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Evidence for Evolution

Evidence for Evolution. Evidence. Ever since Darwin introduced his ideas of natural selection, scientists have been looking for evidence There are many different areas of science that contributed to the evidence for natural selection. Evidence.

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Evidence for Evolution

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  1. Evidence for Evolution

  2. Evidence • Ever since Darwin introduced his ideas of natural selection, scientists have been looking for evidence • There are many different areas of science that contributed to the evidence for natural selection

  3. Evidence • Previous scientists have found evidence for natural selection in the fields of biology, geology, chemistry and physics • Modern day scientists have found evidence for evolution in the field of genetics

  4. Fossils • A fossil is the remains or traces of an organism that died long ago • Fossils most often form when a trace of an organism is buried • Traces of an organism can be a footprint, droppings, eggs, a corpse, etc.

  5. Fossils • Fossils provide us small snapshots of the past that can be used gain knowledge of the past • With the right amount of fossils, we can build a complete picture of the looks, actions and patterns of ancient organisms

  6. Fossils • We can tell how old fossils are in two ways • Superposition is the idea that the deeper a rock formation is, the older it is • If we know that age of a rock formation, we can approximate the age of the fossils in it

  7. Fossils • Carbon dating is a measurement of how old an element is • This allows modern day scientists to see how old the carbon in a particular fossil is • It give a good approximate of the age of fossils

  8. Video • http://www.youtube.com/watch?v=SEDfRy6DQns

  9. Fossil Record • With these fossils we can draw conclusions about the organisms on the earth during different time periods • We can line up the fossils and make a timeline of what organisms looked like and how they changed

  10. Fossil Record • What we see most often in organisms is that they have adapted over time • Species do not randomly appear • Different species come from different adaptations

  11. http://www.youtube.com/watch?v=bYMVNYARBqU • http://www.youtube.com/watch?v=GOKW_7KajCU

  12. Anatomy • Anatomy is the study of structures in the body • Anatomy also provides very compelling evidence for natural selection • Some of the structures of animals are very similar

  13. Anatomy • Compare the two structures that you see here • What is similar about them? • What is different about them?

  14. Anatomy • The structures of both the human hand and the bat hand are very similar • The bones, the joints and the placement of the bones are all similar • This goes across other animals as well

  15. Anatomy • Homologous structures are anatomical structures that originated by heredity • They have a related structure and function • This means they are similar because they were passed down from a common ancestor

  16. Anatomy • Analogous structures have closely related functions but do not derive from similar ancestors • A good example of this would be a bird and a butterfly • They both have wings, but they are built nothing alike • This is because they came from a different ancestor

  17. Anatomy • Sometimes there are structures that are left in organisms long after they have ceased to be useful • These are remains of structures that from ancestors long past • We call these vestigial structures

  18. Anatomy

  19. Biogeography • Darwin noticed something on his voyage that is evidence for natural selection • Darwin noticed that in different parts of the world there are organisms that are closely related but are geographically far apart

  20. Biogeography • These organisms were at one time the same species • When land masses began moving, the species was separated • When the species separated, there were different adaptations • This created the different species we see today

  21. Genetics • With the advent of modern technology we can start to study evolution and natural selection at a genetic level • Modern genetics allows us to make comparisons in DNA to other organisms

  22. Genetics • When we look at DNA and how it is expressed we can see the relationships between organisms • It gives us a better idea of what organisms are closely related, even if they don’t look like each other

  23. Embryo Evidence • Think about all the ways of producing offspring • Are they similar or different? • What is an embryo? • An embryo is an unborn or unhatched organism that is developing

  24. Embryo Evidence • The process of development is similar across many organisms • Many organisms have structures when they develop that are not seen in their final form • For example humans have tails when they develop

  25. Embryo Evidence • Why would these embryos have structures that are not seen in their final forms? • It is because they share common ancestry • The common ancestor had a feature that is not present in the current organism

  26. Video • http://www.youtube.com/watch?v=h3Lkac890c0

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