Chapter 21: Darwinism and the Evidence for Evolution

1.	The geneticist James Crow wrote that successful scientific theories have the following list of characteristics: * They explain otherwise puzzling observations. * They provide connections between otherwise disparate observations. * They make predictions that can be tested. * They are heuristic, meaning that they open up new avenues of theory and experimentation. Crow added two other elements, which he considered important on a personal, emotional level: * They should be elegant, in the sense of being simple and powerful. * They should have an element of surprise. How well does the theory of evolution by natural selection fulfill these six criteria? Think of a theory you’ve been introduced to in another science course, for example the atomic theory, and evaluate it using this list.   To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.
2.	The average height of humans has increased steadily for the past 100 years in the industrialized nations. This trait has clearly changed over time. Most physicians and human geneticists believe that the change is due to better nutrition and less disease. Has human height evolved?   To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.
3.	Genome sequencing projects may dramatically affect how biologists analyze evolutionary changes in quantitative traits. For example, suppose the genomes of many living humans are sequenced, and that genomes could be sequenced from many people who lived 100 years ago (this might be possible to do using preserved tissue). If 20 genes have been shown to influence height, how could you use the sequence data from these genes to test the hypothesis that human height has evolved in response to natural selection?   To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.
4.	Examine Figure 21.6 on page 421 of your textbook. How would you expect the data on this map to change over the next several decades as drug-resistant strains of M. tuberculosis increase in frequency in North America and Western Europe?   To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.