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Primate Evolution.ppt
- 1. Primate Evolution KEY CONCEPT Humans appeared late in Earth’s history.
- 2. Primate Evolution Humans share a common ancestor with other primates. • Primates are mammals with flexible hands and feet, forward-looking eyes and enlarged brains.
- 3. Primate Evolution Primate characteristics • Rounded heads • Flattened faces • Opposable thumb • Binocular vision • Flexible joints • Full arm motion • Some with prehensile tails • Large brains
- 4. Primate Evolution Groups of primates ancestral primates lemurs and ayes-ayes Tarsiers and anthropoids Lemur Tarsier
- 5. Primate Evolution • Primates evolved into prosimians and anthropoids. – Prosimians are the oldest living primates. – They are mostly small and nocturnal.
- 6. Primate Evolution – They are subdivided into the New World monkeys, Old World monkeys, and hominoids. – Anthropoids are humanlike primates. – Homonoids are divided into hominids, great apes, and lesser apes. – Hominids include living and extinct humans.
- 7. Primate Evolution New World monkeys • Habitat: rainforests of Central and South America • Prehensile tail: able to grasp and hold with this fifth limb Squirrel monkey
- 8. Primate Evolution Old World monkeys • Larger than New World monkeys • Tails that are not prehensile • Appear superficially to be like hominoid apes except that apes lack tails. • Habitat: diverse, including African savanna and Japanese mountains Mandril
- 9. Primate Evolution Hominoid apes: orangutans, gibbons, chimpanzees, bonobos, and gorillas • long, muscled forelimbs – climbing in trees – swinging from branches – knuckle walking Bonobo knuckle-walking
- 10. Primate Evolution Comparing DNA of humans and chimps • Humans and chimps share the greatest sequence of DNA nucleotides. • This implies that humans and chimps are more likely to share a recent ancestor. • This does not imply that humans descended from chimps.
- 11. Primate Evolution Human evolution • Fossil and DNA evidence indicates that about 5 to 8 million years ago, an ancestral hominoid diverged into two pathways: chimps and humans. • Changes in food supply and climate favored those hominoids that could forage for food on land rather than in trees.
- 12. Primate Evolution Characteristics for non- arboreal primates • Bipedal: using two legs for upright walking • Upright posture: facilitates primate to see farther • Bipedal hominoid primates are called hominids and include humans. Bipedalism is a more adapted behavior than knuckle-walking apes.
- 13. Primate Evolution How do scientists know that early hominids walked upright? • The opening in the skull where the spinal cord attaches shows how the head and spine are positioned. • Anthropologist Raymond Dart discovered an early skull that appeared ape-like but had the spinal attachment position like modern humans. Notice how the angle of the arrow changes with the human skull as compared to the ape and chimp.
- 14. Primate Evolution • Bipedal means walking on two legs. – foraging – carrying infants and food – using tools • Walking upright has important adaptive advantages.
- 15. Primate Evolution There are many fossils of extinct hominids. • Most hominids are either the genus Australopithecus or Homo. • Australopithecines were a successful genus. • The Homo genus first evolved 2.4 million years ago.
- 16. Primate Evolution Where did hominoids come from? • Scientists believed that Old World and New World monkey shared a common anthropoid ancestor. • From DNA evidence, scientists believe this to be the order of ape evolution: gibbons, orangutans, African apes, gorillas, and chimpanzees.
- 18. Primate Evolution Modern humans arose about 200,000 years ago. • Homo sapiens fossils date to 200,000 years ago. • Human evolution is influenced by a tool-based culture. • There is a trend toward increased brain size in hominids. Australopithecus afarensis Homo habilis Homo neanderthalensis Homo sapiens
- 20. Primate Evolution Raymond Dart with Taung skull • Taung child, which was discovered in 1924 in South Africa. • Taung child was originally thought to be a fossil of a child because of its small size. • An endocast of the brain revealed fissures that were more human-like than ape- like. • Australopithecus africanus or “southern ape from Africa”
- 21. Primate Evolution Australopithecus africanus • The skull that Dart discovered was named A. africanus. • Estimated age: 2.5 to 2.8 MYO • These primates are called australopithecines (apelike and humanlike).
- 22. Primate Evolution 1974 discovered australopithecine Lucy Australopithecus afarensis, dated about 2-3 MYO, shows pelvis structures that would indicate bipedalism.
- 23. Primate Evolution Comparing skulls and pelvic bones Chimps Early hominid Modern human Similar brain case size between these two Shorter and wider pelvic bones indicate bipedalis
- 24. Primate Evolution Australopithecine extinction • Fossil records indicate a disappearance about 2.0-2.5 MYA. • Hominids more like modern humans with larger brain cases may have evolved next. In 1964, Louis and Mary Leakey discovered skulls more like modern humans in Tanzania and named this group Homo.
- 25. Primate Evolution Homo habilis • “handy man” • Ancient stone tools found near the fossils of H. habilis • Estimated age: 1.5-2.5 MYO Examples of tools that H. habilis may have used
- 26. Primate Evolution Homo erectus may have evolved from H. habilis.
- 27. Primate Evolution H. erectus characteristics • Larger brain than H. habilis • More human-like face
- 28. Primate Evolution H. erectus • Stone hand axe were found near H. erectus fossils, indicating they hunted. • Hearths with charred bones found in H. erectus caves indicate that they may have used fire.
- 29. Primate Evolution H. erectus migration • About 1 MYA, H. erectus migrated throughout Africa, Asia, and Europe. • They became extinct between 130,000 and 300,000 years ago. • This is about the time that Homo sapiens fossils appear in the fossil record (100,000-500,000 YA).
- 30. Primate Evolution Neanderthals – Homo group • 35,000-100,000 YA in Europe, Asia, and Middle East • Larger brain cases than H. erectus • Prominent nose • Thick bones • May be a sister species to modern humans (not direct ancestor) • Lived about the same time as Cro-Magnon
- 31. Primate Evolution Cro-Magnon – early humans • 35,000-40,000 YA • Same height, skull structure, tooth structure, and brain size as modern humans • Toolmakers and artists • Language
- 32. Primate Evolution Possible appearance of Cro- Magnon
- 33. Primate Evolution Early humans crossing land bridge • 12,000 years ago, evidence shows that they crossed a land bridge into North America. • They built settlements and domesticated animals. Modern coastline Ancient coastline Ice sheets 21,000 yrs ago Ice sheets 12,000 yrs ago Possible migration route
- 34. Primate Evolution Robert Broom: One of Dart’s Few Supporters • In 1934, at the age of of 68, Broom gave up his medical practice to take a position at the Transvaal Museum in Pretoria. • In 1936, he decided to search for more of Dart's australopithecines. • Broom recognized two types of australopithecines: gracile and the robust. • In 1948 he started excavating at Swartkrans, which yielded remains of what was later determined to be Homo erectus, as well as further australopithecine fossils.
- 37. 13.1 Ecologists Study Relationships
- 39. Primate Evolution Internet Sources • http://salamander.uky.edu/srvoss/schedule06.htm • http://www.becominghuman.org/ • TREE OF LIFE PROJECT: http://tolweb.org/ • http://en.wikipedia.org/wiki/Theria • http://en.wikipedia.org/wiki/Australopithecus • http://jp.reuters.com/news/articlenews.aspx?type=scienc eNews&storyID=2007-04- 20T202309Z_01_N20329580_RTRUKOC_0_US- CHIMPANZEES-GENES.xml&WTmodLoc=Home-C5- scienceNews-3