NURTURE IS NATURAL: REPLY TO AMIN AND THOMPSON AND RUSHTON

Behavior and Philosophy, 2003 by Chisholm, James S

ABSTRACT: Two reviews of Death, Hope and Sex in Vol. 29 of this journal revealed some limitations in their authors' understanding of basic principles of evolutionary ecology and life history theory. Amin and Thompson's review criticized my model of the contingent development of alternative reproductive strategies as (1) being too strong, (2) being too mentalistic, (3) being too reliant on the flawed optimality assumption, (4) committing the Naturalistic Fallacy, and (5) ignoring group selection arguments. I accept only the latter criticism. Rushton's review criticizes me for not writing a book about genes, intelligence, and "race" and massively misunderstands the optimality assumption and role of individual differences in evolutionary theory.

Key words: reproductive strategies, evolution and development, optimality assumption, Naturalistic Fallacy

Humans have been selected to provide offspring with environments that foster survival, growth, development, and ultimate reproduction. It is in our nature to nurture-under the appropriate circumstances, that is. Amin and Thompson's (2001) review of Death, Hope and Sex in this journal shows this understanding, but Rushton's (2001) does not. I will quibble with some of Amin and Thompson's criticisms but concentrate on how their group selection perspective on our naturally contingent predisposition to provide nurturing environments improves the main points I was trying to make. I will then show that Rushton misses these points and argue that his understanding of gene x environment interaction (development) is weak and that he massively misunderstands the importance of individual differences in evolutionary psychology.1

Reply to Amin and Thompson

Flawed Because Too Strong

Amin and Thompson say that my model is "powerfully heuristic" but worry that this power may come "at the expense of a grandiosity verging on the absurd" (2001, p. 86). They are concerned that "Chisholm's hypothesis seems to imply that insecure attachment in childhood is a sufficient condition for irresponsible adult reproductive behavior. Thus, the hypothesis is falsified if there are ANY instances of insecurely attached children who grow up to be responsible adults" (2001, pp. 86-87; original emphases).

I hope I did not give the impression that insecure attachment was a sufficient condition for what Amin and Thompson call "irresponsible adult reproductive behavior." As Amin and Thompson note, existing data "strongly support" the hypothesis that insecure attachment may be one condition leading to "irresponsible adult reproductive behavior." There are indeed exceptions to the general hypothesis that early insecure attachment leads to later "irresponsible" adult sociosexual behavior; other "ancillary principles" do come into play, as I mentioned repeatedly. Stable parents in unstable environments and unstable parents in stable environments seem to account for many counterexamples, as do friends, teachers, therapists, etc. Temperament, which has major genetic influences, also interacts with parental behavior to make children more or less sensitive to early attachment experiences, good or bad, as I mentioned (Chisholm, 1999, pp. 99, 103, 107, 144, 152, 157). Even insecurely attached children are capable of socialization and enculturation. Internal working models are not written in stone, and I do not think I implied that they were. The more modest claim of the Draper-Harpending-Belsky-Steinberg-Chisholm hypothesis is that early insecure attachment is, for good evolutionary biological reasons, a risk factor-but not sufficient for early and/or impulsive sexual and aggressive behavior.

Problems with the Optimality Assumption

Amin and Thompson criticize the optimality assumption on the grounds that "the organism is conceived as optimizing to itself, rather than to the environment, and self optimization would seem to be an odd sort, since the thing optimized and the thing to which it is optimized are one in [sic] the same. . ." (2001, p. 87). The optimality assumption does not conceive of the organism as "optimizing to itself." Selection is what optimizes-not organisms. It cannot be stressed enough: "optimal" means simply the best possible or available solution given existing constraints. Constraints include available energy, nutrients, safety, time, and information. Information comes to the organism during ontogeny from its genotype and its history of interactions with its own environment. Selection does optimize organisms to "themselves" in addition to their environments. After all, it is the whole organism that must do the work of fitness, not just in the context of a particular environment but in the context of all of its molecular, cellular, tissue, and organ systems working together. For example, while a slower metabolism might benefit an animal in the form of energy savings, it might exact a cost in the form of decreased survival due to lower body temperature. The optimality assumption leads to the testable expectation that selection will favor mechanisms for finding the best possible balance between the conflicting ends of metabolic efficiency and survival. The organism is thus optimized "to itself; its increased metabolic efficiency is balanced against its lower body temperature. This is why no adaptation can ever be perfect; all adaptations are compromises between two or more competing selection pressures. The concept of "perfect" has no meaning in nature (or nurture). The optimality assumption may be "difficult to apply in practice," but it is still the best way to ensure that our thinking about evolution accords with the logic of natural selection.