Evolution II.

1. Evolution II.

2. Dating of fossils • Relative • Absolute

3. Relative dating

4. Absolute dating • Radiometric dating

5. 1,0 decay product Share of isotope 0,5 isotope 0 t Half-life time Principle of radiometric dating

6. Mesozoic K-T Border (66-65 mil.y.): mass extinction

7. Chixculub Crater (Mexiko) Site of colision with an asteroide measuring 10-20 km across

8. Kenozoic Homo sapiens sapiens

9. Cladogram Cladistics • A method of analyzing the evolutionary relationships between groups to construct their family tree. Phylogenetic relationship between organisms is derived from the similarity of certain characters. • Result of cladistic analysis – cladogram.

11. Simple cladogram of mammals

12. A cladogram derived from the molecular data (DNA sequence)

13. Homo sapiens sapiens Homo „sapiens“ neanderthalensis Homo erectus Australopithecus. africanus Homo habilis Homo heidelbergensis Australopithecus afarensis Ardipithecus ramidus Possible fylogenetic relationships of hominides I. Quarternary Time (milions of years) Tertiary

14. Possible fylogenetic relationships of hominides II.

15. Kenyantropus

16. Australopithecus africanus

17. Australopithecus africanus Skull of „Taung child“ – found in south Africa

18. Australopithecus afarensis

19. Autralopithecus afarensisskeleton„Lucy“

20. Australopithecus walked upright (bipedal) Footsteps of A.afarensis (Laetoli, Tanzania)

21. Australopithecus afarensis

22. Homo habilis

23. Homo erectus the first hominide living outside Africa

24. Homo erectus

25. Homo erectus

26. Homo heidelbergensis

27. Homo sapiens sapiens Homo „sapiens“ neanderthalensis Homo erectus Australopithecus. africanus Homo habilis Homo heidelbergensis Australopithecus afarensis Ardipithecus ramidus Possible fylogenetic relationships of hominides Time (milions of years)

28. Homo neanderthalensis

29. Homo neanderthalensis

30. Homo neanderthalensis

31. Homo neanderthalensis X Homo sapiens

32. Modern Homo sapiens Lascaux cave (France) – paintings of wild horses and aurochs (17 000 years ago).

33. http://www.modernhumanorigins.com/

34. About the origin of Homo sapiens • Monocentric models • Homo sapiens evolved in one site (probably in the Africa) – out-of-Africa theory • Polycentric models (multiregional evolution) • Homo sapiens evolved independently in a few different sites. Modern humans originated of crossbreedind of these different strains.

35. Out-of-Africa Theory

36. Mitochondrial Eve • The rate of mutations in the mitochondrial genome (mtDNA) is constant – roughly 1/1500-3000 years. • Comparison of these mutations could explain differences on possible relationship between different human populations. Its also possible to estimate the time of evolutionary division of their ancestors. • mtDNA studies showed that the modern humans (Homo sapiens sapiens) differed from other species of the genus Homo before some 150 – 200 thousands of years. Homo sapiens originated from a small group of females (or only one female) – such called „mitochondrial Eve“, which delivered to us her mitochondrial genes. • „Eve“ lived probably in Africa. It supports the hypothesis, that the whole mankind originated from only one ancestor (i.e. „out-of-Africa theory).

37. What hapenned with Homo neanderthalensis? Theories • Homo sapiens evolved from H. neanderthalensis • H. sapiens and H. neanderthalensis were different species, but H.neanderthalensis failed in competition with H. sapiens • (H.n. was a trophy of H.sapiens) • There was numerous crossbreeding between H. sapiens and H. neanderthalensis. Current human population consist of descendants of the both of species.

38. Results of the mtDNA studies? • Hypervariable sequences HVR I a HVR II of the mtDNA (aDNA) isolated from the fossil materials were analyzed. • Intraspecific variability within the population of the modern humans reaches maximum only 11pb. • Differences in HVR squences between the modern human and H. neanderthalensis are 35 pb. It could be explained as a interspecific difference.