Evidence for Evolution (Chapter 18 and…)

1. Evidence for Evolution(Chapter 18 and…) The real fossil bones of the walking and swimming whale, Ambulocetus natans, are spread out in this picture with a sledgehammer for scale. The skeleton was about 12 feet long and is about 49 million years old. It was found in Pakistan.

3. Evidence for Evolution 1. Remains of living organisms can be trapped and preserved in… • resins that turn to amber • frozen in ice or snow • in sediments that produce fossils (most important) • date rocks and fossils using radioactive isotopes • whether an organism is preserved greatly depends on the local environment in which it died • heated debate exists regarding the species identification for new specimens based only on fossil record • therefore, paleoanthropologists often use the term paleospecies instead of species

4. Scientists look for paleontological evidence– specifically transitional fossils • example: Archaeopteryx -- transitional form between birds and reptiles • microraptor • Homo habilis • Lucy

5. Evolving Ideas: How Do We Know Evolution Happens? http://www.pbs.org/wgbh/evolution/library/11/2/e_s_3.html

6. 2. Biography/Geographical Distribution • the study of the distribution of living things (or fossils) over the Earth • a heated debate exists on human evolution • research based on DNA supports the “Out Of Africa” hypothesis that all modern humans stem from a single group of Homo sapiens who emigrated from Africa 2,000 generations ago and spread throughout Eurasia over thousands of years • these settlers replaced other early humans (such as Neanderthals), rather than interbreeding with them

10. 3. Comparative Embryology/Anatomy • embryos of vertebrates look similar • useful when don’t have much of a fossil record • almost all mammals have seven cervical (neck) vertebrae and gill arches • Ontogeny recapitulates phylogeny • the idea that the embryonic development is similar to evolution

12. German biologist, naturalist, philosopher, physician, professor and artist who discovered, described and named thousands of new species (see below), mapped a genealogical tree relating all life forms, and coined many terms in biology, including phylum, phylogeny, ecology and the kingdom Protista (details below). Haeckel promoted Charles Darwin's work in Germany and developed the controversial "recapitulation theory" claiming that an individual organism's biological development, or ontogeny, parallels and summarizes its species' entire evolutionary development, or phylogeny: "ontogeny recapitulates phylogeny" (see below).

13. Homologous structures • have a common evolutionary origin, but can look quite different and have different functions • ex. forelimbs of birds, bat, horse, humans...

15. Analogous structures • have similar functions, may appear similar, yet presumed to have different evolutionary origins • ex. wings of an insect and bird wings of bat, bird (though the BONES are homologous!), insect:

18. 4. Biochemistry • all living organisms use DNA/RNA as genetic material • all (except bacteria) use the same 20 amino acids to make their proteins • differences of a.a. sequences accumulate (mutations) at a constant rate and therefore can be used as an evolutionary clock • the more differences in proteins, the less likely organisms are “related”

19. 4. Selective Breeding of Domesticated Animals • artificial selection When selective breeding goes too far The government has confirmed that it will use a report on the selective breeding of freak pets - including fancy goldfish - to shape the Animal Welfare Bill.