Evidence for Evolution
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Transcript of Evidence for Evolution
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Evidence for Evolution
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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
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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
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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.
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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
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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
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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
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Video
• http://www.youtube.com/watch?v=SEDfRy6DQns
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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
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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
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• http://www.youtube.com/watch?v=bYMVNYARBqU
• http://www.youtube.com/watch?v=GOKW_7KajCU
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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
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Anatomy
• Compare the two structures that you see here
• What is similar about them?
• What is different about them?
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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
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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
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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
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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
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Anatomy
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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
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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
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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
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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
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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
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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
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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
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Video
• http://www.youtube.com/watch?v=h3Lkac890c0