Shadows of Forgotten Ancestors

If the predator’s eye/retina/brain combination is geared especially to detect motion, the prey often have, in their repertoire of defenses, the tactic of standing frozen, stock-still, for long periods of time. It’s not that squirrels, say, or deer understand the physiology of their enemies’ visual systems; but a beautiful resonance between the strategies of predator and prey has been established by natural selection. The prey animal may run; play dead; exaggerate its size; erect its hairs and shout; produce foul-smelling or acrid excretions; threaten to counterattack; or try a variety of other, useful survival strategies—all without conscious thought. Only then may it notice an escape route or otherwise bring into play whatever mental agility it possesses. There are two nearly simultaneous responses: one, the ancient, all-purpose, tried-and-true, but limited and unsubtle hereditary repertoire; and the other, the brand-new, generally untried intellectual apparatus—which can, however, devise wholly unprecedented solutions to urgent current problems. But large brains are new. When “the heart” counsels one action and “the head” another, most organisms opt for heart. The ones with the biggest brains more often opt for head. In either case, there are no guarantees.

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Obliged to accommodate to every twist and turn in the environment they depend upon, living things evolve to keep up. By painstaking, small steps, through the passage of immense vistas of geological time, via the deaths of innumerable slightly maladapted organisms, uncomplaining and unlamented, life—in its interior chemistry, external form, and menu of available behavior—became increasingly complex and capable. These changes, of course, are reflected in (indeed, caused by) a corresponding elaboration and sophistication of the messages written in the ACGT code, down there at the level of the gene. When some splendid new invention comes along—bony cartilage as body armor, say, or the ability to breathe oxygen—the genetic messages responsible proliferate across the biological landscape as the generations pass. At first no one has these particular sequences of genetic instructions. Later, large numbers of beings all over the Earth live by them.

It’s not hard to imagine that what’s really going on is an evolution of genetic instructions, battles between the genetic instructions of competing organisms, genetic instructions calling the shots—with the plants and animals little more, or maybe nothing more, than automata. The genes arrange for their own continuance. As always, the “arranging” is done with no forethought; it’s merely that those beautifully coordinated genetic instructions that, by chance, give superior orders to the living thing they inhabit make more living things motivated by the same instructions.

Think again of the changes in our behavior caused by the incursion of a rabies or an influenza virus (made of nucleic acids wearing a coat of protein). Surely much more profound control over us is exercised by our own nucleic acids. When you strip away the fur and feathers, the physiological and behavioral particularities, life is revealed to be the preferential replication of some ACGT messages rather than other, competing messages; a conflict of genetic recipes; a war of words.

In this perspective,¹¹ it’s the genetic instructions that are being selected and that are evolving. Or you might with nearly equal justice say it’s the individual organisms, under the tight control of the genetic instructions, that are being selected and that are evolving. There is no room here for group selection—the natural and attractive idea that species are in competition with one another, and that individual organisms work together to preserve their species as citizens work together to preserve their nation. Acts of apparent altruism are instead attributed chiefly to kin selection. The mother bird slowly flutters from the fox, one wing bent as if broken, in order to lead the predator away from her brood. She may lose her life, but multiple copies of very similar genetic instructions will survive in the DNA of her chicks. A cost-benefit analysis has been made. The genes dictate to the outer world of flesh and blood with wholly selfish motives, and real altruism—self-sacrifice for a non-relative—is deemed a sentimental illusion.¹²

This, or something quite like it, has become the prevailing wisdom in the field of animal (and plant) behavior. It has considerable explanatory power. At the human level it helps to explain such varied matters as nepotism and the fact that foster children are much more likely (in America, for example, about a hundred times more likely¹³) to be fatally abused than children living with their natural parents.