Book: The Agile Gene

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Dead men tell no tales, and if there were any tribes of other type than this they have left no survivors. Our ancestors have bred pugnacity into our bone and marrow, and thousands of years of peace won’t breed it out of us.

William James

Twelve hairy men posed for my imaginary photograph in 1903. Had they met, I doubt that they would have liked each other much. Abrasive Watson, dogmatic Freud, indecisive James, pedantic Pavlov, cocky Galton, dashing Boas—their (innate?) personalities were too disparate, their (acquired?) cultural backgrounds were too diverse, and their whiskers would have gotten tangled.

I suppose it is possible that they could have sorted the mess out at the beginning and avoided a century of dispute about nature and nurture. They could have granted Darwin, James, and Galton the innateness of personality; granted De Vries the particulate nature of inheritance; granted Kraepelin, Freud, and Lorenz a role for early experience in shaping the psyche; granted Piaget the importance of developmental stages; granted Pavlov and Watson the power of learning to reshape the adult mind; granted Boas and Durkheim the autonomous power of culture and society. All these things could be true at the same time, they could have said. Learning could not happen without an innate capacity to learn. Innateness could not be expressed without experience. The truth of each idea is not proof of the falsehood of another.

Possible, but not likely. Even if they had achieved this—for philosophers—a superhuman feat, I cannot see them binding those who followed them to the treaty. Hostilities would have resumed soon enough between the partisans of different theories: it’s in human nature. There seems to be something almost inevitable about dividing human psychology into nature and nurture. Perhaps, as Sarah Hrdy has suggested, the dichotomy is itself an instinct—in the genes. Instead of stately progress toward enlightenment, the twentieth century saw a collision of ideas, a hundred years’ war between the forces of nature and the forces of nurture. Anthropology was its Flanders, Harvard its Manassas, Russia its Russia. Remaining neutral was difficult; those who kept the respect of both sides, such as John Maynard Smith and Pat Bateson, found it hard going. Too many slipped into the false equation that to prove one proposition right was to prove another wrong—that success for nature could only mean defeat for nurture, or vice versa. Even as they repeated the platitude, “Of course, it’s both,” many could not resist the temptation to see the situation in zero-sum terms, like a battle. I hope I have shown in this book how mistaken this is. I hope I have shown that the more we discover genes that influence behavior, the more we find that they work through nurture; and the more we find that animals learn, the more we discover that learning works through genes.

Bizarrely, even the fiercest warriors of the hundred years’ war knew this. The following quotations are all from veterans of those wars. Can you tell which side they were on?

[I view] humans as dynamic, creative organisms for whom the opportunity to learn and to experience new environments amplifies the effect of the genotype on the phenotype.

Each person is molded by an interaction of his environment, especially his cultural environment, with the genes that affect social behavior.

Where on earth did the myth of the inevitability of genetic effects come from?

If my genes don’t like it, they can jump in the lake.

In so far as any aspect of life can be said to be in the “genes,” our genes provide the capacity for both specificity—a lifeline relatively impervious to developmental and environmental buffering—and plasticity—the ability to respond appropriately to unpredictable environmental contingency.

If we are programmed to be what we are, then these traits are ineluctable. We may, at best, channel them, but we cannot change them either by will, education or culture.

An organism’s genes, to the extent that they influence what the organism does, in its behavior, physiology, and morphology, are at the same time helping to construct an environment.

I’m a reductionist and a geneticist. Memory is, in a sense, the sum of all memory genes.

The quotations are, in order, from Thomas Bouchard, Edward Wilson, Richard Dawkins, Steven Pinker, Steven Rose, Stephen Jay Gould, Richard Lewontin, and Tim Tully. The first four would be considered extreme genetic determinists by the second four. Yet, in truth, each of these polemicists believes roughly the same thing: that human nature comes from an interaction of nature with nurture, and that only his opponent holds immoderate views. But his opponent is a straw man.

In the history of the nature–nurture debate, the truly great breakthroughs, the moments of startling enlightenment, are impossible to categorize as victories for either side. The experiments I have celebrated in this book—Lorenz’s goslings, Harlow’s monkeys, Mineka’s toy snakes, Insel’s voles, Zipursky’s flies, Rankin’s worms, Holt’s tadpoles, Blanchard’s brothers, and Moffitt’s children—in each and every case provide evidence of genes that work by reacting to experience.

The Lorenzian gosling is genetically programmed to imprint on whatever the environment provides as a model parent. The Harlovian monkey is genetically inclined to prefer certain kinds of mothers but cannot develop properly without maternal love. The Minekan snake elicits an instinctive phobia, but only if paired with a fearful reaction from a model. The Inselar vole is programmed to fall in love, but only in response to certain experiences. The eyes of the Zipurskian fly are equipped with genes that feel their way into the brain, responding to the environment they find along the way. The Rankinian worms alter the expression of their genes in response to schooling. The Holtian tadpole has growth cones on the tips of its neurons that express genes in response to the world around them. The Blanchardian womb of a mother of many sons is made more likely, through her genes, to cause her next son to be gay. A Moffittian abused child is nurtured to display antisocial behavior, but only if equipped with a certain version of a gene. These are truly the experiments that show genes to be the epitome of sensitivity, the means by which creatures can be flexible, the servants of experience. Nature versus nurture is dead. Long live nature via nurture.

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