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Name __________________________________________

EVIDENCE FOR EVOLUTION A. EVIDENCE FROM STRUCTURE Studying the structures of organisms in order to discover their likenesses and differences is call comparative anatomy. The study of comparative anatomy reveals the basic plan upon which all vertebrates are structured. The variations on this plan appear to be the result of adaptation to environment. Study the illustration below, which show a comparison of the forelimbs of six animals. Use the same letters shown on the human arm to label similar parts on the other animals’ forelimbs. Then fill in the blanks below.

1. The structures are called ________________________________________________________ structures.

2. Each limb has a similar _________________________, but some have different _______________________.

3. The similarity of structure is evidence that the animals ____________________________________________

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B. EVIDENCE FROM EMBRYOLOGY Evolution occurs slowly. In most cases it is not possible to observe evolution in progress. However, evidence of evolution can be found by observing the early stages of development in vertebrates. All vertebrate embryos start out quite similar in appearance. This similarity has led scientists to infer that these organisms are related through a common ancestor. The diagrams below illustrate stages in the embryonic development of a fish, a pig, and a human. Study the diagrams on the next page and then answer the following questions.

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1. How does a comparison of these embryos provide evidence of evolution? ____________________________

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2. Which of the above species would be most biochemically similar to humans – the fish or the pig? Why?

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C. EVIDENCE FROM MOLECULAR BIOLOGY Amino acid sequences of certain proteins can be used to determine how closely related different species are. If the amino acid sequences for a certain protein are very similar in two species, one can assume that those two species had a common ancestor. All 104 amino acids in the protein cytochrome “c” are identical in humans and chimpanzees. The following chart shows how many of the amino acids in cytochrome “c” in other animals differ from those in humans and chimpanzees. Study the cart, and answer the questions that follow.

Animal Number of Amino Acid Differences in Cytochrome C

Dog 8 Dogfish shark 24 Rattlesnake 12 Rhesus monkey 1

1. Explain how this chart supports evolutionary theory. ______________________________________________

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2. Name the animal group to which each of the animals in the chart belongs.

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D. EVIDENCE FROM FOSSILS Fossils are preserved remains of ancient organisms. The age of fossils can be determined by studying the strata, or layers, of rock that are formed over time. The oldest fossils are found in the deepest layers, while the youngest fossils are found closer to the surface. 1. Label the fossil that is the oldest. 2. Label the fossil that is the youngest. 3. Explain how you know the relative age of these fossils:

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