HUMAN EVOLUTIONCHAPTER 26 SECTION 4

SC.912.L.15.1…HIGH (explain how the theory of evolution is supported by the fossil record,

comparative anatomy, biogeography, molecular biology, and observed evolutionary change)

SC.912.L.15.10…MEDIUM ( identify basic trends in hominid evolution from early ancestors six million years ago to modern humans, including brain size,

jaw size, language, and manufactured tools.)

• A. PRIMATE EVOLUTION. 233 species of mammals called primates (order primates). Lemurs, monkeys, apes, humans. Hypothesis supports that human evolved from a tree dwelling, insect eating ancestor app. 65mya.

1. CHARACTERISTICS. Now live on the ground, and retain adapt. For living on trees. EX: a) Flexible shoulders for swinging.b) Sensitive fingers instead of claws.c) Hands can hang and manipulate food.d) Binocular vision. Eyes in front of the face and the

field of vision overlap enhancing depth perception.

2. -2 MAJOR GROUPS. First group includes lorises, galagos, and lemurs. Lemurs live in Madagascar, and lorises live in Africa and South Asia. They are mostly nocturnal, tree dwellers and have claws. Second Group includes tarsiers, new world monkeys, old world monkeys, apes and humans. 1. tarsiers…live in s. east asia2. N.W.Monkeys..live in the Americas, tree dwellers,

have prehensile (grasping) tails for swinging.3. O.W. Monkeys….tree dwellers but tails are not

prehensile.include baboons, macaques, and mandrills

• 4. APES…gibbons, orangutans, gorillas,and chimpanzees. Larger than other primates, long arms, short legs, no tails. They can swing. Gorillas and chimps are highly social of all. Chimps are the closest relatives from humans differing in less than 2% of their DNA sequence.

• ONLINE ACTIVITY 26-4

• B. HOMINID EVOLUTION Members of the human family are called hominids (Family Hominidae, Order Primates). Only 1 species of hominids exist : Homo sapiens (modern man). Earliest man may have lived 6 to 7mya. 2 important developments:

• 1. WALKING UPRIGHT. …Australepithecus aferensis is the oldest evidence of upright posture and walking on 2 feet……BIPEDALISM (4mya). Became extinct 1.4mya…famous LUCY. Walking upright developed bef. Big brain.

• 2. ENLARGED BRAINS. First appeared in East Asia 2.5mya. Large brains found with tools…Homo habilis. Homo erectus ..taller than habilis, had a larger brain…app.1200cc.

Increase in intelligence gave them success in Africa.

• C. HYPOTHESES FOR THE ORIGIN OF FULLY MODERN MAN.

• 1. MULTIREGIONAL HYPOTHESIS. Fully modern human developed from H.erectus descendents that spread from Africa 1.5 mya. Interbreeding among regional H.sapiens evolved as a single species.

• 2. REPLACEMENT HYPOTHESIS. Says that all regional H.erectus became extinct all over the world and that humans descended from a group of H. erectus that remained in Africa. They started spreading out 100,000 ya replacing the other.

• - DNA supports a very recent split from a common ancestor.

• DRAW FIGURES 26-22 AND 26-23 CHAPTER (26-4)

ORIGINS OF LIFESC.912.L14.5 Theory of the origins

of life…Highsc.912.l.14.5 explanations of the

origins. ..moderate(note: everytime you encounter a

figure you must draw it in your interactive notebook)

SECTIONS 16-1 AND 17-5

• A. OLDEST FOSSILS• 1. STROMATOLITES. Oldest fossils about 3.5

million years old, found in domes called stromatolites. Made of layers of prokaryotic photosynthetic bacteria also called CYANOBACTERIA or BLUE-GREEN ALGAE.

• It contain chlorophyll which permits it perform photosynthesis.

• Page 356

• 2. FORMATION OF ORGANIC POLYMERS. Miller’s exp. Provided evidence that small organic molecules could have formed from physical and chemical processes. How did polymers (long chains of molecular units [monomers]) formed without living cells or enzymes being present? Polymers= polypeptides(amino acids) and polysaccharides (sugars). DRAW FIGURE 16-2, page 357

• Experiments: solution of amino acids dropped onto the surface of hot sand, water evaporates and leaves behind the amino acids then bond together to form polypeptides. Also, CLAY, concentrate amino acids and other monomers held together.

• 3.THE RNA WORLD. One important characteristic of life is inheritance which is based on molecules that can copy themselves. Cells today TRANSCRIBE genetic information from DNA to RNA which then directs the synthesis of enzymes and other proteins.

• One hypothesis of ancient cells is that the first genes were short strands of RNA that could replicate without the help of enzymes or other cells. RNA has shown to make a copy of themselves in solution containing nucleotides (thymine, adenine, cytosine, guanine). FIGURE 16-3. PAGE 358.

• Basically an RNA world= included stored genetic information and directed protein synthesis.

• 4.FORMATION OF PRE-CELLS. Biologist hypothesize that early organic molecules became organized into increased level of order by becoming encased in a membrane. Experiments show that polypeptides can form fluid filled spheres. If lipids are included in the solution they form selectively permeable membranes. These are called Pre-cells. They are NOT living but show properties of living cells. FIG. 16-4.page 358

• SUMMARY• FIRST. small organic molecules such as nucleotides and

amino acids formed from small organic molecules.• SECOND. Small molecules joined together to form

proteins and nucleic acids. ONLINE ACTIVITY. 16-1

• THIRD. Molecules that can copy themselves provide a basis for inheritance.

• FOURTH. These molecules became packaged with membranes and separated from their surroundings to form pre-cells.

• ------------------------------------------------------------These exp. Do not say that life originated for sure this way. They simply show that life COULD have arisen this way. There is a lot of debate going on which is part of scientific work.

B. ORIGINS OF LIFE.WHERE DID LIFE BEGIN?? WHAT CONDITIONS ALLOWED LIFE ON EARTH??

• Until recent researchers thought that life had originated in shallow water or moist sediments as clay.

• But, the early earth was hot and after the discovery of deep see hydrothermal vents raised the possibility that similar environments may have supplied the energy and the chemical raw materials for the origin of life.

• Ex: Deep sea vents are populated with prokaryotic organisms.

C. THEORIES OF THE ORIGIN OF LIFE.

• 1. ABIOGENESIS (SPONTANEOUS GENERATION)

• Until the mid of the 19th century it was thought that organisms arose from mud or organic matter.

• They thought that maggots arose from meat and mice from rice..(spontaneous generation)

• In 1968, an Italian Physician Francesco Redi disproved the believe of SPONTANEOUS GENERATION at that time with his experiment.

• He performed a controlled experiment:• DRAW REDI’S EXPERIMENT.(leave space)• He convinced many scientists that maggots did not arise

from spontaneous generation, but not totally. They still thought that microorganisms arose from the air.

• Disproving this was difficult. Finally in the mid 1800s, LOUIS PASTEUR designed an experiment that disproved spontaneous generation of microorganisms.

• DRAW PASTEUR’S EXPERIMENT.(leave space )• Pasteur set up an experiment in which air but no

microorganisms was allowed to contact a broth that contained nutrients.

• Pasteur’s experiment showed that microorganisms do not simply arise in broth, even tin the presence of air. From time on, BIOGENESIS, the idea that living organisms come only from other organisms, became a cornerstone of biology.

• 2. ENDOSYMBIOTIC THEORY. (the origin of eukaryotes).

• A widely accepted theory is a combination of 2 processes.

• 1. In the first (INFOLDING) one internal membranes such as endoplasmic reticulum, golgi apparatus, and the nuclear envelope evolved from the inward fold of the plasma membrane of ancestral prokaryotic cells.

DRAW FIGURE 17-18 PAGE 395. INFOLDING ONLY!! These membranes allows the cell to carry out more complex chemical reactions in separate compartments.ONLINE ACTIVITY 17-5

• 2. The second on (ENDOSYSMBIOSIS) led to the existence of mitochondria and chloroplast. Scientist hypothesize that small symbiotic prokaryotes lived within other larger host prokaryotes.

• DRAW FIGURE 17-18.PAGE 395 ENDOSYSMBIOSIS ONLY!!

• Apparently the symbiotic ancestors of mitochondria were aerobic (use oxygen in cellular respiration).

• Similarly, the ancestors of chloroplast could have been photosynthetic bacteria that lived inside a larger host cell. Since all cells have mitochondria and only some have chlorophyll, mitochondria may have evolved first.

EVIDENCE FOR ENDOSYSBIOSIS

• Present day mitochondria and chlorophyll are similar to prokaryotic cells in at least 2 ways:

• 1). They both contain DNA , RNA and ribosomes.• 2). They both copy their own DNA and reproduce

within the host cell by a process resembling the binary fission of prokaryotes.

FIRST ORGANIC MOLECULES• CYANOBACTERIA AND THE OXYGEN REVOLUTION.• Earth’s early atmosphere was anaerobic (little or no

oxygen). As cyanobacteria evolved created oxygen as a by product and bubbled to the surface of lakes and oceans and entered the atmosphere.

• At first, it was toxic for most organisms and caused extinctions. Except for the ones that could hide deep in the mud like some do today.

• Others adapted and extracted oxygen from food through cellular respiration (aerobic organisms)

• Today atmospheric oxygen is recycled by photosynthesis is cyanobacteria, algae, and plants.

• Today many prokaryotes and nearly all eukaryotes are aerobic.

• The “oxygen revolution” was a major episode in the history of life.

• Online activity 16-2