Behavioral Genomics: A Step Towards Galton

Galton (1858) admired the details of individual variability. Few psychologists share his insight. Most of us profess faith in the "universals of human nature" and dismiss to error, mutation, and infection the rococo detail variations of individuals. Thus, evolution makes adaptations and some of us note that several strategies can occur in the same scorpion fly or in the same human.

The problem remains that of accepting the notion that we are not all the same. Our strategies and our explanations vary sharply from person to person and to about the same degree that the structures of our brains vary.

There is some hope!

Peter McGuffin, Brien Riley, and Robert Plomin (Science, 2001, 1232-1233) endorse the concept of a "Behavioral Genomics." Neat! They take one more step that distances our actions from our mothering that occurred between birth and first grade. They note: "...first is that nearly all behaviors that have been studied show moderate to high heritability --- usually, to a somewhat greater degree than do many common physical diseases. Second, although environment plays a role, its contribution tends to be of the nonshared type, that is environmental factors make people different from, rather than similar to, their relatives." (This latter is a matter definition. According to Plomin et al. "Behavior Genetics," nonshared environment is defined with reference to its impact of making behavior more variable between people. The contrast is with "shared environment," those features that result in greater similarity in people. Shared environment often contributes 1% of the total variance; nonshared contributes about 45% but also includes error variance. Traditional heritability is often around .50 for many traits.)

The goblin is that environmental features make people different because different people interact differently with what appears (to a 3rd observer) to be the "same" environment. That is, two people can go into a common niche and each person constructs two very different worlds in that niche. "Genes" appear to be the more powerful candidate for leading those choices. Matt Ridley reminds us all that Hamilton commented, "The tabula of human nature was never rasa."

McGuffin, Riley, and Plomin do not go so far as Galton did, but they have started down the same path. Galton investigated individual variation in traits; his heirs still talk about quantitative trait loci and continuous distributions of averaged traits such as hyperactivity, IQ, reading disability, personality, schizophrenia, major depression, autism, and (once more for Fred!) hyperactivity. Bouchard's findings with identical twins and the common sense introspection of us older non twins see the order in developmental trajectories and how similar they become as we age to the trajectories of our parents and grandparents.

It will be a while before we give up on the generalities such as a "Darwinian" medicine or the old notion that environment hammers all of us into uniformity. It will be a while before we appreciate our unfolding self that picks details from our world, hammers out the uncomfortable burrs and thorns, lays insulation against cold or heat, or migrates across a mountain or a desert or a divorce court.

Jim B.

Replies:

Behavioral Genetics (4th Ed) Links & Statistics on Line, by Robert Plomin et al, 03/08/01

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