before-Charles Darwin and Jean Baptiste de Lamarck.

Procedure: Complete the first column of the table filling in each of the rules we developed from bacteria. Then, read the article on the next page summarizing Darwin and Lamarck’s theories and complete the other two columns.

Our Model Lamarck’s Theory Darwin’s Theory

Variation Elephants have short and long trunks.

Elephants have short and long trunks.

Ecology:

Reproduction

Individual elephants stretch their trunks over their lifetime, making them longer. They pass on these longer trunks to their offspring.

Some elephants are born with longer trunks (heritable trait).

Ecology:

Competition

Elephants compete for resources such as food, water, shelter, and space.

Elephants compete for resources such as food, water, shelter, and space.

Ecology:


The elephants with longer trunks were better able to reach resources such as food and water. They survive and reproduce more than elephants with shorter trunks.

The elephants with longer trunks were better able to reach resources such as food and water. They survive and reproduce more than elephants with shorter trunks.


If there is an advantage to having a longer trunk, over time the percentage of elephants with longer trunks in the population will increase.

If there is an advantage to having a longer trunk, over time the percentage of elephants with longer trunks in the population will increase.




Two Other Models: Jean Baptiste de Lamarck’s vs. Charles Darwin’s

Jean Baptiste de Lamarck (1744-1829) and Charles Darwin (1809-1882) both developed theories over their

careers. They both had theories to explain the variation of life on Earth. Their theories had similarities and

differences. Both Darwin and Lamarck believed that life on Earth changed over time and was still changing.

They both believed that populations adapted become more suited for survival in their environments and that

life on Earth started with fewer, more simple organisms and has developed into many more complex

organisms.

Lamarck published his theory to explain the similarities and differences of life on Earth in the book, Theory of

Inheritance of Acquired Characteristics in 1801. In this, Lamarck said that if an organism changes during its

lifetime in order to adapt to its environment, those changes are then passed on to its offspring. He said that

change is driven by what organisms want or need. For example, Lamarck believed that elephants all used to

have short trunks. When there was no food or water that they could reach with their short trunks, some

elephants stretched their trunks to reach the water and branches. Then because they now had developed a

little bit longer trunk through stretching than other elephants, their offspring would inherit long trunks. Lamarck

also said that body parts that are not being used, such as the human appendix and little toes are gradually

disappearing. He claimed that eventually, people will be born without these parts.

Darwin, on the other hand, published his theory in On the Origin of Species in 1859. In his theory, he said that

the desires of animals have nothing to do with how they evolve, and that changes in an organism during its

lifetime do not affect the traits it passes on to its offspring, and do not affect the evolution of a species. He said

that organisms, even of the same species, are all different and that some will happen to have heritable

variations that give them a competitive advantage in their environments to survive more often and have more

offspring. The offspring then are born with these trait variations that give them a competitive advantage for

survival and reproduction. As more and more of them survive and reproduce, individuals with that trait

makeup more and more of the population. Other individuals, that are not so well adapted to this environment,

die off. Most elephants used to have short trunks, but some few had longer trunks. When there was no food or

water that they could reach with their short trunks, the ones with short trunks died off, and the ones with long

trunks survived and reproduced. Eventually, most of the elephants alive today have long trunks.

Making Sense: Which model is more similar to ours (Lamarck’s or Darwin’s )? Explain.

___________________________________________________________________________ Darwin’s model is more similar to ours because he said that evolution acts on existing variation in the population which is produced by heritable traits. Individuals do not pass on acquired traits. ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________


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4 Human EvolutionHow did humans evolve?

Goals

After reviewing this PowerPoint, you should be able to:1)Describe what you learned from a video about the

evolution of bipedalism.2)Describe an aspect of human evolution (closely related

species, changes in anatomy, and/or how climate change impacted human evolution).

Video:Ancient Human Ancestors: Walking in the Woods

Make a T-chart for notes:What I notice: What I wonder:

••••

••••

1 2

3 4

jmwilson

Text Box

https://www.youtube.com/watch?v=CrebQed8b2Q

4/28/2020

2

Human Evolution Activities

Choose at least 2 of the activities to explore and complete:Activity 1 – Our Family TreeActivity 2 – BipedalismActivity 3 – Climate Change and Human EvolutionActivity 4 – Hominin Species

Follow the directions and answer the questions on the provided worksheet. Additional resources are provided on the slides that follow.

Activity 1 – Our Family Tree Resources from Biology for a Changing World ©

Mill

ions

of y

ears

ago

DNA similarities between species

Activity 2 -Bipedalism

5 6

7 8

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Activity 3 – Climate Change and Human EvolutionHuman Evolution Timeline at humanorigins.si.edu/evidence/human-evolution-timeline-interactive

Activity 4 – Hominin SpeciesHuman Evolution Timeline at humanorigins.si.edu/evidence/human-evolution-timeline-interactive

Check Your Understanding

1)Describe what you learned from a video about the evolution of bipedalism.

2)Describe an aspect of human evolution (closely related species, changes in anatomy, and/or how climate change impacted human evolution).

What’s Next?1) Make a new entry in your Learning Tracking Tool titled “4

Human Evolution.”2) Consider exploring the videos and interactives from PBS’s series

Your Inner Fish

9 10

11

jmwilson

Text Box

http://www.pbs.org/your-inner-fish/home/

What Was "Lucy"? Fast Facts on an Early Human Ancestor

By National Geographic Staff

PUBLISHED SEPTEMBER 20, 2006

Perhaps the world's most famous early human ancestor, the 3.2-

million-year-old ape "Lucy" was the first Australopithecus afarensis

skeleton ever found, though her remains are only about 40 percent

complete (photo of Lucy's bones).

Discovered in 1974 by paleontologist Donald C. Johanson in Hadar,

Ethiopia, A. afarensis was for about 20 years the earliest known

human ancestor species.

WHAT DID LUCY LOOK LIKE?

With a mixture of ape and human features—including long dangling

arms but pelvic, spine, foot, and leg bones suited to walking

upright—slender Lucy stood three and a half feet (107 centimeters)

tall.

Recreations based on other A. afarensis skulls later found nearby reveal an apelike head with a

low and heavy forehead, widely curving cheekbones, and a jutting jaw—as well as a brain

about the size of a chimpanzee's.

WHY WAS LUCY NAMED LUCY?

Inspired by repeated playings of "Lucy in the Sky With Diamonds" at a celebratory party on the

day the specimen was found, researchers gave it the Beatles' mod

moniker.

HOW DO WE KNOW LUCY WAS FEMALE?

Lucy's size gives her away as a female. Later fossil discoveries

established that A. afarensismales were quite a bit larger than

females.

WAS LUCY AN ADULT?

A number of factors point to Lucy being fully grown. For one thing,

her wisdom teeth, which were very humanlike, were exposed and

appear to have been in use for a while before her death. In

addition, the sections of her skull—separated in children—had

grown together.

jmwilson

Text Box

Reading Alternative for "Walking in the Woods" video in Lesson 4

Name: ____________________________________________ Period: ____________

Human Evolution Activities

Activity 1 – Our Family Tree

1. How closely related are you to other primates: a chimpanzee, an orangutan, an Old World Monkey,

and a prosimian? What does DNA evidence indicate about relatedness?

2. Two populations are considered separate species when they no longer interbreed (reproduce).

Consider what you have learned about evolution. How would primate species evolve over time?

3. What group/genus are modern humans a part of? (Hint: Our species name is _______ sapiens.)

4. What are the names of the other groups of hominids in the human family tree?

Activity 2 – Bipedalism

4. How did hominids change as they became bipedal?

a. spine

b. pelvis/hips

c. limbs (arms and legs)

Activity 3 – Climate Change and Human Evolution

Go to the Human Evolution Timeline at humanorigins.si.edu/evidence/human-evolution-timeline-interactive

Click on the “Climate Fluctuations” section. This should pop up some purple bars at the top. Click on

these to learn more about climate fluctuations over the course of human evolution.

5. Summarize for yourself: How has the climate changed and fluctuated over the past 8 million years?

http://humanorigins.si.edu/evidence/human-evolution-timeline-interactive

Click on the blue “Major milestones in human evolution” circles at the bottom.

6. Identify several adaptions of human ancestors to their environment. How did they survive?

Activity 4 – Hominin Species


Click on the red bars in the species section.

Species Where did it live? When did it live? Notes (What are some interesting facts

about this species?)

Au

str

alo

pith

ecu

s

afr

ica

nu

s

Au

str

alo

pith

ecu

s/P

ar

an

thro

pu

s b

ois

ei

Hom

o e

rectu

s

Hom

o

ne

an

de

rth

ale

nsis


Name: _____________Key_______________________________ Period: ____________

Human Evolution Stations

Station 1 – Our Family Tree

1. How closely related are you to other primates: a chimpanzee, an orangutan, an Old World Monkey,

and a prosimian? What does DNA evidence indicate about relatedness?

Humans are most closely related to chimpanzees. We are next most closely related to an orangutan,

Old World Monkey, and most distantly to a prosimian. The DNA evidence shows that our DNA is

98.2% similar to a chimpanzee and 96.3% similar to an orangutan. This supports the idea that we

are more closely related to chimpanzees.

2. Two populations are considered separate species when they no longer interbreed (reproduce).

Consider what you have learned about evolution. How would primate species evolve over time?

Over time primates would have mutations that created variations. These variations might have

helped primates to survive in different locations or to use different types of resources such as eating

different foods. This could result in two different populations. Over generations those populations will

become more and more different.

3. What group/genus are modern humans a part of? (Hint: Our species name is _______ sapiens.)

Homo

4. What are the names of the other groups of hominids in the human family tree?

Paranthropus, Australopithecus, Ardipithecus

Station 2 – Bipedalism

4. How did hominids change as they became bipedal?

a. spine

Became “S”-shaped, skull/spine connection moved forward on the skull

b. pelvis/hips

Changed from long and narrow to bowl-shaped

c. limbs (arms and legs)

The arms changed from being longer than the legs to being shorter than the legs. The

angle of the femur changed from angling out to angling in.

Station 3 – Climate Change and Human Evolution


Click on the “Climate Fluctuations” section. This should pop up some purple bars at the top. Click on

these to learn more about climate fluctuations over the course of human evolution.

5. Summarize for yourself: How has the climate changed and fluctuated over the past 8 million years?

Overall the climate has cooled over the past 8 million years. Climate fluctuations increased about 6

million years ago. There were wet and dry periods and changes in vegetation. Our brain size

increased the most during the period of greatest fluctuation.


Click on the blue “Major milestones in human evolution” circles at the bottom.

6. Identify several adaptions of human ancestors to their environment. How did they survive?

Humans became bipedal and increased in brain size. We also learned to use tools, fire, and

agriculture. These adaptations helped our species to survive changes in climate.

Station 4 – Hominin Species


Click on the red bars in the species section.

Species Where did it live? When did it live? Notes (What are some interesting facts about this species?)

Au

str

alo

pith

ecu

s a

fric

an

us

Southern Africa (South

Africa)

About 3.3 to 2.1

million years ago

Au. africanus was anatomically similar to Au. Afarensis (“Lucy”) with a combination of human-like and ape-like features. Compared to Au. afarensis, Au. africanus had a rounder cranium housing a larger brain and smaller teeth, but it also had some ape-like features including relatively long arms and a strongly sloping face that juts out from underneath the braincase with a pronounced jaw. Like Au. afarensis, the pelvis, femur (upper leg), and foot bones of Au. africanus indicate that it walked bipedally, but its shoulder and hand bones indicate they were also adapted for climbing.

Au

str

alo

pith

ecu

s/P

ara

nth

rop

us b

ois

ei

Eastern Africa

(Ethiopia, Kenya,

Tanzania, Malawi)

About 2.3 to 1.2

million years ago

Like other members of the Paranthropus genus, P. boisei is characterized by a specialized skull with adaptations for heavy chewing. A strong sagittal crest on the midline of the top of the skull anchored the temporalis muscles (large chewing muscles) from the top and side of the braincase to the lower jaw, and thus moved the massive jaw up and down. The force was focused on the large cheek teeth (molars and premolars). Flaring cheekbones gave P. boisei a very wide and dish-shaped face, creating a larger opening for bigger jaw muscles to pass through and support massive cheek teeth four times the size of a modern human’s. This species had even larger cheek teeth than P. robustus, a flatter, bigger-brained skull than P. aethiopicus, and the thickest dental enamel of any known early human. Cranial capacity in this species suggests a slight rise in brain size (about 100 cc in 1 million years) independent of brain enlargement in the genus Homo.


Ho

mo

ere

ctu

s

Northern, Eastern, and

Southern Africa;

Western Asia (Dmanisi,

Republic of Georgia);

East Asia (China and

Indonesia)

Between about 1.89

million and 143,000

years ago

Early African Homo erectus fossils (sometimes called Homo ergaster) are the oldest known early humans to have possessed modern human-like body proportions with relatively elongated legs and shorter arms compared to the size of the torso. These features are considered adaptations to a life lived on the ground, indicating the loss of earlier tree-climbing adaptations, with the ability to walk and possibly run long distances. Compared with earlier fossil humans, note the expanded braincase relative to the size of the face. The most complete fossil individual of this species is known as the ‘Turkana Boy’ – a well-preserved skeleton (though minus almost all the hand and foot bones), dated around 1.6 million years old. Microscopic study of the teeth indicates that he grew up at a growth rate similar to that of a great ape. There is fossil evidence that this species cared for old and weak individuals. The appearance of Homo erectus in the fossil record is often associated with the earliest handaxes, the first major innovation in stone tool technology. Early fossil discoveries from Java (beginning in the 1890s) and China (‘Peking Man’, beginning in the 1920s) comprise the classic examples of this species. Generally considered to have been the first species to have expanded beyond Africa, Homo erectus is considered a highly variable species, spread over two continents (it's not certain whether it reached Europe), and possibly the longest lived early human species - about nine times as long as our own species, Homo sapiens, has been around!

Ho

mo

ne

an

de

rth

ale

nsis

Europe and Southwest

to Central Asia

About 400,000 -

40,000 years ago

Neanderthals (the ‘th’ pronounced as ‘t’) are our closest extinct human relative. Some defining features of their skulls include the large middle part of the face, angled cheek bones, and a huge nose for humidifying and warming cold, dry air. Their bodies were shorter and stockier than ours, another adaptation to living in cold environments. But their brains were just as large as ours and often larger - proportional to their brawnier bodies. Neanderthals made and used a diverse set of sophisticated tools, controlled fire, lived in shelters, made and wore clothing, were skilled hunters of large animals and also ate plant foods, and occasionally made symbolic or ornamental objects. There is evidence that Neanderthals deliberately buried their dead and occasionally even marked their graves with offerings, such as flowers. No other primates, and no earlier human species, had ever practiced this sophisticated and symbolic behavior. DNA has been recovered from more than a dozen Neanderthal fossils, all from Europe; the Neanderthal Genome Project is one of the exciting new areas of human origins research.

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5.1 Introduction to the Evolution of Human Skin Pigmentation

How can we explain the patterns of human skin pigmentation seen around the world using what we

know about evolution?

Goals

After reviewing this PowerPoint, you should be able to:1)Identify several things that you notice from a video and

several questions that you have about the evolution of human skin pigmentation.

2)Describe how pigment molecules are produced in the skin.3)Why are folate and vitamin D important?4)Describe how skin pigmentation is related to levels of UV

light in a region.

Video: Biology of Skin Pigmentation


••••

••••

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3 4

jmwilson

Text Box

https://www.hhmi.org/biointeractive/biology-skin-color

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Use the following infographics to answer the questions on the provided worksheet.

Evolution of Skin Pigmentation Infographics from Biology for a Changing World ©

Intense UV light destroys folate

Vitamin D is produced in skin exposed to UV

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7 8

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Check Your Understanding1)Identify several things that you notice from a video and several

questions that you have about the evolution of human skin pigmentation.

2)Describe how pigment molecules are produced in the skin.3)Why are folate and vitamin D important?4)Describe how skin pigmentation is related to levels of UV light in a

region.What’s Next?1) Finish the worksheet, if you haven’t already.2) In Lesson 5.2 you will explain the evolution of human skin

pigmentation.

9 10

[crickets chirp]

[cymbal plays]

[chime plays]

[music plays]

[JABLONSKI (narrated):] Human brains are gray. Human blood is red. Our bones are off-white. Doesn’t

matter where you’re born or to whom. But human skin is different.

[music plays]

Some of us have rich dark brown skin; some of us have pinkish white skin. Most of us are somewhere

in between. For the longest time, why this variation exists was a real scientific mystery … that opened

the door for some to invest this biological trait with moral value, and then use that to justify the

suffering of others.

[elephant trumpets]

But biological traits aren’t good or bad. They’re features that have evolved because they enhance an

organism’s odds of surviving and passing on its genes.

[JABLONSKI:] Like other animal traits, the sepia rainbow of human skin color evolved through natural

selection. Now, thanks to advances in anthropology and genetics, exactly how and why it did is no

longer a mystery.

[music plays]

[background discussion]

[JABLONSKI:] Biological anthropologists like myself spend our lives studying how humans evolved, and

why we differ from one another physically.

[music plays]

[JABLONSKI (narrated):] Our skin provides one of the most visible markers of human variability. It’s

something that sets us apart from our closest animal relatives. Under their dark fur, chimpanzees have

pale skin, and millions of years ago that was probably also the case for the primates that were our

common ancestors. So where did humanity’s range of skin colors come from?

From physics we know that the color of any object comes from the wavelengths of light that it reflects

back to an observer’s eye. We see leaves as green because they reflect back the wavelengths our eyes

see as green, absorbing the wavelengths we see as other colors like blue or red.

In humans, different wavelengths of light are reflected or absorbed by a pigment in the top layer of our

skin. That pigment’s called melanin. It sits inside what look like tiny grains—the melanosomes—that

are produced by cells called melanocytes.

Our individual genetic inheritance determines the type of melanin inside our melanosomes. The

reddish-yellow pheomelanin is more abundant in lightly pigmented people. More darkly pigmented

people have more of the brown-black eumelanin, and the more eumelanin, the darker the skin.

Melanin also colors human and animal hair, and the feathers of many birds.

[JABLONSKI:] Interestingly, the wavelengths of light that melanin reflects are far less important

biologically than the ones it actually absorbs. And of the ones it absorbs, the ones that are the most

important are those that we can’t even see.

[music plays]

[JABLONSKI (narrated):] Much of the light given off by the sun is invisible to our eyes. Some of that is

what’s called ultraviolet radiation, which is highly energetic. So much so, it can actually penetrate living

cells. When it does, it can wreak havoc within them. It can even cause mutations in skin cell DNA. What

stands between us and that threat is the melanin in our skin.

[crowd noise]

[ABDEL-MALEK:] Melanin is kind of like a sensor; it’s kind of like a guardian molecule. And its main job

is protection.

[JABLONSKI (narrated):] For instance, by forming what are called supranuclear caps and absorbing UV.

[ABDEL-MALEK:] They’re like little parasols around the nucleus. And UV cannot penetrate these to go

and attack the DNA.

[JABLONSKI (narrated):] That’s just one of the things molecular biologist Zalfa Abdel-Malek finds

remarkable about melanin. Another is the broad range of benefits it provides a diverse collection of

species.

[ABDEL-MALEK:] We know that melanin in lower vertebrates is important for regulating body

temperature. It can also give animals camouflage. And allows them to recognize other members of the

species to propagate the species.

[JABLONSKI (narrated):] In humans, one of melanin’s functions is clearly to protect cells from UV

damage. As we evolved, we lost hair and increased melanin production in our skin. So, is there a

connection between the intensity of UV radiation and skin color?

[JABLONSKI:] Hi, Tess.

[JABLONSKI (narrated):] I first became fascinated with UV and skin color in the 1990s.

[pages turning]

But as I searched for information about the global distribution of solar UV, I discovered the available

data was in fact quite spotty.

[paper rustling]

I began casting a wider net and almost by accident found exactly the raw data needed to fix that. It

hadn’t been collected by anyone interested in my questions, but rather by NASA.

[rocket engine roars]

[MISSION CONTROL:] Ignition.

And liftoff.

[JABLONSKI (narrated):] In the 1980s, concern about the health risk posed by the depletion of UV-

blocking atmospheric ozone led NASA to take millions of UV measurements from space. I asked NASA

to send me the data, and then asked my geographer husband, George Chaplin, to try to visualize it.

It turned out to be a bigger request than I’d realized, but he found a way to turn all those data points

into a map, … a map that showed for the very first time exactly how UV exposure varies throughout

the world.

[CHAPLIN:] This is the map.

[JABLONSKI (narrated):] Most striking was the clear gradient between the equator and the poles,

which was interrupted only in places where altitude increased UV exposure …

[CHAPLIN:] This is actually in the Tibetan plateau …

[JABLONSKI (narrated):] … and persistent cloud cover decreased it.

[CHAPLIN:] … the Congo Basin. So it’s full of humidity and moisture, which is blocking the UV.

[JABLONSKI (narrated):] Solar energy is a fundamental attribute of any environment. And it’s a well-

established fact that organisms living at different latitudes adapt in some way to their local solar

conditions. To see how closely human skin color correlates with UV exposure, I collected skin pigment

measurements made by anthropologists studying indigenous peoples.

[JABLONSKI:] For many years, anthropologists have faced the challenge of how to accurately measure

skin color. We now use this little device called a reflectometer. Basically, it sends out light of specific

colors, and then it measures the amount of light that is reflected back. This tells us what color Tess’s

skin is, and we can then compare this to people all over the world.

[JABLONSKI (narrated):] George then created a second map, using measured skin colors and

environmental data. It showed UV intensity does indeed predict skin color. Wherever UV is strong, skin

is dark, like it is near the equator or at high altitude. At the poles, the skin of indigenous people is

almost always lighter. That suggests that variation in human skin melanin production arose as different

populations adapted biologically to different solar conditions around the world.

[JABLONSKI:] As we’ve noted, our early ancestors probably had full body hair covering pale skin, just

like other primates. So when did the darker shades of human skin begin to evolve?

[sea gulls calling]

[JABLONSKI (narrated):] DNA sequencing has made it possible to find evidence that can help answer

that question. Rick Kittles is a geneticist who’s skilled at deciphering such clues.

[KITTLES:] Whenever a species undergoes some form of selection, some form of natural selection,

evidence of that selection is found in the genome. And so, as geneticists, we get really excited when

we explore the genome for these signatures. One way in which that’s done is by sampling worldwide

populations and looking throughout the genome at variation and comparing across populations. And

it’s a very exciting process, I feel like a detective when I go through that process.

[music plays]

[JABLONSKI (narrated):] One of the many genes that genetic detectives have linked to human

pigmentation is called MC1R. Sampling from around the world indicates there’s a fair amount of

variation in the DNA sequence of that gene. But not from every corner of the globe.

[KITTLES:] When we look at MC1R within African populations, we don’t see a lot of diversity. And the

particular allele that they have in those African populations is the one that codes for darker skin. MC1R

codes for a protein which is involved in the switch from the production of pheomelanin to eumelanin.

And we know pheomelanin is the reddish-yellow pigment, and then the eumelanin is the brown-black

pigment.

[children talking]

[JABLONSKI (narrated):] The absence of MC1R diversity in African populations indicates that, in that

part of the world, there is strong negative selection against any alleles that would alter dark skin. And

how long has this allele been fixed in African populations? Other genetic studies have calculated that it

has been as much as 1.2 million years. Since our species evolved in equatorial Africa, it’s reasonable to

conclude that, by that time, all humans were dark-skinned.

[JABLONSKI:] The fossil record supports what we’ve gleaned from genetic evidence. But here’s where

we confront what was, for me, the heart of the mystery.

[JABLONSKI (narrated):] The evolution of dark skin in humans suggests that, under strong UV light,

that trait provided a survival advantage. So what exactly was that advantage? It’s certainly true UV

damage to skin cell DNA can lead to cancer, and skin cancer can be fatal. For a long time, that seemed

the likeliest explanation. Except …

[JABLONSKI:] Skin cancer generally develops after a person’s peak reproductive years. For that reason,

though it might cut your life short, it’s unlikely to affect your ability to pass on your genes.

[JABLONSKI (narrated):] As I was struggling to conceive of an alternative explanation, I happened to

attend a lecture on severe birth defects.

[pages turn]

That talk was about a research project that had found evidence that certain birth defects are far more

common among pregnant women with diets deficient in a B vitamin called folate. Only weeks before,

I’d come across a paper that described how strong sunlight breaks down folate circulating in skin blood

vessels. Here was a direct link between UV radiation, skin color, and reproductive success. It was a

small “eureka” moment for me.

In the years since, we’ve learned that folate is not only essential for normal embryonic development,

it’s even needed for healthy sperm production in males.

[JABLONSKI:] Folate is biological gold. It is an essential nutrient, and it needs to be protected from UV

radiation as it circulates in the blood vessels in the skin. That is what melanin does.

[JABLONSKI (narrated):] I felt I was halfway home on my quest to understand human skin color

variation. But a big question remained:

[JABLONSKI:] Why aren’t we all dark skinned?

[JABLONSKI (narrated):] It turns out there’s another side to our relationship with UV light. UV light is

not all bad. In fact, the small portion of it known as UVB is critical for the synthesis in our bodies of

vitamin D—a process that starts in the skin. Without vitamin D, humans cannot absorb calcium from

our diet, to build our bones and for a healthy immune system. Back when all of our ancestors lived

close to the equator, there was no problem getting enough UVB through dark skin to make the vitamin

D needed. But then some populations started moving north, where the UV striking the Earth’s surface

is much weaker.

[JABLONSKI:] In northern latitudes, dark skin makes it hard to produce the vitamin D that human

bodies really need.

[JABLONSKI (narrated):] The consequences of vitamin D deficiency include rickets—a bone

development disease that can cripple the young. In higher latitudes with less UV, the selective pressure

on MC1R that produced dark skin in our ancient ancestors, began to abate.

[KITTLES:] When we look at the early movement out of Africa, when that constraint was relaxed, we

then see a plethora of variation.

[JABLONSKI (narrated):] In European and Asian populations, geneticists have discovered greater

variation in the MC1R gene, but less variation in several other genes—ones associated with lighter skin

types.

[KITTLES:] Different environments led to other genes being selected for, and being important, for those

populations, in terms of skin color.

[JABLONSKI (narrated):] Selection for light-skin gene variants occurred multiple times in different

groups around the world, some of it in just the last 10,000 years. Support for the idea that the UV-

vitamin D connection helped drive the evolution of paler skin comes from the fact that indigenous

peoples with diets rich in this essential vitamin have dark pigmentation.

[music plays]

[JABLONSKI:] The tension between these two aspects of our biological inheritance—on the one hand,

the need to protect ourselves from most ultraviolet radiation, and on the other, the need to use some

ultraviolet radiation for our own benefit—these forces drove the evolution of the wonderful variation

in human skin color that we see around us today.

[JABLONSKI (narrated):] It’s the legacy of an evolutionary balancing act necessitated by the different

environmental conditions people have faced around the globe. The thing is, where once human

migrations took many generations, we now move about the planet at the speed of sound. That means

increasing numbers of us have pigmentation that’s not a good match with where we live.

[ABDEL-MALEK:] People with fair skin and red hair, your phenotype is telling you, you have a high risk

of skin cancer if you’re out in the sun. If you’re a dark-skinned individual, living for example in

Scandinavia or in Minnesota, you’re not going to have optimal exposure to UV for optimal vitamin D

synthesis and you need to take supplements.

[JABLONSKI:] We now know that we need to make cultural adaptations like these to stay healthy. But

that’s not all we’ve learned.

[JABLONSKI (narrated):] With the knowledge we now have about evolution, we also know that skin

color is a flexible trait that has changed through time, as various groups of people moved to sunny or

less sunny parts of the world. And we know that skin color is inherited independently of other traits,

and is not associated with other aspects of a person’s appearance or behavior. Skin color is a product

of evolution and should never have been judged as something good or bad. We are a very clever and

adaptable species, and we are one under the sun.

[music plays]

Name: ________________________________ Period: _____

Evolution of Human Skin Pigmentation

Examine the maps and infographics. Use these to help you answer the questions.

1. What is melanin?

2. Why are folate and vitamin D important? What do they do for your body and a developing

baby?

3. How would light skin color balance the needs for vitamin D and folate?

4. How would dark skin balance the needs for vitamin D and folate?

5. In what type of environment would you expect to find darker skin? Lighter skin?

Then complete the Evolution Tool.

jmwilson

Text Box

5.1 Skin Pigmentation Questions

Name: _______Key_________________________ Period: _____

Evolution of Human Skin Pigmentation

Examine the maps and infographics. Use these to help you answer the questions.

1. What is melanin?

Melanin is a pigment molecule involved in skin pigmentation as well as hair and eye color.

2. Why are folate and vitamin D important? What do they do for your body and a developing

baby?

Vitamin D is involved in absorption of calcium. People who get too little vitamin D develop

brittle bones, including a disease known as rickets in children.

Folate is a B-vitamin involved in red and white blood cell development. Folate is especially

important for pregnant women. Insufficient folate can result in birth defects of the spine and

brain.

3. How would light skin color balance the needs for vitamin D and folate?

Light skin pigment is better able to absorb UV-B rays, so more vitamin D is produced.

However, light skin pigmentation does not protect folate, which is destroyed by sunlight.

4. How would dark skin balance the needs for vitamin D and folate?

Dark skin pigment blocks UV-B rays, so individuals are less able to produce vitamin D. Darker

pigment protects folate from UV, so less is destroyed.

5. In what type of environment would you expect to find darker skin? Lighter skin?

Darker skin is advantageous in high UV environments. Lighter skin is advantageous is

advantageous in environments with low UV.

Then complete the Evolution Tool.

Name: ________________________________ Period: ____

Evolution Tool: Human Skin Pigmentation


survival and reproduction of individuals in the population?

(selective forces)



Tim

e 1

Tim

e 2

Tim

e 3





population?traits?

Tim

e 1

Tim

e 2

Tim

e 3

Ecology

Variation


ecology:

High UV (sun) environment

Low UV environment

Skin produces vitamin D when exposed to UV (sun)

Folate is destroyed by UV (sun) radiation



Lighter skin pigmentation

Medium skin pigmentation

Darker skin pigmentation




50% lighter skin50% darker skin


Explain the evolution of human skin pigmentation using the Evolution Three Questions:




Name: ________________________________ Period: ____

Evolution Tool: Human Skin Pigmentation


survival and reproduction of individuals in the population?

(selective forces)



Tim

e 1

Tim

e 2

Tim

e 3





population?traits?

Tim

e 1

Tim

e 2

Tim

e 3

Ecology

Variation


ecology:

High UV (sun) environment

Low UV environment













High vitamin D production, high folate destruction by UV

Medium-high vitamin D production, medium folate destruction by UV

Sufficient vitamin D production, low folate destruction by UV

Sufficient vitamin D production, low folate destruction by UV

Limited vitamin D production, low folate destruction by UV

Very low vitamin D production, very low folate destruction by UV





These are estimates. The trend is what matters!

Explain the evolution of human skin pigmentation using the Evolution Three Questions:




Answer should include:

Variation: lighter, medium, and darker skin pigmentation based on a combination of genes working together to produce the skin pigment trait

Ecology: UV is needed to produce vitamin D, but UV destroys folate molecules. Both vitamin D and folate are important, particularly for the development of babies. Having too little vitamin D and folate can result in health problems that impact the survival of offspring.

Interaction: Skin pigmentation influences the production of vitamin D and the destruction of folate. In high UV environments individuals with darker skin pigmentation have better protection from folate destruction and produce sufficient vitamin D because of the high amount of UV. In low UV environments individuals with lighter skin are able to produce sufficient vitamin D and there is limited folate destruction due to the low amounts of UV. Individuals with medium skin pigmentation would have the advantage in environments with medium UV levels.

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6.1 Explaining Other ExamplesHow did dogs evolve?

Goals

After reviewing this PowerPoint, you should be able to:1)Apply the principles of evolution by natural selection to

new scenarios (variation in heritable traits, selective forces that impact survival and reproduction, and changes in populations over time).

2)Identify more and less correct explanations of evolution.3)Explain why explanations are more of less correct using

your knowledge of evolution by natural selection.

Watch this Cosmos video:https://www.youtube.com/watch?v=aQHBmY6LbiA

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A family has been learning about Evolution. They are watching an episode of Cosmos, and find out that modern Gray wolves and dogs diverged from an extinct wolf species some 15,000 to 40,000 years ago.How could you explain how wolves and dogs became different species?

Here’s what each of them thought:Luis: “Wolves and dogs probably lived separately, so they became more different over time.”David: “They probably lived in different places because wolves and dogs behave differently. Wolves avoid humans and dogs love to be around humans.”Elena: “If some wolves were friendly and helpful to humans, the humans might have fed those wolves and taken care of them.”Mom: “Humans might have bred the friendly wolves. Their offspring would have similar traits to the parents.”Dad: “New species evolve all the time. This is just a natural process of speciation.”

Compare your answer with this key

A group of students are discussing their recent field trip to a local farm. They learned that a population of bacteria live in the soil on a farm. The farmer has been using antibiotics to treat the animals, gradually exposing the soil bacteria to them through runoff and animal waste. How do bacteria cope with their changing environment?

Sam: “The bacteria mutate in response to the antibiotic exposure. Through mutation, some individuals develop the ability to survive at higher antibiotic concentrations. These individuals reproduce while the other bacteria die. Because their offspring inherit the ability to survive at higher antibiotic concentrations, the entire population evolves to be more tolerant of antibiotics.”Casey: “Because of genetic variation, there are already individuals in the population of bacteria that can tolerate increased exposure to antibiotics. These individuals survive better than their peers and produce more offspring. Because their offspring inherit the ability to survive at higher antibiotic concentrations, the entire population evolves to be more tolerant of antibiotics.”Rory: “All of the bacteria adjust their cell machinery so that they can survive exposure to antibiotics. When the bacteria reproduce, their offspring inherit this adjustment and the entire population evolves to be more tolerant of antibiotics.”

Compare your answer with this keySam: “The bacteria mutate in response to the antibiotic exposure. Through mutation, some individuals develop the ability to survive at higher antibiotic concentrations. These individuals reproduce while the other bacteria die. Because their offspring inherit the ability to survive at higher antibiotic concentrations, the entire population evolves to be more tolerant of antibiotics.”Sam is incorrect in saying that “bacteria mutate in response to antibiotic exposure.” Mutations are random. It is true that individual bacteria with mutations that help that to survive the antibiotic will survive to reproduce.Casey: “Because of genetic variation, there are already individuals in the population of bacteria that can tolerate increased exposure to antibiotics. These individuals survive better than their peers and produce more offspring. Because their offspring inherit the ability to survive at higher antibiotic concentrations, the entire population evolves to be more tolerant of antibiotics.”Casey is the most correct. Evolution by natural selection acts on existing variation in the population (which was produced by random mutations and in some organisms sexual reproduction).Rory: “All of the bacteria adjust their cell machinery so that they can survive exposure to antibiotics. When the bacteria reproduce, their offspring inherit this adjustment and the entire population evolves to be more tolerant of antibiotics.”Rory is incorrect in saying that “offspring inherit this adjustment.” He is describing acclimation, when an individual adjusts to conditions in the environment. An example of acclimation is tanning when in the sun, but we know that babies don’t inherit a sun tan from their parents. His explanation sounds more like Lamarck than Darwin.

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Check Your Understanding1) Apply the principles of evolution by natural selection to new scenarios (variation in

heritable traits, selective forces that impact survival and reproduction, and changes in populations over time).

2) Identify more and less correct explanations of evolution.

3) Explain why explanations are more of less correct using your knowledge of evolution by natural selection.

What’s Next?

1) If these examples were challenging, review Lesson 3.1 and your explanation from 5.2. Reach out to your teacher for additional assistance and resources.

2) If you are interested in learning more, consider exploring: OPTIONAL Introduction to Geologic Time PowerPointVideo – Stated Clearly: Does The Theory of Evolution really matter?PBS Deep Time InteractiveHHMI Making of Mass Extinctions interactive timelineVideos – PBS Eons

9

jmwilson

Text Box

Video and interactive links: https://www.youtube.com/watch?v=hqepQGOYKZ0&list=PLInNVsmlBUlQT_peuWctrmGMiLngK-6fb&index=5&t=0s https://www.pbs.org/wgbh/evolution/change/deeptime/index.html http://media.hhmi.org/biointeractive/click/extinctions/?_ga=2.249023426.438836521.1553713826-44292177.1553713826 https://www.pbs.org/show/eons/

https://www.theverge.com/2017/7/18/15992572/dog-genetics-archaeology-fossils-evolution-domestication-wolves

Prehistoric fossils suggest modern dogs evolved from a single population of wolves

By Rachel Becker Jul 18, 2017, 4:43pm EDT

This dog cranium was discovered in Germany in 2010, next to Neolithic human remains. The skull is about 4,700 years old. Photo by Amelie Scheu

The dogs of ancient Europe probably looked a lot like the mutts roaming Europe today, new DNA discoveries from dog fossils suggest. In the ongoing debate over how many times dogs were domesticated from wolves, this new study suggests it happened just once.

Dogs are the very first species that humans tamed, but the details surrounding dogs’ origins are a little fuzzy. Now, ancient DNA extracted from two 7,000-year-old and 4,700-year-old dog fossils discovered in Germany offer scientists a glimpse at dog evolution. Modern dogs probably descended from just one population that lived continuously in Europe for millennia, according to the research led by Krishna Veeramah at Stony Brook University.

Our furry friends likely evolved from a population of wolves domesticated sometime between 20,000 and 40,000 years ago. Exactly who domesticated these wolves, when, and how many times, is still a mystery, and scientists don’t agree on the answer. Dogs were probably domesticated by accident, when wolves began trailing ancient hunter-gatherers to snack on their garbage. Docile wolves may have been slipped extra food scraps, the theory goes, so they survived better, and passed on their genes. Eventually, these friendly wolves evolved into dogs. “People want a story that someone picked up a wolf cub and made a dog — but it’s been a much more complex process than that,” Veeramah says…

…Veeramah’s team also extracted DNA from two more dog fossils discovered in Germany over the last 20 years. They re-created a canid family tree by comparing chunks of DNA from these ancient dogs and today’s purebreds, mutts, and wolves. By counting the genetic differences, and estimating how long it would take for those differences to show up, they could roughly date when each of these groups split apart. For wolves and dogs, that was roughly 20,000 to 40,000 years ago. For Eastern and Western dog populations, it was probably between 17,000 and 24,000 years ago…

https://www.theverge.com/2017/7/18/15992572/dog-genetics-archaeology-fossils-evolution-domestication-wolves

https://www.theverge.com/authors/rachel-becker

http://life.bio.sunysb.edu/ee/veeramahlab/

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How does evolution work over large time scales?

Introduction to Geologic Time

The largest defined unit of time is the eon. Eons are divided into eras, which are in turn divided into periods, epochs and ages. How do scientists figure out

what happened on Earth billions of years ago?

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6.1 OPTIONAL Introduction to Geologic Time

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Fossils form under certain conditions

Relative dating• Determining the sequence of past events• Uses geology and order of rock layers

Absolute (radiometric) dating• Some isotopes of elements are not stable• Radioactive isotopes “decay” to form stable

isotopes• Scientists can measure the amount of

radioactive isotopes in a sample to determine the absolute age of that sample

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Optional video:PBS Eons “A Brief History of Geologic

Time” (12:07)


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https://www.youtube.com/watch?v=rWp5ZpJAIAE

Name: ______________________________________________________ Period: ___________

Evolution Self-Assessment

Reflect on the standards addressed in the Evolution unit. Check which box describes your current

understanding: 4 I know this well enough to teach it to someone.

3 I can do this with almost no mistakes.

2 I can do much of this, but I have questions.

1 I can do this, but only with help.

0 I can’t do this, even with help.

Notes / Comments:

Evolution Standards Rating

(0-4)

I can describe the variety of traits in a population using numbers and probabilities.

I can evaluate evidence showing how group behavior increases an individual’s and a species’ chances

to survive and reproduce.

I can describe how common ancestry and biological evolution are supported by multiple types of

scientific evidence.

I can explain how the process of evolution primarily results from four factors: (1) the potential for a

species to increase in number, (2) the heritable genetic variation of individuals in a species due to

mutation and sexual reproduction, (3) competition for limited resources, and (4) the increase of those

organisms that are better able to survive and reproduce in the environment.

I can use numbers to explain that organisms with an advantageous heritable trait tend to increase in

proportion to organisms lacking this trait.

I can explain how natural selection leads to adaptation of populations.

I can explain how changes in environmental conditions may result in (1) increases in the number of

individuals of some species, (2) the emergence of new species over time, and (3) the extinction of

other species.

Name: _____________________________________________ Class: __________________________

KEY Learning Tracking Tool for Evolution: How does the environment impact species over time? How will species change or adapt?

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What did we do? What did we figure out?

Summarize key information and activities with a description and/or

picture.

How can our learning be used to explain the phenomenon?

Describe what you will you add to your explanation of the phenomenon.

Self-Assess:

Where am I with my understanding of the

phenomenon?

(Example: Ready to explain, starting to get it, need more information)

What questions do I have?

What additional information do you need

to understand the phenomenon?

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Evolution is the change in the heritable traits of a population over time. Evolution is a scientific theory, which is an explanation for what we see in the natural world that can be tested and verified. Evidence for evolution includes comparative anatomy, embryology, fossils, DNA, and the geographic distribution of species.

There is a connection between malaria and Sickle Cell Disease. Having one S allele gives resistance to malaria.

Students MIGHT say:

Species evolve to survive in their environment.

In environments where malaria is present, having the sickle cell allele S is an advantage.

Many options!

Example:

How do species evolve?

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We examined data that shows that in environments with malaria the frequency of the S allele is higher than in environments without malaria. This makes sense because having the genotype AS makes a person resistant to malaria, so there is an advantage to having the S allele.

Students MIGHT say:

Malaria in the environment impacts the evolution of the A and S alleles in human populations.

Many options!

Example:

What is natural selection?

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Evolution acts on variation in heritable traits in the population. Individuals compete for resources and only some survive to reproduce. This interaction between variation and the environment results in changes in the population over time (evolution).

Charles Darwin’s theory of evolution by natural selection matches our findings. Lamarck incorrectly thought that individuals would pass on acquired traits to their offspring.

Students MIGHT say:

Individuals don’t evolve, populations evolve. Evolution by natural selection works on variation in the heritable traits of a population based on which traits help individuals to outcompete others and to survive and reproduce.

Many options!

Example:

How did humans evolve?

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Humans (Homo sapiens) are primates. Our closest living relative is the chimpanzee. All other hominins (human-like primates) have gone extinct, including the other species in our genus Homo. Hominins are unique because of the evolution of bipedalism, walking on two legs. This required changes in our anatomy, including the spine and hips. Humans have large brained which have enabled us to be flexible and to survive changes in climate.

Students MIGHT say:

Humans have different adaptations from other primates including walking on two legs and large brains. These adaptations enabled us to access different resources and to spread across the world.

Many options!

Example:

How can we explain variations in the

human population?

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tion There are patterns of lighter and

darker skin pigmentation across the globe. These patterns coincide with the amount of UV radiation in those regions, with lighter skin pigmentation in areas with low UV and darker in areas with high UV. This occurs because UV radiation is needed to produce vitamin D, but UV destroys folate.

Students MIGHT say:

Human skin pigmentation varies based on UV conditions in the environment. In places with high UV, darker skin pigmentation balances the need for vitamin D with protection from folate destruction. In places with low UV, lighter skin pigmentation allows for vitamin D production and folate destruction is low.

Many options!

Example:

How did other species evolve?

science learning packet bio b evolution packet

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