Anatomy & Physiology Unit 6: Human Evolution

1. Anatomy & Physiology Unit 6:Human Evolution

2. Kingdom Animal Phylum Chordate Class Mammal Order Primates Family Hominids Genus Homo Species Sapiens Classification Hierarchy

3. Evolution of Primates • The evolution of primates is characterized by trends towards: • mobile limbs • grasping hands (with opposable thumbs) • a flattened face • binocular vision • a large, complex brain (for learned behavior) • a reduced reproductive rate

4. Mobile Limbs • Most primates have flat nails as well as sensitive pads on the undersides of fingers and toes. • Many also have both an opposable big toe and thumb. • Mobile limbs and clawless opposable digits allow primates to freely grasp and release tree limbs.

5. Primate Hands

6. Binocular Vision • Stereoscopic vision and resultant depth perception allows primates to make accurate judgments about distance and position of adjoining tree limbs.

7. Evolution of Primates • Prosimians were the first type of primate to diverge from the ancestral primate line. • Surviving anthropoids are classified into three superfamilies. • New World monkeys • Old World monkeys • Hominoids

8. Hominoid Evolution • Proconsul is believed ancestral to hominids.

10. Evolution of Hominids • Phylogenetic tree indicates humans are most closely related to African apes. • Last common ancestor appears to have lived about 5-7 million years ago (mya) • Genetic changes used as a molecular clock to measure relatedness of different groups.

11. Hominids • To be a hominid, a fossil must have an anatomy suitable for standing erect and walking on two feet. • Bipedalism • Human anatomy differs from that of an ape largely because humans are bipedal while apes are quadrupedal.

12. Australopithecines • It is possible that one of the australopithecines that evolved and diversified in Africa 4 mya is a direct ancestor of humans. • Southern Africa • Australopithecus africanus • Eastern Africa • Australopithecus afarensis (Lucy)

13. Lucy • A reconstruction of Lucy’s skeleton • Lucy is ~ 3.5-million-years-old • Australopithecusafarensis • adaptations in Lucy’s hip, leg and foot allowed a fully bipedal means of locomotion

14. Hominid Footprints • Preserved in volcanic ash in Tanzania • Discovered in 1978 • Proved hominids were bipedal walkers at least 3.5 million years ago • Most scientists think the footprints were made by A. afarensis, whose fossils are found nearby

15. Landscape with A. afarensis Re-creation of a Pliocene landscape showing members of A. Afarensis gathering and eating various fruits and seeds

16. Evolution of Early Homo • Homo habilis, dated between 2.0 an 1.9 mya, may be ancestral to modern humans. • Skulls suggest portions of the brain associated with speech were enlarged. • Ability to speak may have led to hunting cooperatively and the advent of culture.

17. Human Evolution

18. Skull of Homo erectus • A reconstruction of the skull of Homo erectus • a widely distributed species • whose remains have been found in Africa, Europe, India, China, and Indonesia

19. Homo erectus • Homo erectus and like fossils are found in Africa, Asia, and Europe and are dated between 1.9 and 0.3 mya. • Larger brain and flatter face than Homo habilis. • Much taller than previous hominids. • Believed to have first appeared in Africa and then migrated into Asia and Europe. • First hominid to use fire.

20. Homo erectus Using Tools • Re-creation of a Pleistocene setting in which Homo erectus use fire & stone tools

21. Evolution of Modern Humans • Most researchers believe Homo sapiens evolved from Homo erectus. • Multiregional Continuity Hypothesis • Similar evolution occurred in many different places. • Out-of-Africa Hypothesis • H. sapiens evolved from H. erectus only in Africa, and thereafter migrated to Europe.

22. Evolution of Modern Humans

23. Neanderthals • Neanderthal (H. neanderthalensis) skeletons were first discovered in Germany’s Neander Valley. • Skeletons date back 200,000 years. • Massive brow ridges with protruding nose, jaws, and teeth. • Heavily muscled. • Culturally advanced. • Manufactured variety of tools.

24. Reconstructed Neanderthal skull • characterized by prominent heavy brow ridges and week chin

25. Burial Ceremony in a Cave Neanderthals lived in caves and had ritual burials, such as this depiction from Shanidar Cave, Iraq

26. Neanderthals (190,000 – 27,000 yrs ago) Flaked stones that fit in wood handles. Buried their dead with spices and bedding. Built sturdy huts. Made flutes! A flute formed from a femur & 4 remaining holes.

27. Cro-Magnons – Homo sapiens • Oldest fossils to be designated H. sapiens. • Modern humans who entered Asia and Europe from Africa 100,000 years ago. • Made advanced stone tools. • Accomplished hunters. • Hunted cooperatively. • First to have complex language?

28. Painting From a Cave in France • Cro-Magnons were very skilled cave painters • Painting of a horse from a cave in France

29. Homo Floresiensis(hobbits) - one meter high - lived in Flores 12,000 yrs ago - Upright posture - 380 cc cranial size (like a chimp)

30. The shapes & sizes of hominid heads can be seen to evolve with time.

31. Australopithecus vs. Modern Australopithecus, 4-3 myrs ago Modern human Chimpanzee

32. Cranial Comparisons Homo Erectus Neanderthal Homo Sapiens

33. Cultural Evolution • With the appearance of Cro-Magnons, • human evolution has become almost entirely cultural rather than biological • Humans have spread throughout the world • by devising means to deal with a broad range of environmental conditions

34. Homo Sapiens100,000 yrs ago Art: Cave Paintings, Venuses Oldest paintings: Chauvet (32,000 yrs old) Peche Merle (15,000 yrs old) Lascaux (17,000 yrs old)