PRIMATES

1. PRIMATES

2. PRIMATES General characteristics Hands (and feet) adapted for grasping Large brains relative to other mammals Short jaws Forward-looking eyes Binocular vision enhances depth perception Flat nails on digits Relatively well-developed parental care Relatively complex social behavior

3. PRIMATES Earliest primates were likely arboreal Grasping hands and feet are adaptations for hanging on to tree branches Opposable thumb and big toe Homo is the only extant primate lacking an opposable big toe

4. PRIMATES Modern primates divided into two subgroups Prosimians �Premonkeys� Anthropoids Monkeys and apes (including humans)

5. PRIMATES Prosimians �Premonkeys� e.g., Lemurs, lorises, pottos, tarsiers, etc. Probably resemble early arboreal primates

6. PRIMATES Prosimian primates and anthropoid primates diverged at least 45 million years ago

7. PRIMATES Anthropoids Monkeys and apes, including humans Oldest anthropoid fossils 45 million years old New and old world monkeys diverged by 40 million years ago

8. PRIMATES All New World monkeys are arboreal Some Old World monkeys are arboreal, and some are ground-dwelling Most of both groups are diurnal and social

9. PRIMATES Four genera of apes Hylobates Gibbons Pongo Orangutans Gorilla Gorillas Pan Chimpanzees and bonobos

10. PRIMATES Modern Apes Evolved from Old World monkeys 25 � 30 million years ago Confined exclusively to tropical regions of the Old World

11. PRIMATES Modern Apes Larger than monkeys Gibbons are an exception Brains proportionally larger than monkeys

12. PRIMATES Modern Apes Long arms, short legs, and no tails All are capable of brachiation Only gibbons and orangutans are primarily arboreal Social organization is variable Gorillas and chimpanzees are highly social

13. HUMAN ANCESTRY Humans and apes have shared ancestry for all but the last few million years Paleoanthropology focuses on this short period of time The study of human origins and evolution

14. HUMAN ANCESTRY When measuring against the history o the Earth, humans are very recent additions Perhaps we are not quite as important as we might like to believe

15. HUMAN ANCESTRY "Humans are not the end result of predictable evolutionary progress, but rather a fortuitous cosmic afterthought, a tiny little twig on the enormously arborescent bush of life, which if replanted from seed, would almost surely not grow this twig again." - Stephen Jay Gould

16. HUMAN ANCESTRY Terminology Anthropoid Monkeys, apes, and humans Hominoid Great apes and humans Hominid Humans and their bipedal relatives

17. DEAR DR. LAURA� Did we evolve from chimpanzees? No. Humans and chimpanzees evolved from a common ancestor, which was neither a chimpanzee nor a human.

18. DEAR DR. LAURA� Did we evolve from monkeys or apes? We did not evolve from any present day monkey or ape. However, the common ancestor we share with chimpanzees would certainly be considered an ape, and common ancestors of both humans and monkeys would certainly be considered monkeys themselves.

19. DEAR DR. LAURA� If we evolved from apes, then why are there still apes? This misconception is due to the tendency of people to think of evolution as a linear progression toward some goal, which is certainly not the case. Adaptive radiations give rise to multiple species stemming from a single species.

20. DEAR DR. LAURA� Was the production of humans the ultimate goal of primate evolution? This view is simply testament to the arrogance and self importance of humans. Lets get over it, people; we�re not quite that important. �Nuff said.

21. 30 � 35 M.Y.A. Early anthropoids were still tree dwellers

22. 20 M.Y.A. Indian plate collided with Asia Thrust up Himalayans Climate became drier Forests (present Africa & Asia) shrunk Increased savanna (grassland) with fewer trees Some anthropoids increasingly exploited this new habitat Decreased reliance on arboreal environment

23. ~15 M.Y.A. Last common ancestor of gibbons and humans And of gibbons and chimps, gibbons and gorillas, and gibbons and orangutans, for that matter

24. ~10 M.Y.A. Last common ancestor of orangutans and humans And of orangutans and chimps, as well as orangutans and gorillas, for that matter

25. ~8 M.Y.A. Last common ancestor of gorillas and humans And of gorillas and chimps, for that matter

26. ~5 - 7 M.Y.A. Last common ancestor of chimpanzees and humans

27. CLOSEST RELATIVE? What is our closest living relative? What species is the chimpanzee�s closest living relative? � the gorilla�s? � the orangutan�s?

28. HUMAN EVOLUTION Major features of human evolution Increased brain size Altered jaw shape Bipedal posture Reduced sexual dimorphism Extended parental care

29. HUMAN EVOLUTION Major features of human evolution Increased brain size 400 � 450 cm3 6 million years ago Similar to modern chimpanzee 1300 cm3 today

30. HUMAN EVOLUTION Major features of human evolution Altered jaw shape Hominoid ancestors had longer jaws �Prognathic jaws� Feature retained by chimpanzees Jaws shortened during human evolution ? Flatter face and pronounced chin

31. HUMAN EVOLUTION Major features of human evolution Bipedal posture Hominoid ancestors walked on four limbs when on the ground Trait retained by modern apes Bipedal posture evolved > 4 million years ago �Hominids� Cause of this change? Various hypotheses, but still unclear Some of these hypotheses are beautiful examples of cultural bias affecting scientific thought

32. HUMAN EVOLUTION Major features of human evolution Reduced sexual dimorphism Difference in secondary sexual characteristics reduced between males and females e.g., Male: female size ratios Orangutan 2 Gorilla 2 Chimpanzee 1.35 Human 1.2

33. HUMAN EVOLUTION Major features of human evolution Extended parental care Enhanced parental care and an enlarged brain enhance learning Associated with behavioral complexity of humans

34. HUMAN EVOLUTION What does the fossil record tell us about human evolution? Many hominid fossils have been found All but most recent are from eastern or southern Africa These fossils represent many different hominid species Some hominid species coexisted with others

35. HUMAN EVOLUTION Our hominid ancestry is branching, not linear Multiple species of hominids often coexisted Most died out, but we are still here for now

36. HUMAN EVOLUTION Bipedalism evolved 4 � 6 million years ago Homo and Australopithecus genera best studied Bipedalism predated increased brain size

37. AUSTRALOPITHECUS The first australopithecine was discovered by Raymond Dart in 1924 in a South African quarry Identified as an early human Australopithecus africanus �Southern ape from Africa� Fully erect, with a brain much smaller than ours The evolution of bipedalism predates the vastly increased brain size of humans

38. AUSTRALOPITHECUS How can one establish bipedalism from a skull? �a femur? �pelvic bones?

39. AUSTRALOPITHECUS In 1974, David Johanson discovered a 40% complete Australopithecus skeleton �Lucy� Afar region of Africa (Ethiopia) Australopithecus afarensis From �Afar� 3.24 million year old Age determined by radioactive dating Slightly older than A. africanus

40. AUSTRALOPITHECUS In 1974, David Johanson discovered a 40% complete Australopithecus skeleton �Lucy� Humanlike posture, small brain Bipedalism established by skull and pelvic bones Human-like below the neck Ape-like above the neck

41. AUSTRALOPITHECUS Additional A afarensis fossils have been found Many in the 1990s Longevity of the species at least 1 million years

42. AUSTRALOPITHECUS Australopithecus anamensis Unambiguously human Lived >4 million years ago

43. AUSTRALOPITHECUS Other putative hominids 6 million years old Very close to chimpanzee/hominid branching

44. AUSTRALOPITHECUS Which australopithecines led to Homo? Which were evolutionary dead ends?

45. AUSTRALOPITHECUS A afarensis underwent an adaptive radiation ? Robust australopithecines Powerful jaws, large teeth Adapted for grinding and chewing hard foods Evolutionary dead end ? Gracile australopithecines Similar to A. afarensis Lighter feeding equipment Adapted for softer foods Ancestral to homo

46. HOMO Homo habilis �Handy man� First discovered in 1964 Louis Leakey, et al. Earliest fossils placed in the genus Homo 2.5 � 1.6 m.y.a.

47. HOMO Homo habilis Clear signs of modern hominid skull characteristics Less prognathic jaw Larger brain 600 � 70 cm3 First known use of manufactured stone tools

48. HOMO Homo erectus 1.8 � 0.5 million years ago Sometimes split into Home ergaster (earlier) Homo erectus (later end)

49. HOMO Homo erectus Taller than Homo habilis Larger brain Averaging 1,100 cm3 Reduced sexual dimorphism Male:female size = 1.2 Same ratio as today May offer insight into social structure

50. HOMO �Turkana boy� 1.6 million years old Larger brain Likely over 900 cm3 by adulthood Classified as Homo ergaster or Homo erectus

51. HOMO Homo erectus First hominid species to migrate out of Africa Colonized Asia by 1.5 m.y.a. Spread into Europe (timing less certain)

52. HOMO Homo sapiens Evolved from H erectus or H ergaster In Africa alone or multiregionally?

53. HOMO Homo sapiens Mitochondrial DNA (mtDNA) can be used as a molecular clock Human genetic divergence ~100,000 years ago Supported my nuclear genetic markers esp., Y chromosome �Out of Africa�

54. HOMO Neanderthals �First� discovered in Germany�s Neander Valley 1856 (1829 elsewhere) Lived 200,000 � 40,000 years ago Brains as large as ours Shaped differently Prominent brow ridge Sloping forehead Occipital bun

55. HOMO Neanderthals Species or subspecies? Homo sapiens neanderthalensis Homo neanderthalensis

56. HOMO Neanderthals Contemporary to more modern Homo sapiens �Cro-Magnon man� Ultimately disappeared Why?

57. HOMO Neanderthals mtDNA analysis of Neanderthal DNA Extracted from bone Very different from modern H sapiens It is very unlikely that Nenderthals contributed significantly to our gene pool

58. HOMO Sure, maybe we are smart, but �.. Diverse prokaryotes are ubiquitous Arthropods outnumber all known species combined There are more species of bony fishes alive today than all other vertebrates combined Dinosaurs ruled the earth for much, much, much longer than we did We are not as successful as many other groups