1. Natural Selection in Animals Activity
Who Gives a Hoot?

2. Written Response #7
Evidence for evolution: what clues have scientists used to study evolution?
What pieces of evidence do you think are important?

3. Evidence Biochemical (molecular) evidence:
DNA similarities:
Human Sequence: AGG CAT AAA CCA ACC GAT TAA
Ape sequence: AGG CCC CCT CCA ACC GAT TAA
Chimp sequence: AGG CCC CCT CCA ACC AGG CCA
Chromosomal similarities (karyotypes)
Humans: 46 chromosomes
Chimpanzees: 48 chromosomes (Chimpanzee’s chromosome pair #2 and #3 fuse to resemble human’s pair #2

4. Evidence Fossil record:
Relative Dating: exact age of fossil cannot be determined, only the order of appearance compared to fossils found in nearby rocks.
Older fossils are found in deeper rock layers
Absolute (Radioactive) Dating: gives a more exact age using natural decay of radioactive isotopes in organisms.

5. Evidence Embryology: similarities among developing embryos
Humans for example have gills when developing

6. Evidence
Homologous structures: structures derived from the same tissues but are used differently in different organisms
Indicate: common descent
The structures show morphological similarities among organisms
Similar bone origins
Used differently and appear differently

7. Evidence
Analogous structures: structures that perform the same function (ex: flying) but are different anatomically (ex: bird wing versus butterfly wing)
Supports evolution in similar habitats instead of from a common ancestor

8. Evidence
Vestigial structures: may have once had a function but have evolved to be useless over time
May represent a link to a previous ancestor
Examples: whale’s hip bones, human appendix, human tailbone