Evidence of Evolution

1. Evidence of Evolution

2. Evidence of Evolution • Fossil Record • Homologous Body structures • Similarities in Embryology • Biochemical Evidence

3. Evidence of Evolution:The Fossil Record • Fossil record provides evidence that living things have evolved • Fossils show the history of life on earth and how different groups of organisms have changed over time

4. Relative vs. Absolute Dating

5. Relative Dating • Can determine a fossil’s relative age • Performed by estimating fossil age compared with that of other fossils • Drawbacks – provides no info about age in years

6. Absolute Dating • Can determine the absolute age in numbers • Is performed by radioactive dating – based on the amount of remaining radioactive isotopes remain • Drawbacks - part of the fossil is destroyed during the test

7. Radiometric dating uses decay of unstable isotopes. • Isotopes are atoms of an element that differ in their number of neutrons. • A half-life is the amount of time it takes for half of the isotope to decay.

8. Primate Fossils Australopithecus Homo erectus Homo sapien

9. Primate Bone Structure

10. Evidence of Evolution:Homologous Body Structures Turtle • Structures that have different mature forms but develop from the same embryonic tissues Ex: Wing of bat, human arm, leg of turtle Alligator Bird

11. Molefoot Batwing Human hand Evidence of Evolution:Homologous Structures • Features that are similar in structure but appear in different organisms and have different functions. • Strong evidence for common ancestor. • Ex: forelimbs of humans, bats and moles.

12. Analogous Structures • Structures that perform a similar function. • Not evidence of common ancestry.

13. Vestigial Structures • Remnants of organs or structures that had a function in an early ancestor. • Ex: Ostrich wings, used for balance but not flight • Ex: Humans’ appendix

14. Evidence of Evolution:Similarities in Embryology In their early stages of development, chickens, turtles and rats look similar, providing evidence that they shared a common ancestry.

15. Embryological Development

16. Evidence of Evolution:Biochemical Similarities • Scientists study nucleotide sequences in DNA and proteins in different organisms to determine ancestry. • If the organisms are closely related they will have similar sequences of nucleotides in their DNA and arrangement of amino acids in proteins.

17. Evidence of Evolution:Biochemical Similarities The more similar the amino acid sequence, the more closely related the organisms are.