DEEP ETHOLOGY
EVOLUTION
ADAPTATIONISM
ADAPTATIONISM attempts to frame the existence and persistence of traits as adaptations that arose through natural selection… It
IS SOCIOBIOLOGY ADAPTATIONIST? (is that bad?)
“Sociobiology is one manifestation of the adaptationist program, concentrating on the behavioral aspect of the phenotype” and each of the three elements of sociobiological theory –description, heritability, and adaptive story– “has its own deep methodological problems that have not been faced, or apparently even been considered, by the practitioners of the program when applied to humans” (Lewontin 1979:337).
1. Description. deep errors tinged by historical and ideological assumptions
a. Arbitrary agglomeration. “What are the “natural” suture lines for evolutionary dynamics?” (what are th phenotypic units of evolution?)
b. Reification. “…erroneous confusion of metaphysical categories with real objects.”
Conflation “metaphors . . .carry with them derived, animal significance and become erroneously conflated with the original human concept.”
c. Confusion of levels. “sociobiology attempts to explicate the specific content of human actions as flowing from the genotype which is a quality of individuals. . . .The basic philosophical error is the confusion of properties of sets with properties of members of sets.”
2. Heritability “Knowledge of the relative amounts of genetic variance for different traits is essential if evolutionary arguments are to be correct rather than simply plausible” (p341).
3. Adaptive story. Two methods depending on the degree of specification of the trait.
a. Experimental stories used for “extant species where traits and environment are measurable.
” Progressive ad hoc optimization, in Lewontin’s (1979) term: “an aspect of the organism’s life history is isolated as a problem to be solved.” It is “progressive” because less than optimal solutions begin a cascade of modifications of the definition of the problem or (more usually) proposing additional subordinate problems.
b. Imaginative reconstruction, is Lewontin’s term for “thinking about a species, past or present, and literally inventing a reason why a certain trait should have been favored by natural selection. All of human sociobiological explanation is of this kind,” according to Lewontin (1979:345), “Some such explanations are no doubt correct, but others are not, and in the absence of experimental falsifiability there is no way to tell which is which.”
DEFENSE OF Adaptationism:
But “. . .one point which I think all evolutionists are agreed upon, that it is virtually impossible to do a better job than an organism is doing in its own environment” (Lewontin 1967 cited by Dawkins 1982:30)
“Adaptationism can have virtues as well as faults. . . . Adaptationism as a working hypothesis, almost as a faith, has undoubtedly been the inspiration for some outstanding discoveries. . . . Adaptationist thinking, if not blind conviction, has been a valuable stimulator of testable hypotheses in physiology” (Dawkins 1982:32,31,32)
In The Extended Phenotype, Dawkins (1982 chapter 3) replies to Lewontin and deflects rather than confronts his critique by agreeing with his criticisms but saying they only apply to “naive” adaptationism (“There is, indeed, much more agreement than the polemical tone of recent critiques would suggest.”)
Dawkins iterates 3 trivial (Lewontonian) and 6 significant constraints on perfection which, if kept in mind, will wring profit from otherwise “naive adaptationism”:
Dawkins agrees with Lewontin about the first three, but shows why he regards them as trivial
- neutral mutations. The argument is irrelevant (they have not phenotypic significance.
- allometry. apparently constitutional proportionalities of growth can themselves evolve
- pleiotropy. Lewonton felt that many changes in characters may be the effects of the pleiotropic effects of a gene rather than selection on the character itself. (But Lewontin, according to Dawkins, takes the static view that pleiotropy is a product of the gene rather than of the interaction of the gene with other variables (other genes, environment…))
His own list of constraints admittedly overlaps with several other authors:
- Time lags. Our animal is perpetually out of date: The present traits of extant animals are generally forged when conditions were different (Gannets could rear 2 eggs; moths into the flame…) (the “lag load” of Maynard Smith)
- Historical constraints. The giraffe’s lyrngeal nerve, the flatfish’s retina (adaptive organization in “a patchwork of makeshifts pieced together, as it were, from what was available when opportunity knocked, and accepted in the hindsight, not the foresight, of natural selection” (Pittendrigh 1958 cited by Dawkins 1982)
- Available genetic variation. Natural selection can only act the available genetic variation
Dawkins suggests meliorizing instead of optimizing: that is, animals subject to natural selection attain thereby a melior not an optima –better, not best, situation.
- Constraints of costs and materials. (“If there were no constraints. . .the best phenotype would live forever…” (Maynard Smith quoted by Dawkins 1979). “Any view of biological optimization that denies the existence of costs and trade-offs is doomed” (p47).
- Imperfections at one level due to selection at another level. “… a group selectionist might well see as imperfections, features which an individual selectionist would see as adaptations” (p50). This is why Dawkins thinks it is unfair of Gould & Lewontin (1979) “to equate modern adaptationism with the naive perfectionism that Haldane named after Voltaire’s Dr. Pangloss.”
- Mistakes due to environmental unpredictability. The conditions that an animal is adapted to is a statistical average, the details are expected to vary so apparent mistakes are inevitable, particularly in behavior.
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Adaptationism–how to carry out an exaptationist program. Andrews PW, Gangestad SW, Matthews D. (Department of Psychology, University of New Mexico, Albuquerque, NM 87131, USA.)
Adaptationism is a research strategy that seeks to identify adaptations and the specific selective forces that drove their evolution in past environments. Since the mid-1970s, paleontologist Stephen J. Gould and geneticist Richard Lewontin have been critical of adaptationism, especially as applied toward understanding human behavior and cognition. Perhaps the most prominent criticism they made was that adaptationist explanations were analogous to Rudyard Kipling’s Just So Stories (outlandish explanations for questions such as how the elephant got its trunk). Since storytelling (through the generation of hypotheses and the making of inferences) is an inherent part of science, the criticism refers to the acceptance of stories without sufficient empirical evidence. In particular, Gould, Lewontin, and their colleagues argue that adaptationists often use inappropriate evidentiary standards for identifying adaptations and their functions, and that they often fail to consider alternative hypotheses to adaptation. Playing prominently in both of these criticisms are the concepts of constraint, spandrel, and exaptation. In this article we discuss the standards of evidence that could be used to identify adaptations and when and how they may be appropriately used. Moreover, building an empirical case that certain features of a trait are best explained by exaptation, spandrel, or constraint requires demonstrating that the trait’s features cannot be better accounted for by adaptationist hypotheses. Thus, we argue that the testing of alternatives requires the consideration, testing, and systematic rejection of adaptationist hypotheses. Where possible, we illustrate our points with examples taken from human behavior and cognition.
example of exaptation:
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REFERENCES
Dawkins, R. 1982. The Extended Phenotype. Oxford University press
Gould, Stephen Jay and Richard C. Lewontin, 1979. The spandrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptationist Programme. Proc. Roy. Soc. Lond., B. Biol. Sci.. 205:581-598. (17pp)
Lewontin, R.C. 1979. Sociobiology as an adaptationist program. Behavioral Science 24(1); reprinted in Biology and the Social Sciences: An Emerging Revolution ed by Th. C. Wiegele (1982), Westview Press, Boulder CO.
Mayr, Ernst. 1983 How to carry out the adaptationist program? The American Naturalist 121(3):324-334 (10pp) |
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April 2003