Homo hobbit! “ Flores man ” & patterns of human evolution

1. Homo hobbit! “Flores man” & patterns of human evolution

2. What is EVOLUTION? • Heritable change in a population, over time. • PATTERNS OF EVOLUTION • The various ways in which such change can develop. • This change may ultimately end in Reproductive/ Genetic isolation, and speciation.

3. Anagenesis = change within a population; Cladogenesis = branching (divergence) to produce 2 new species. 2 patterns of speciation:

4. 2 modes of speciation

5. Allopatric speciation: populations are isolated by geographical barriers. No gene flow; speciation occurs through gradual microevolution e.g. adaptive radiation on island groups (kea & kaka, Placostylus in NZ); e.g. H. floresiensis. • Most likely in small, isolated populations: • Founder effect limits size of gene pool; • Genetic drift has greater effects in small populations; • Different environment may generate different selection pressures.

7. The branched evolution of horses

8. http://sci.waikato.ac.nz/evolution

9. http://www.geo.arizona.edu/Antevs/ecol438/lect18.html

10. Divergence Anagenesis (e.g. Pennisi 2006) http://www.staff.amu.edu.pl/~krzychu/ekologiaHS/html/humanFamilyTree.html

11. What drives such changes?

12. At the root of the tree: bipedalism

13. Sahelanthropus tchadensis – 6-7 mya

14. Virtual reconstruction of Sahelanthropus cranium (from Zollikofer et al. 2005)http://www.nature.com/nature/journal/v434/n7034/fig_tab/nature03397_F2.html

15. Orrorintugenensis - 6mya

16. “Lucy” – Australopithecus afarensis – c. 3.2 mya

17. The Laetoli footprints – c. 3.2 mya

18. What sort of natural selection pressure would drive the evolution of bipedalism?

19. Species B TIME Evolutionary change Species A How does this work ????? 1. Mutation (e.g. bipedalism) 2. Advantage (e.g. allows better cooling) 3. Better breeding success (e.g. bipeds have more offspring) 4. Increased % bipeds in population over time 5. Reproductive isolation (biped/quadruped hybrids infertile)

20. Adaptive Radiation: By divergent evolution Eg multiple Australopiths & Homo spp

21. http://www.staff.amu.edu.pl/~krzychu/ekologiaHS/html/humanFamilyTree.htmlhttp://www.staff.amu.edu.pl/~krzychu/ekologiaHS/html/humanFamilyTree.html

22. Kenyanthropusplatyops At least one other hominid species lived in Africa at the same time as A. afarensis:

23. Gracile australopithecines Australopithicus africanus 3 – 2.3 mya

24. Robust australopithecines Paranthropus robustus, boisei, aethiopicus (1.9 –1.5 mya, 2.3 – 1.4 mya, 2.8 – 2.3 mya)

25. Homo habilis(“handy man”)

26. http://www.staff.amu.edu.pl/~krzychu/ekologiaHS/html/humanFamilyTree.htmlhttp://www.staff.amu.edu.pl/~krzychu/ekologiaHS/html/humanFamilyTree.html

27. apes Advances in cranial capacity What selection pressures would drive this? What selection pressures would act against it? http://www.geo.arizona.edu/Antevs/ecol438/lect18.html

28. http://www.sas.upenn.edu/~ptschoen/papers/dissertation/Dissertationch2_files/image009.gifhttp://www.sas.upenn.edu/~ptschoen/papers/dissertation/Dissertationch2_files/image009.gif

29. Pelvic inlet (the birth canal).

30. Homo erectus: found in Africa, Middle East, south & south-east Asia from 1.7mya to 200,000 years ago.

31. Homo neanderthalensis: Neanderthal man • 200,000 – 30,000 years ago • Very-well adapted to prevailing glacial climate

32. Anatomically modern humans – Homo sapiens • From around 198,000 years ago (the Omo skulls)

33. Some of the earliest known modern Homo sapiens; Herto, Ethiopia, 170,000 – 160,000 years ago

35. From Stringer, 2000

36. Chronology of Pleistocene sites (from Stringer, 2000)

38. Homo floresiensis http://www.nature.com.ezproxy.waikato.ac.nz:2048/nature/journal/v431/n7012/fig_tab/nature02999_F1.html

40. http://www.yorku.ca/kdenning/+2140%202005-6/2140-15Nov2005.htmhttp://www.yorku.ca/kdenning/+2140%202005-6/2140-15Nov2005.htm

41. “Flores man” tools Archaeology and age of a new hominin from Flores in eastern Indonesia M. J. Morwood et al. (2004) Nature 431, 1087-1091http://www.nature.com/nature/journal/v431/n7012/fig_tab/nature02956_ft.html

42. From Brown et al. 2004

43. H.sapiens microcephalic H.erectus Pan Comparisons of virtual endocasts H. floresiensisin centre(from Falk et al. 2005) http://www.sciencemag.org/cgi/content/full/308/5719/242/FIG1

44. TIME Convergent Evolution Species X Species A

45. Species Y Species C TIME Convergent Evolution Species X Species A Unrelated species look similar if they live in similar environments/ niche Species Z Species B

46. Example of convergence: Sabre-tooth tigers Marsupial Placental Simpson 1980:70

47. Dwarf elephant & hippo of Malta next to a modern Indian elephant http://geography.berkeley.edu/ProgramCourses/CoursePagesFA2002/geog148/Lectures/Lecture16/MedMap.html

48. Dwarfism in island populations May evolve in response to restricted resource availability. Can happen very rapidly in mammals e.g. Malta’s extinct dwarf elephants evolved from a 4-metre ancestor in less than 5,000 years. Extinct dwarf elephants (Stegodon) were found in the same deposits as the Flores hominins.

49. Mirazon & Foley (2004): • Homo floresiensis provides evidence that: • hominins subject to same evolutionary rules as other mammals exposed to local isolation & small population sizes. • supports the view that our evolutionary tree is a bushy one. • Is consistent with idea that rapid & extreme climatic shifts of last 1 million years  dispersal, isolation, and localised evolutionary change.

50. Figure 1Homo floresiensis in the context of the evolution and dispersal of the genus Homo. http://www.nature.com.ezproxy.waikato.ac.nz:2048/nature/journal/v431/n7012/fig_tab/4311043a_F1.html