Human Evolution

1. Human Evolution

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

3. Important Vocabulary Paleoanthropologist • Scientist who studies fossil evidence of human evolution. Homininds • Group that includes humans and their immediate ancestors.

4. Background • It is very rare to find a complete skeleton of a fossilized hominid. • Scientists need to look at many different things to try and piece together the puzzle of human evolution.

5. Background Cont’d • When hominid fossils are found, several important characteristics can help determine origin and lifestyle of the species. • Did organism walk upright? • Curvature of spine, position where spine attaches to skull and shape of pelvis • Brain size? • Examine skull fragments • Diet? • Wear and tear on fossilized teeth • How and where did it live? • Fossils found in same area & environment found

6. Primates • 2 Divisions of Primates • 1. Anthropoid primates • 2. Prosimean primates • Characteristics: • Flat Nails (no claws) • Prehensile hands and feet (grasping) • Color vision and depth perception

7. Anthropoid Primates • Include: • marmosets • Monkeys • Apes • Humans • Brain size • Large relative to their body size • Opposable thumbs • Similar dental formula • number and arrangement of teeth

8. HUMANS • Bipedalism – Ability to walk on 2 feet • Aligned toes = Bipedalism • Enlarged brain =Vertical face • Areas for speech in the brain • S- shaped spine • Bowl-shaped pelvis

10. Prosimean primates • Include: • Lemurs • Lorises • Tarsiers

11. Tarsier Skeleton

12. Hominids • Hominids include humans and extinct humanlike primates • The oldest known hominid fossils are between 6 and 7 million years old • First fossils found in Africa

13. Australopithecus • Oldest known genus of hominids • Lived more than 4 million years ago • Knee joints- Allow bipedalism! • Australopithecus anamensis • Australopithecus afarensis – believed to have given rise to: • A. africanus • A. robustus • A. boisei • more than 1 million years ago NOT ancestral to modern humans!

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

15. A. africanus • !

16. A. boiser • !

17. Discovery of Lucy! • Fossils of nearly half complete early hominid Australopithecus afarensis • suggests hominids became bipedal before their brains began to dramatically enlarge

18. Ardipithecusramidus • Recent discovery • Not clear whether it was bipedal • 4.4 million years old

19. Existence of hominid species not ancestral to modern humans implies… • Hominid phylogenetic tree is very branchy in appearance • Representing species died out, leaving no descendants.

20. Early Members of the genus HomoH. habilis & H. erectus • Ancestors to modern humans • Larger brains than australopithecines • May have had speech • Started to develop tools Homo erectus Homo habilis

22. Cranial Comparisons Homo Erectus Neanderthal Homo Sapiens

23. Neanderthals • For years, the thinking among anthropologists was that homo sapiens, being superior to Neanderthal man, ran him off the planet. More recently, that view has been discarded and the picture become more complicated. For one thing, Neanderthals may have mixed with the ancestor of modern man, which means that we could be carrying Neanderthal genes.

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

25. Cro-Magnons • Cro-Magnons coexisted with Neanderthals in Europe and the Middle East for as many as 50,000 years • Cro-Magnons had domed heads, smooth brows, and prominent chins • 30,000-year-old Cro-Magnon artifacts include: • Bone flutes • Ivory sculptures • Evidence of elaborate burial ceremonies

26. Cro-Magnon Cave Painting

27. Homo sapiens • Evolved about 800,000 years ago • A) Neanderthals • Were early Homo sapiens • They may be ancestral to modern humans OR • They may have died out and been replaced by modern humans

28. Some hypotheses: • 1. some anthropologist think H. sapiens evolved in PARALLEL from populations of H. erectus all over the world. (interbreeding) • 2. some anthropologists propose that H. sapiens DESCENDED from H. erectus in Africa and then dispersed across Earth.

29. Evolution of Modern Humans

30. Human Evolution

33. Piltdown Man (1912)Charles Dawson fake 1953preceding Neanderthals • *

34. Waves of Hominid Emigration • Two hypotheses have been proposed for the evolution of Homo sapiens • “African replacement” hypothesis • Also called Out of Africa, Recent-African-Origin • “Multiregional origin” hypothesis

35. “African Replacement” Hypothesis • Members of the genus Homo made repeated long-distance migrations out of Africa beginning 1.8 million years ago • H. sapiens emerged from Africa about 150,000 years ago and spread across the Near East, Europe, and Asia • The dispersing H. sapiens populations replaced all other hominids

36. Evolution of Modern Humans

38. “Multiregional Origin” Hypothesis • H. erectus emerged from Africa 1.8 million years ago and spread across the Near East, Europe, and Asia • Continued migrations and interbreeding occurred among widespread H. erectus populations • Regional populations of H. erectus evolved into H. sapiens

39. Evolution of Modern Humans