WEDNESDAY, SEPTEMBER 8, 1999 Reading Assignment: Why We Get Sick: The New Science of Darwinian Medicine, pp. ix-12. Preface, pp. ix-xi.

Who are the two authors? Why was Randolph Nesse frustrated in psychiatry? What significance did Nesse see in George Williams's evolutionary explanation of aging? In Paul Ewald s evolutionary treatment of infectious disease? How is the present book related to Nesse & Williams s 1991 joint article The Dawn of Darwinian Medicine ? Do Nesse & Williams think that Darwinian Medicine is a miscellany of unrelated ideas or a coherent new field? Does Darwinian Medicine promote health? Are their examples meant to be medical advice or authoritative analyses? Do Nesse & Williams reject conventional Western medicine? How are Darwinian and Western medicine related? Chapter 1: The Mystery of Disease, pp. 3-12. What is the baffling paradox with which the chapter opens? What diseases do we know a lot about why particular people get them, but fail altogether to understand why they occur at all? Give some examples. Formulate what Nesse & Williams call the great mystery of medicine. What bearing does it have on the theistic Argument from Design? Can an evolutionary approach help solve this mystery? Piecemeal or wholesale? Doesn t natural selection tend to produce organisms well adapted to their environments? Isn t it at least prima facie paradoxical, therefore, that natural selection hasn t eliminated the genes that make us susceptible to these diseases, especially when the diseases are very old? How well designed are our bones? Kidneys? Heart valves? Brains? Hormonal system? Sensorimotor system? How well designed is the crossover of the trachea and the esophagus? Our optical lenses? Our arteries? Our immune system? The course of pregnancy? The aging process? Our food cravings? Male ?female sexuality? Our anxiety mechanism? Two Kinds of Causes (pp 6-7): How do evolutionary causes differ from proximate causes? How are they related? What do proximate explanations do? Evolutionary explanations? What kinds of questions does each type of explanation try to answer. Illustrate the difference between them by sketching explanations of the external ear and of taste buds. With which kind of explanation does Western medicine largely concern itself? Is physiology concerned with function and purpose? Biochemistry? Are these disciplines part of Darwinian medicine? Is Darwinian medicine mostly speculative? How does Margie Profet explain morning sickness? Is this a Darwinian account? Can evolutionary explanations make predictions about proximate mechanisms? Illustrate your answer by invoking the low iron levels found in patients with infections? Is this a case where Darwinian medicine makes a therapeutic recommendation? The Causes of Disease (pp. 8-11): Nesse & Williams propose the following six categories of evolutionary explanation as their formal framework for Darwinian medicine. Do they really constitute a formal framework for Darwinian medicine? 1. Defenses: Distinguish defects from defenses. Illustrate the distinction by invoking the signs of pneumonia. Is eliminating a defect usually a good idea? Ditto for defenses? 2. Infection: In what sense are bacteria and viruses sophisticated opponents? To what arms race are Nesse &Williams alluding? 3. Novel Environments: For what kind of environment(s) was our bodies shaped by natural selection? What bearing does environmental mismatch have on disease and epidemics? 4. Genes: Why are some genes perpetuated despite the fact that they cause disease? In your response, bring in genes with harmless quirks versus those with positive benefits. Are defective genes that result from mutation a serious health problem? What are outlaw genes? Do they pose a serious health problem? 5. Design Compromises: Are design flaws always mistakes or sometimes compromises? If the latter, do they have benefits, even if hidden? Give examples. 6. Evolutionary Legacies: Is evolution incremental or saltational? How does history constrain or encumber designers, natural selection included? What We Are Not Saying (pp. 11-12): Explain the connection between Darwinian medicine, eugenics, and Social Darwinism. How Darwinian is/was Social Darwinism? Does Darwinian medicine hold that disease, or at least some diseases, is good? What are the moral implications of Darwinian evolution? (To be continued)
 
 

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?
 
 

PHIL 1800: MISCELLANEOUS ITEMS 1 Conwy Lloyd Morgan (1852-1936): Influential British psychologist, Professor and later Vice- Chancellor of the U. of Bristol, careful experimenter in animal learning, and a principal founder of comparative psychology. Much of the technical vocabulary of contemporary animal science comes from Lloyd Morgan, e.g., 'trial-and-error learning', 'reinforcement', and 'inhibition.' In his 1894 book, Introduction to Comparative Psychology, Lloyd Morgan enunciated his celebrated and influential methodological canon, to wit: MORGAN'S CANON: "In no case may we interpret an action as the outcome of the exercise of a higher psychical faculty, if it can be interpreted as the outcome of one which stands lower in the psychological scale." Chagrined that scientists were (mis)using his canon to rule out all attributions to animals of higher mental faculties, Lloyd Morgan added the following rider in his 1900 book, Animal Behavior: RIDER TO MORGAN'S CANON: "To this [Morgan's canon] it may be added -- lest the range of the principle be misunderstood -- that the canon by no means excludes the interpretation of a particular act as the outcome of the higher mental processes if we already have independent evidence of their occurrence in the agent." THINGS TO THINK ABOUT: (1) How does Morgan's canon apply to the case of Clever Hans? (2) Morgan's canon presupposes an ordering, from lower to higher, of psychical or mental faculties. Does there exist objective ordering(s) of this sort, i.e., ones that are not biassed or culturally determined or whimsical? What was Lloyd Morgan's own view of this matter? (3) Does Morgan's canon really do what Lloyd Morgan wanted it to do, viz., to prevent scientists from using his canon to deny higher mental processes to animals when the evidence strongly supported such an attribution? ON DECEPTION BY ANIMALS: (1) What is meant by 'theory of mind' in cognitive ethology and comparative psychology? (2) Massey claims that any episode of apparent bonafide deception by animals can always be interpreted as the result of the animal following low-level procedural rules, i.e., without crediting the 'deceiving' animal with theory of mind. Evaluate this claim. (3) What is the intellectual or scientific cost of interpreting episodes of apparent deception by animals as the result of the animal's following procedural rules? [Hints: What additional hypotheses are needed to make the low-level interpretation go through? If the probabilities of events E1,...,En are P1,...,Pn and if these probabilities are independent of each other, what is the probability of the sequence of events ?] (4) What is the intellectual or scientific cost of interpreting an episode of apparent deception by animals as bonafide or genuine deception? (5) What's the difference between local and global simplicity? Give examples. How do these two simplicity concepts apply to animal deception?

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? "The process is fundamentally very simple: natural selection occurs whenever genetically influenced variation among individuals affects their survival and reproduction. If a gene codes for characteristics that result in fewer viable offspring in future generations, that gene is gradually eliminated. For instance, genetic mutations that increase vulnerability to infection, or cause foolish risk taking or lack of interest in sex, will never become common. On the other hand, genes that cause resistance to infection, appropriate risk taking, and success in choosing fertile mates are likely to spread in the gene pool, even if they have substantial costs." (My italics) Does the British moth example illustrate natural selection? Yes, the rare mutant form of moth (its darker color better matched color of pollution-coated trees, making it harder for birds to detect them) spread quickly. 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? Not at all. Survival is of no consequence per se, e.g., consider salmon and annual plants that reproduce once and then die. Survival increases fitness only so far as it increases reproduction. 'Fittest' does not mean healthiest, strongest, fastest, etc. Roughly, those with the most grandchildren are the fittest. Fitness is not absolute but is relative to environments. Even in a particular environment, every gene involves compromises, e.g., fearfulness in rabbits. NATURAL SELECTION BENEFITS GENES, NOT GROUPS: Is group selection exemplified by lemmings engaging in mass suicide when food is scarce? No, this is a hokey example cooked up by a TV company. Lemmings seldom drown or fall victim to mass accidental death en masse. Consider two imaginary lemmings, one with self-sacrificial genes, the other without them. Which one would likely have the most grandchildren? Can group selection ever occur? Yes, but only under very special and rare circumstances. 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"? It shows how misguided these ideas are. What promotes reproductive success will be selected for, irrespective of how it affects individuals. Dawkins's term nicely emphasizes that genes have no concern for their vehicles as such, but it causes many people to attribute intentionality to genes. KIN SELECTION: Does reproduction by a carrier organism or vehicle enable a gene to get more copies of itself into future generations? Always? Usually, but it depends on the environment, on historical accident, etc. 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? Probably yes, because a child shares all of its genes with an identical twin; [3/4 of its genes with a half-identical twin] 1/2 with a sibling; 1/2 with a parent; 1/4 with a grandparent; and 1/8 with a cousin. From the perspective of your genes, your brother's survival is half as important as yours, etc. 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? Because it is kin with whom we share a significant fraction of genes. Two brothers have same significance for a person's genes as does the person himself, etc. Is kin selection the only exception to the "Nice-guys-finish-last" principle (formulated by Leo Durocher, manager of the old Brooklyn Dodgers)? No, there is also reciprocal exchanges or reciprocity. 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? Reciprocity is mutual favor-granting, positive tit for tat, mutual backscratching. It helps an individual to survive to reproduce and to promote the well-being of offspring. It enables biologists/ethologists to account for altruism, which would otherwise be baffling from an evolutionary point of view. 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? No, no goal or plan apart from fostering reproductive success. Is it predictable? If not, is the theory of natural selection untestable? Although the course of natural selection is not generally predictable, natural selection leads to many predictions, and so is empirically testable. In what five ways does chance influence natural selection? (1) In the production of a genetic mutation; (2) in whether the bearer lives long enough to show the effects of such a mutation; (3) in chance events that influence the bearer's reproductive success; (4) in whether a gene happens to be eliminated by accident; and (5) in unpredictable changes in the environment of the group of organisms that the bearer is a member of. If one rewound and then replayed the tape of biological history, would one see the same show? Would there be humans in the replay? The probability of seeing the same show is zero. Similarly for humans. 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? Natural selection would do what is best for the long-term welfare of a species only if it operated at the group level, which it almost never does. Nor does natural selection create every adaptation that would be valuable to a species, as is shown by African monkeys who lack tails, which their South American counterparts find quite valuable. Explain how natural selection approaches perfection by optimizing certain quantitative features of organisms? Give some animal and human examples. If a quantitative trait serves a definite function, selection among minor modifications results over many generations in an optimal, or nearly optimal, value of the trait. Examples: the length of a birds' wings is long enough to provide good lift but short enough for the bird to maintain control; our blood pressure is optimal, neither too high nor too low. What is the point of the story about Henry Ford and the steering column of his Model T's? What's the connection between costs and benefits? Henry Ford recognized that engineering decisions are based on cost-benefit analyses. A steering column that never breaks down probably has an inordinately high cost. By modestly disimproving the steering column, the engineer could save the Ford company a lot of money without significantly disimproving the hypothetical Model T. Does natural selection ever compromise, i.e., does it ever make decisions based on cost-benefit analyses? Give some animal and human examples. Virtually all the 'decisions" made by natural selection are compromises. Example: the fear instinct of horses is strong enough to enable them almost always to escape predators, but not so strong as to make their lives impossible. Are some apparent design mistakes really positive benefits to an organism? Give examples? A classic example is the gene for sickle cell anemia, which protects against malaria. Another example: our fondness for fat promotes survival in a central-African hunter-gatherer environment. 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? Reproduction! 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? It is adaptive if it promotes reproductive success. E.g., ears enable humans and animals to detect the approach of predators, to communicate over distances, etc., all of which enable the individual to reproduce and get its genes into the next couple of generations. Mention some adaptational hypotheses that are superficially attractive but empirically false. Mention some adaptation hypotheses that are obviously true. False hypotheses: infants cry to exercise their lungs; people die by age 100 to make room for new people. True hypotheses: the heart pumps blood to nourish the cells of the body; coughing expels foreign matter from the respiratory tract; shivering increases body heat. Which adaptational hypotheses do Nesse & Williams view as "interesting"? Ones that are plausible and important, but that are not obviously right or wrong. THE ADAPTATIONIST PROGRAM: What is the method of inquiry known as "the adaptationist program"? Make an educated guess at the functional significance of some known trait or behavior (a functional hypothesis); then form a testable prediction by tracing the consequences of that hypothesis; then test the prediction. If it holds good, we may be on to something; if it proves false, then discard the functional hypothesis. Does it ever lead to novel predictions? To empirically testable knowledge? Yes to both. The three following cases are examples of empirically testable predictions made from functional hypotheses that lead to new knowledge. Explain the significance of Nesse & Williams three examples: (1)How beavers decide which trees to fell; (2) How woodland songbirds decide how many eggs to lay; and (3) How woodland songbirds determine the male-female ratio of their offspring. Gary Belovsky conjectured that beavers decide which trees to cut down in a way that promotes fitness, i.e., in an economically rational way. This functional hypothesis lead to the prediction that the caliper of trees harvested by beavers decreases with distance from their pond, and that at some definite distance only ideal trees would be cut down, and beyond that distance, no trees would be felled. 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? The minority sex has the advantage in mating, so natural selection over time would produce a 50-50 sex ratio. The chromosomal facts are the proximate mechanism by which the result of natural selection is accomplished. 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? They expect it to lead to important medical discoveries, just as it has led to important discoveries in ethology. Can a trait or behavior have more than one function or purpose? Give animal and human examples. Yes, e.g., the tongue plays a role in speech and in eating. What experimental limitations does the adaptationist program encounter? There is no way to experiment on the hypothesized evolutionary history of an organism. If we cannot reconstruct the history of a trait or behavior, how can we be confident that it was shaped by natural selection? Fossils, carbon traces, behavioral tendencies, protein and DNA structures, etc., all help us to reconstruct evolutionary history. Comparative physiology can help to determine the function of a trait or behavior. 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? They claim confirmation for none of them. They want to demonstrate that evolutionary questions are interesting, important, and testable. They hope to cause people to ask new questions.

Descartes's two tests for mind (and especially for animal mind) (From Descartes's Discourse on Method, Part V.) Intuitive uncritical formulation of the Language Test: "The first [of these two very certain means of recognizing that God-made humanlike machines are not true humans] is that they could never use words or other signs, composing them as we do in order to declare our thoughts to others. Critical formulation of the Language Test: "For one can readily conceive that a machine might be made in such a way that it produces words, and even that it produces some words relevant to the corporeal actions that effect some change in its organs, e.g., that if one touches it in a certain place, it will ask what one wishes to say to it; and that if one touches it in another place, it will exclaim that one is hurting it, and the like. But one cannot conceive that the machine could arrange words so diversely as to respond to the meaning of all that might be said in its presence, as even the most stupid human beings can do." (AT VI, 56; Massey's translation; translator's insertions are always in brackets). [That is to say, the test consists in determining whether the subject can furnish an appropriate verbal response to anything that might be said in its presence.] Original French text of critical version of Language Test: Car on peut bien concevoir qu'une machine soit tellement faite qu'elle profere des paroles, ?mesme qu'elle en profere quelques unes a propos des actions corporelles qui causeront quelque changement en ses organes: comme, si on la touche en quelque endroit, qu'elle demande ce qu'on lui veut dire; si en un autre, qu'elle crie qu'on lui fait mal, ?choses semblables; mais non pas qu'elle les arrenge diversement, pour repondre au sens de tout ce qui se dira en sa presence, ainsi que les hommes les plus hebetez peuvent faire. (AT VI, 56-57; diacritical marks omitted.) First version of the Action Test: "And the second [very certain means of recognizing that God-made humanlike machines are not true humans] is this. Although such machines might do a number of things as well as or perhaps better than any of us, they would inevitably flounder ineffectually in some others. By these ineffectual flounderings one would discover that they do not act through understanding but solely through the disposition of their organs. For whereas reason is a universal instrument which is of service in all situations, these organs need a particular disposition for each particular action. From this it follows that it is morally impossible that there be enough diversity of organs and dispositions in a machine to make it act in all life situations in the same way that our reason causes us to act." Critical version of Action Test: "It is also a very remarkable thing that, although there are a number of animals that manifest more practical intelligence in some of their actions than we do, one nonetheless observes that in many other actions these same animals manifest no practical intelligence at all, so that what they do better than us does not prove that they partake of mind; for, on this score, they would partake more of mind than any of us does, and so would do better at everything. It proves, rather, that they don't partake of mind at all, but that it is Nature which acts in them according to the disposition of their organs. Similarly, people recognize that a clock, which is composed only of wheels and springs, can count the hours and measure time more exactly than we can with all our practical wisdom." (AT VI, 58-59; Massey's translation) French text of critical version of Action Test: C'est aussi une chose fort remarquable que, bien qu'il y ait plusieurs animaux qui tesmoignent plus d'industrie [key word "industrie" can mean something like practical intelligence] que nous en quelques unes de leurs actions, on voit toutefois que les mesmes n'en tesmoignent point du tout en beaucoup d'autres: de facon que ce qu'ils font mieux que nous, ne prouve pas qu'ils ont de l'esprit; car, a ce conte, ils en avroient plus qu'aucun de nous, ?feroient mieux en toute chose; mais plutost qu'ils n'en ont point, ?que c'est la Nature qui agist en eux, selon las disposition de leurs organes: ainsi qu'on voit qu'un horologue, qui n'est compose que de roues; ?de ressors, peut conter les heures, ?mesurer le tems, plus iustement que nous avec toute nostre prudence. (AT VI, 58-59; diacritical marks omitted.)