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Human Origins and Evolution

Human Origins and Evolution. Homo sapiens: “ The wise human ”. Probably first appeared about 200,000 years ago . Paleoanthropologists study human evolution .

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Human Origins and Evolution

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  1. Human Origins and Evolution

  2. Homo sapiens: “The wise human” • Probably first appeared about 200,000 years ago. • Paleoanthropologists study human evolution. • There is sparse evidence relating to the evolution of humans - pieces of a puzzle in time, some out of sequence, with many pieces missing. • DNA, RNA, proteins, and chromosomes are filling in the gaps in our knowledge of the past. • Species with common DNA sequences are more likely to have arisen from a common ancestor. • Humans belong to the order of mammals called primates. Other primates include tree shrews, lemurs, tarsiers, monkeys, and apes.

  3. Characteristics of Primates • Traits of primates: • mostly arboreal (live in the trees) • highly movable fingers and toes • flattened nails • good vision • color vision (to locate ripe fruit) • front-facing eyes & depth perception • reduced snout, decreased sense of smell. • ability to hold body in vertical position

  4. Types of Primates Anthropoids • Monkeys, apes, and humans • Well developed collar bone, rotating shoulder joints, partially rotating elbow joints (strength and flexibility) • Opposable thumb – a thumb that can be positioned opposite the other fingers – precision grip • Most also have opposable big toe. • Large brain for body size.

  5. Cont’d • Fossils show brains get bigger over time. Look at cranial capacity (size of brain case). • Humans and apes- gibbons, orangutans, gorillas, and chimpanzees – have a large cranial capacity relative to body size. • Humans and apes have become increasingly capable of sitting, standing, or walking erectly. • Tail bones reduced in apes and humans.

  6. Characteristics of Humans • Bipedal – upright walking on two legs. • Pelvic bones – broad with muscular attachments (supports internal organs during walking) • Foot – big toe aligned with other toes – distributes weight evenly • Jaw and teeth – U-shaped jaw with wide spaces between teeth in apes (pull branches through teeth to strip off leaves). Round jaw with smaller and less specialized teeth (more varied diet) • Brain - Cranial capacity (1,400 cm3) larger than other primates. Large forehead (large frontal part of the brain – verbal language.

  7. Aegyptopithecus • 30 - 40 million years ago • cat sized • could run on the ground • lived in the trees • social • males had large canine teeth

  8. Hominoids • 22-32mya • ancestors of apes and humans • lived in trees, but walked more than aegytopithecus • many different forms

  9. Hominids • 4 – 19 mya • ancestors of humans only

  10. Australopithecines • 4 mya • bipedal • hunter-gatherer lifestyle • flat skull bases • humanlike teeth • gorilla-sized brains • 4-5 feet tall • did not live in the forest

  11. A. afarensis • 3.6 mya • “Lucy” (1974, Ethiopia) • less than 1.5 m tall. • 380 – 450 cm3 cranial capacity (1/3 modern)

  12. A. africanus • 2.8 mya • taller and heavier than A. afarensis • 430 – 550 cm3

  13. A. rubustus & A. boisei • 1-2 million years old (Africa) • heavier skulls and larger back teeth • 450 – 600 cm3

  14. A. garhi • 2.5 mya • Possibly the “missing link” (bridge between Australopithecus and Homo) • Ethiopia near younger Homo fossils • Hunted (butchered antelope)

  15. Homo • 2.3 mya - present • Early species coexisted with Autralopithecus

  16. H. habilis • 1.6 – 2 mya • “handy human” • used tools, butchered animals • 600 – 800 cm3

  17. H. erectus • .5 – 1.6 mya • “upright human” • Fossils found in Java (south pacific island) • Thick skull, large brow ridges, a low forehead, & a very small chin • 700 – 1,250 cm3 • Probably as tall as modern humans • Used stone tools and hunted • Built fires • Signs of social organization • Angled skull that permitted them to make a greater range of sounds. • Widespread (China, Africa, and Asia) • Families of male-female pairs • Male hunted and female nurtured young • Some fossils as recent as 35,000 ya

  18. H. sapiens - (“the wise human”) probably appeared ~200,000 ya.) • Neanderthal • 150,000 – 28,000 ya • slightly larger brains than humans • prominent brow ridges • gaps between certain teeth • muscular jaws with small chin • large barrel-shaped chests. • 5 ft tall • adapted to cold climate of northern Europe • lived in caves and stone shelters • lived at same time as modern humans

  19. H. Sapiens – Cont’d • Cro-magnon (modern) • 35,000 ya • 1,400 cm3 • high forehead, prominent chin, lack of brow ridges • taller than Neanderthals • sophisticated culture

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