Charles Darwin (1809-1882) Charles Darwin (1809-1882) Sailed around the world 1831-1836Sailed around the world 1831-1836

2. What did 2. What did Darwin’s Darwin’s Travels revealTravels reveal

The diversity of living The diversity of living species was far greater species was far greater than anyone had than anyone had previously known!!previously known!!

These observations led These observations led him to develop the him to develop the theory of evolution!!theory of evolution!!

3.How did tortoises and 3.How did tortoises and birds differ among the birds differ among the islands of the Galapagos?islands of the Galapagos?

Each island Each island had its own had its own type of type of tortoises tortoises and birds and birds that were that were clearly clearly different different from other from other islandsislands

Galapagos Galapagos TurtlesTurtles

4. Evolution is when organisms change 4. Evolution is when organisms change over time. So, modern organisms over time. So, modern organisms descended from ancient onesdescended from ancient ones

7. Evolution is a Theory – 7. Evolution is a Theory – Just like Gravity!Just like Gravity!

• Evolution is a well Evolution is a well supported explanation supported explanation of phenomena that of phenomena that have occurred in the have occurred in the natural worldnatural world

• A theory in science is A theory in science is a well tested a well tested hypothesis, not just a hypothesis, not just a guessguess

5. 5. Geologists: Geologists: Hutton and LyellHutton and Lyell

Fundamentalists said that the Fundamentalists said that the earth was around 6000 years oldearth was around 6000 years old

Hutton and Lyell argued that the Hutton and Lyell argued that the earth is many millions of years earth is many millions of years old b/cold b/c

layers of rock take time to formlayers of rock take time to form processes such as volcanoes processes such as volcanoes

and earthquakes shaped the and earthquakes shaped the earth and still occur todayearth and still occur today

6. Lamark6. LamarkTheory of acquired Theory of acquired characteristicscharacteristics

Lamark said Lamark said organisms acquired organisms acquired traits by using their traits by using their bodies in new waysbodies in new ways

These new These new characteristics were characteristics were passed to offspringpassed to offspring

Lamark was totally Lamark was totally wrong!wrong!

7. Malthus7. Malthus

Reasoned that if the Reasoned that if the human population human population continued to grow continued to grow unchecked, sooner or unchecked, sooner or later there would be later there would be insufficient living space insufficient living space and food for everyone and food for everyone

8. Darwin 8. Darwin finally finally published his published his ideas in 1859ideas in 1859 Other naturalists Other naturalists

were developing were developing the same theory the same theory that Darwin did. that Darwin did.

Even though he Even though he was afraid of the was afraid of the Church’s reaction Church’s reaction to his book he to his book he wanted to get wanted to get credit for his credit for his work.work.

9. Artificial Selection 9. Artificial Selection nature provides variation, humans select nature provides variation, humans select

variations that are useful. variations that are useful. Example - a farmer breeds only his best Example - a farmer breeds only his best

livestocklivestock

10. Natural 10. Natural SelectionSelection The traits that The traits that

help an organism help an organism survive in a survive in a particular particular environment are environment are “selected” in “selected” in natural selectionnatural selection

11. Natural Selection and 11. Natural Selection and Species FitnessSpecies Fitness

Overtime, natural selection results in Overtime, natural selection results in changes in the inherited changes in the inherited characteristics of a population. characteristics of a population.

These changes increase a species These changes increase a species fitness (survival rate)fitness (survival rate)

Descent with Descent with Modification Modification Each living Each living

species has species has descended descended with changes with changes from other from other species over species over timetime

Summary of Darwin’s TheorySummary of Darwin’s Theory

1. Organisms differ; variation is inherited1. Organisms differ; variation is inherited

2. Organisms produce more offspring than 2. Organisms produce more offspring than survivesurvive

3. Organisms compete for resources3. Organisms compete for resources

4. Organisms with advantages survive to pass 4. Organisms with advantages survive to pass those advantages to their childrenthose advantages to their children

5. Species alive today are descended with 5. Species alive today are descended with modifications from common ancestorsmodifications from common ancestors

13. Evidence of Evolution13. Evidence of Evolution

1.1. Fossil RecordFossil Record

2.2. Geographic Distribution of Living Geographic Distribution of Living SpeciesSpecies

3.3. Homologous Body structuresHomologous Body structures

4.4. Similarities in Embryology Similarities in Embryology

Evidence of Evidence of EvolutionEvolution

Fossil Record provides evidence Fossil Record provides evidence that living things have evolvedthat living things have evolved

Fossils show the history of life on Fossils show the history of life on earth and how different earth and how different groups of organisms have groups of organisms have changed over timechanged over time

Relative Relative vs. vs. Absolute Absolute DatingDating

Relative Relative DatingDating

Can determine a Can determine a fossil’s relative agefossil’s relative age

Performed by Performed by estimating fossil age estimating fossil age compared with that of compared with that of other fossilsother fossils

Drawbacks – provides Drawbacks – provides no info about age in no info about age in yearsyears

Absolute Absolute datingdating

Can determine the Can determine the absolute age in absolute age in numbersnumbers

Is performed by Is performed by radioactive dating – radioactive dating – based on the amount of based on the amount of remaining radioactive remaining radioactive isotopes remainisotopes remain

Drawbacks - part of the Drawbacks - part of the fossil is destroyed fossil is destroyed during the testduring the test

Carbon-14 DatingCarbon-14 Dating

Fossil Formation SGFossil Formation SG

Primate FossilsPrimate Fossils

Australopithecus Homo erectus Homo sapien

Primate Primate Brain Brain CapacityCapacity

Primate Bone structurePrimate Bone structure

Human RelativesHuman Relatives

AustralopithecusAustralopithecusafarensisafarensis

Homo habilis = handy humanHomo habilis = handy human1.5 to 2 mya1.5 to 2 mya

Homo erectusHomo erectus1.6 mya1.6 mya

bipedal

Neanderthals35,000 to 100,000 ya

Cro-Magnon35,000 to 40,000 ya

Modern Homo sapien(fully modern fossils 100,000 ya)

13. Evidence of 13. Evidence of EvolutionEvolution

2.2. Geographic Geographic Distribution of Living Distribution of Living SpeciesSpecies

Similar animals in Similar animals in different locations different locations were the product of were the product of different lines of different lines of descentdescent

13. Evidence 13. Evidence of of EvolutionEvolution

Homologous Body Homologous Body StructuresStructures

Structures that have Structures that have different mature different mature forms but develop forms but develop from the same from the same embryonic tissuesembryonic tissues

e.g. Wing of bat, e.g. Wing of bat, human arm, leg of human arm, leg of turtleturtle

Turtle

Alligator

Bird

Homologous Body Homologous Body StructuresStructures

Vestigial OrgansVestigial Organs

traces of homologous organs in other traces of homologous organs in other speciesspecies

Organ that serves no useful functionOrgan that serves no useful functione.g. Appendixe.g. Appendix

13. Evidence of 13. Evidence of EvolutionEvolution

Similarities in Similarities in EmbryologyEmbryology

In their early In their early stages of stages of development, development, chickens, turtles chickens, turtles and rats look and rats look similar, providing similar, providing evidence that evidence that they shared a they shared a common common ancestry.ancestry.

Embryological developmentEmbryological development