MONDAY, SEPTEMBER 13, 1999 Reading Assignment: Why We Get Sick: The New Science of Darwinian Medicine, pp. 13-25. CHAPTER 2: EVOLUTION BY NATURAL SELECTION: How do Nesse & Williams explain the process of natural selection? Does the British moth example illustrate natural selection? Does Herbert Spencer's catchy phrase "survival of the fittest" capture the essence of evolution by natural selection? If not, what misunderstandings does it promote? NATURAL SELECTION BENEFITS GENES, NOT GROUPS: Is group selection exemplified by lemmings engaging in mass suicide when food is scarce? Can group selection ever occur? How does Richard Dawkins's characterization of organisms as vehicles created by genes in order to replicate themselves fit in with ideas that evolution tends toward a world of health, harmony, stability, and happiness? How apt is Dawkins's moniker "selfish genes"? KIN SELECTION: Does reproduction by a carrier organism enable a gene to get more copies of itself into future generations? Always? Suppose that the carrier organism performs actions that increase the reproductive success of its close relatives. Does this circumstance also enable a gene to get more copies of itself into future generations? Why is it called "kin selection"? Explain J.B.S. Haldane's quip that he'd sacrifice his life for two brothers or eight first cousins, but not for one brother or seven cousins? Is kin selection the only exception to the "Nice-guys-finish-last" principle (formulated by Leo Durocher, manager of the old Brooklyn Dodgers)? What is reciprocity? Does reciprocity amount to mutual backscratching? Explain how reciprocal behavior by the carrier organism enables a gene to get more copies of itself into future generations. What bearing do kin selection and reciprocity have on social behavior and the possibility of altruism? HOW DOES NATURAL SELECTION OPERATE? Does natural selection proceed according to some overall plan or scheme? In some particular direction, e.g., toward better or higher beings? Is it predictable? If not, is the theory of natural selection untestable? In what five ways does chance influence natural selection? If one rewound and then replayed the tape of biological history, would one see the same show? Would there be humans in the replay? Does natural selection always do what is best for the long-term welfare of a species? Does it create every adaptation that would be valuable to a species? Explain how natural selection approaches perfection by optimizing certain quantitative features of organisms? Give some animal and human examples. What is the point of the yarn about Henry Ford and the steering column of his Model T's? What's the connection between costs and benefits? Does natural selection ever compromise, i.e., does it ever make decisions based on cost-benefit analyses? Give some animal and human examples. Are some apparent design mistakes really positive benefits to an organism? Give examples? TESTING EVOLUTIONARY HYPOTHESES: Aristotle, the father of functional analysis (What is it for?), stated that the body as a whole has a special purpose or function. What do Nesse & Williams take that purpose or function to be? What does it mean to say that a biological trait or behavior is "adaptive"? Give animal and human examples. Can one test hypotheses about the adaptiveness of traits or behaviors? Mention some adaptational hypotheses that are superficially attractive but empirically false. Mention some adaptation hypotheses that are obviously true. Which adaptational hypotheses do Nesse & Williams view as "interesting"? THE ADAPTATIONIST PROGRAM: What is the method of inquiry that has been called "the adaptationist program"? Does it ever lead to novel predictions? To empirically testable knowledge? Explain the significance of Nesse & Williams three examples: How beavers decide which trees to fell; How woodland songbirds decide how many eggs to lay; and How woodland songbirds determine the male-female ratio of their offspring. How do adaptationists explain the 50-50 sex ratio of humans and other sexual animals? What does it have to do with the genetic fact that an individual has an equal chance of getting an X or a Y chromosome from its father? What bearing do Nesse & Williams think the adaptationist program has for the investigation of disease, illness, and physiological disorders? Do they expect it to lead to important medical discoveries? Can a trait or behavior have more than one function or purpose? Give animal and human examples. What experimental limitations does the adaptationist program encounter? If we cannot reconstruct the history of a trait or behavior, how can we be confident that it was shaped by natural selection? How many of the evolutionary (adaptationist) hypotheses advanced in their book do Nesse & Williams consider to be tested and confirmed? What is their goal or objective?