1. The Age of Things: Sticks, Stones and the Universe Potassium, Argon, DNA and Walking Upright http://cfcp.uchicago.edu/~mmhedman/compton1.html

2. Proconsul

4. Sivapithecus Australopithecus Proconsul WARNING! Astrophysicist talking about Paleoanthropology

5. Proconsul Sivapithecus Australopithecus

6. Bipedalism is a uniquely human trait

7. Time

8. Australopithecus afarensis Australopithecus africanus Paranthropus robustus Paranthropus bosei Homo habilis Homo erectus Homo sapiens Different Types of Hominids

9. Australopithecus afarensis Australopithecus africanus Paranthropus robustus Paranthropus bosei Homo habilis Homo erectus Homo sapiens Hominids 0 1 mya 2 mya 3 mya 4 mya (mya = millions of years ago)

10. All these hominids could walk on two legs Australopitchecus afarensis

11. Recent hominid finds Sahelanthropus tchadensis Orrorin tugenensis Age of the fossils Time when hominids first became bipedal Based on Geological DataBased on Molecular Data

12. Dating the Fossils with the Potassium-Argon method

13. Carbon 14Nitrogen 14 electron neutrino Potassium 40 Calcium 40 electron neutrino Potassium-Argon Dating ProtonNeutron

14. Potassium 40 Argon 40 electron neutrino Potassium 40 Calcium 40 electron neutrino Potassium-40 has two ways it can decay 90% 10%

15. R R= Current amount of Potassium-40 Original amount of Potassium-40 Half-Life of Potassium-40 is1.25 billion years

16. Potassium-40 Argon-40 Calcium-40 Potassium-40 decay in molten rock

17. Potassium-40 Argon-40 Calcium-40 Potassium-40 decay in solid rock

18. Potassium-40Calcium-40 The Rock Today Argon-40

19. Potassium-40Argon-40Calcium-40 Potassium 40 Calcium-40 The Original Rock The Rock Today

20. The East African Rift System

21. Red Circles=Earthquakes Green triangles=Volcanoes

22. 2.5 Million Years Ago 3 Million Years Ago

23. Ardipithecus ramidus

25. Recent hominid finds Sahelanthropus tchadensis Orrorin tugenensis Age of the fossils Time when hominids first became bipedal Based on Geological DataBased on Molecular Data

26. Molecular Dating Methods C C C A A G A G T T WARNING! Astrophysicist talking about Molecular Biology

27. Molecular Dating Methods C C C A A G A G T T

28. Mutations in DNA CCCAAGAGTTCACTTCCAAGAGTT CCCATGAGTTCCCAAGAGTTSubstitution CCCAATCCCAAGAGTTDeletion GAGTGAGT OriginalCCCAAGAGTTCCCAAGAGTT Insertion CCCAAGCTTGACCAAGAGTT Inversion

29. CCCAAGAGTT CCCA T GAGTT CCCAAGAGT G TIME The accumulation of mutations over time CCCAAGAGTT G CCA T GA A TT CC TC AGAGT G

30. TIME The accumulation of mutations over time CCCAAGAGTT G CCA T GA A TT CC TC AGAGT G C A C C AGAGT G CCC C AGAGT G

31. Could mutations accumulate at a constant rate ? 1. Mutations occur at the same rate in all animals 2. Mutations are equally likely to be passed on in all animals Possible, mutations are due to biochemical processes that are almost identical in different animals Unlikely, if mutations affect physical characteristics of animal (Rate depends on environment, etc.) True if mutations have no impact on the health or appearance of the animal Neutral or “Silent” mutations Two conditions must be met

32. CCCAAGAGTT CCCA T GAGTT CCCAAGAGT G TIME The accumulation of mutations over time CCCAAGAGTT G CCA T GA A TT CC TC AGAGT G

33. CCCAAGAGTTCCCAAGAGTT CCCA T GAGTTC G CAAGA A TTCCCAA A AGT G CCCAAGA C TT TIME 6 differences The accumulation of mutations over time

34. CCCAAGAGTTCCCAAGAGTT CCCA T GAGTTC G CAAGA A TTCCCAA A AGT G CCCAAGA C TT TIME Using mutations to establish relationships CCCAAGAGT G CCCA T GA C TT

35. Time

36. CCCAAGAGTTCCCAAGAGTT CCCA T GAGTTC G CAAGAGTT CCCA T GAGTTCCCAAGAGTTCCCAAGAGT G CCCAAGAGTT CCCAAGAGT G CCCAAGA C TT CCCA T GAGTTC G CAAGA A TTCCCAA A AGT G CCCAAGA C TT TIME 2 differences 4 differences 6 differences The accumulation of mutations over time

37. TIME The environment constrains certain mutations

38. Identifying “useful” regions of DNA

39. Proconsul

40. Molecular Dating in Humans and Apes

41. TAGGATCGATATAACATAGCCGAACGAGACTATGGCTAGAGAGCATAGAC TAGGATCGATATAAGATAGCCGATCGAGACTATGGCTAGAGAGCATAGAC TACGATCGATATAAGATAGCCGAAGGAGACTATGGATAGAGAGCATAGAC TAGGATCGATATAAGATAGCCGAACGAGACTATGGCTAGAGTGCATAGAC

42. ChimpGorillaOrangutan Human1.24%1.62%3.08% Chimp1.63%3.12% Gorilla3.09% Human ChimpGorillaOrangutan

43. ChimpGorillaOrangutan Human1.24%1.62%3.08% Chimp1.63%3.12% Gorilla3.09% Human ChimpGorillaOrangutan 1% 2% 3%

44. Human ChimpGorillaOrangutan 1% 2% 3% Sivapithecus More than 12 million years old Calibrating the molecular clock

45. Human ChimpGorillaOrangutan 1% 2% 3% Sivapithecus Proconsul Calibrating the molecular clock Proconsul Sivapithecus

46. Human ChimpGorillaOrangutan 1% 2% 3% Sivapithecus Proconsul 15 10 5 Millions of years ago Calibrating the molecular clock Proconsul Sivapithecus

47. Ardipithecus ramidus Estimated time when humans and chimps last had a common ancestor

48. Human ChimpGorillaOrangutan 1% 2% 3% Sivapithecus Proconsul 15 10 5 Millions of years ago

49. Next Time: Molecular Dating and the Many Kinds of Mammals