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.