Human evolution

1. Human evolution Aditi Pai

2. "Hominid" refers to members of the human family, Hominidae, which consist of all species from the point where the human line splits from apes towards present day humans. Habitual bipedal locomotion (movement on two legs), an upright position, and a large brain that has lead to: tool use, language, and culture characterize hominids.

3. Human evolution • History • Important stages in human evolution • Theories of human evolution • ‘Human Characteristics’ • Are we still evolving?

4. History • 1856-Neander Valley • Discovery of a skull that was not quite human

5. 1859 – Darwin publishes ‘The Origin of Species’ • 1871- Darwin predicts that ancestors of humans would be found in Africa

6. C D B A • Up till 1930s • Humanity evolved in Europe • 1950s--1960s • Many significant fossils discovered Bush model • ABCD Linear model

7. 1970s – present • more fossils • molecular techniques • ‘tree model’ of human evolution

8. Current Controversy 6-7 m y old fossil Earliest bipedal hominid? Sahelanthropus tchadensis

10. Important stages in human evolution • 3.2 million years ago • 3 million years ago • 2 million years ago • 1 million years ago • 200, 000 years ago • 150, 000 years ago

11. "Hominid" refers to members of the human family, Hominidae, which consist of all species from the point where the human line splits from apes towards present day humans. Habitual bipedal locomotion (movement on two legs), an upright position, and a large brain that has lead to: tool use, language, and culture characterize hominids.

13. 3.2 mya: The southern ape of afar • Fossil: • “Lucy” (discovered 1974, Ethiopia) • Australopithecus afarensis Male

14. Fossil of “Lucy” Female

15. Australopithecus afarensis • Habitat: savannah and woodland • Food: leaves, fruit, seeds, nuts, termites and eggs, grasses (?) • Physical characteristics: • low forehead, flat nose, no chin • small brain • long dangly arms, short legs • facultative bipedal (upright on ground but could dangle from branches) • sexually dimorphic

17. Paranthropus boisei Homo habilis

18. 3 mya: Paranthropus boisei • Habitat: open terrain • Food: nuts, roots and tubers • Physical characteristics: • enormous jaw with chewing muscles, • large back teeth, small front teeth • specialized as vegetarians • Not direct human ancestors

19. 3 mya: Homo habilis-the ‘handy man’ • Habitat: open terrain • Food: Scavenged for meat • Physical characteristics: • small jaw and teeth • shorter arms • increase in brain size (because of carnivorous diet and mode of feeding) • capable of speech

20. Oldowan Tools Made tools

22. Human migration • 1.9 mya humans began to leave Africa to other continents

23. Homo ergaster

24. 2 mya: Homo ergaster • Habitat: dry -hot habitat • Food: scavenger for meat • Physical characteristics: • Tall with long limbs • Smooth and dark skin • Temperature regulation through sweating • Narrow pelvis (lead to narrow birth canal) • Mothers needed support of partner and group to raise babies

25. Acheulean bifaces

26. Homo erectus

27. Homo erectus • brain, almost human size • stocky, human-like body (larger than Homo habilis) • Java, China, and Africa • use of fire • increased but infrequent group hunting • language • crude shelters and some migration to colder areas • used tools

29. Homo heidelbergensis

30. 1mya: Homo heidelbergensis • Food: hunted for meat • Physical characteristics: • Large brain • Tall • Direct ancestors of Homo sapiens

31. Boxgrove tools H.heidelbergensis made Hand axes, wooden spears etc.

33. 200,000 ya: Homo neanderthalensis male female

34. 200,000 ya: Neanderthal man • Habitat: cold • Food: hunted for meat • Physical characteristics: • Large face with massive ridges • No chin • Short stocky body (conserve heat) • Muscular • Language • Social relationships important

35. What happened to the Neanderthals? • Extinct 28, 000 ya • Competition from Homo sapiens?

37. Homo sapiens • 120, 000 ya • Physical characteristics: • Eyebrow ridge small or absent • Prominent chin • Tools --antler, bone, stone • Clothing, jewelry, artwork, musical instruments

38. Theories of human evolution • Humans evolved in sub-Saharan Africa and spread from there or • Humans evolved independently in several places around the globe

39. Out of Africa hypothesis • Homo sapiens evolved in a single speciation event in Africa ~ 250, 000 ya • Migrated to other regions, replaced Homo erectus

40. Multi-regional hypothesis • Local populations of Homo erectus evolved into Homo sapiens • Mixed genes • Retained local characteristics

41. Support for multi-regional hypothesis • No break in culture in S.E Asia • Can explain the occurrence of regional characters

42. Races • Original skin color- black • Divergence from original black color to many different colors

43. How different are the races? • No genetic discontinuities between races • Genetic differences between races only 10% of genetic diversity among humans • No evidence for major biological differences

44. Support for ‘out of Africa’ hypothesis 1. Level of diversity in maternally inherited mitochondrial DNA of humans from around the world highest among Africans

45. Support for ‘out of Africa’ hypothesis 2. Based on genetic diversity all non-Africans descended from a small band of humans that left Africa ~ 100, 000 ya

46. Support for ‘out of Africa’ hypothesis 3. The Y-chromosome too shows no sign of any non-African DNA

47. Human migration • Australia --- ~60,000 ya • Europe --- ~70,000 ya • Near East --- ~90,000 ya • Africa --- ~130, 000 ya

48. Who were the first Americans? • 13,000 ya • Crossed Bering Strait

49. Human characteristics • Bipedal gait • Big brain • Tool making • Social relationships • Art • Culture

50. Bipedalism • When? • Before Australopithecines • Advantages: • Freed hands to carry objects • See predators better in grasslands • Access to foods not previously available • Carry children • Protection from sun in grasslands