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Chapter 13 Notes Continued
Evidence of Evolution
There are five modern day evidences that support the work of
Darwin
• Age of the Earth
• Fossil evidence
• Anatomical evidence
• Biochemical evidence
• Embryological evidence
1. Age of the Earth
• While many bible scholars estimated the earth to be 30,000-40,000 years old, Darwin predicted the Earth to be Millions of years old. (Deep Time)
• Modern evidence suggests the earth to be 4.6 Billion years old
2. Fossils
• Fossils are the remains or traces of remains of organisms that lived long ago
• Typically are the bones, teeth or shells of past animals
• Imprints and casts are other types of Fossils
• Most fossils are formed in sedimentary rock
Fossils
• Age is important! Fossils can be “dated” by radioisotopes of Carbon-14, Uranium-238 or Potassium-40.
• The half-life of these chemicals is the amount of time it takes for that chemical to decay by 50%
• Half-life for Carbon-14 is 5,730 years
Fossils
• Age of the rock a fossil is found in, can also be tested.
• Law of Superposition- fossils found deepest in the rock strata are older than the strata at the top. Is useful for following evolution progression
• Study of Fossils is called Paleontology
Law of Superposition
3. Biochemical Evidence
• Chemicals such as Proteins, Amino Acids and Nucleic Acids (DNA and RNA) can be studied to compare organisms.
• examples: chimpanzees and Humans are 96% the same by chemical composition
• Horseshoe Crabs are more related to Arachinids than Crusteaceans.
4. Anatomical Evidence• Vestigial Organs or Structures- have no
apparent use or function.
• May be clues to a distant past
• Examples: wings of flightless birds, pelvic bones in Whales and some Snakes
Vestigial organs continued
• Human Vestigial organs- Appendix, Wisdom and Canine teeth, Male nipples, Human Tailbone and Muscles to move ears
• Homologous Structures- Body parts that differ in use but are similar in structure.
• A Man’s arm and a Whale flipper would be considered Homologous.
• Analogous Structures- Body parts that are different in structure but perform a similar task.
• Ex. Bats wing, Butterfly’s wing and Birds wing are analogous
5. Embryological Evidence
• In early embryos, Organisms that are related develop in a similar way. All vertebrates develop alike until late stages.
• Under this concept, all vertebrates are more closely related to Echinoderms (starfish) than other invertebrates
• See next slide.