But let us not saddle Sociobiology with the sins of past determinists. What have been its direct results in the first flush of its excellent publicity? At best, we see the beginnings of a line of social research that promises only absurdity by its refusal to consider immediate nongenetic factors. The January 30, 1976, issue of Science (America’s leading technical journal for scientists) contains an article on panhandling that I would have accepted as satire if it had appeared verbatim in the National Lampoon. The authors dispatched “panhandlers” to request dimes from various “targets.” Results are discussed only in the context of kin selection, reciprocal altruism, and the food-sharing habits of chimps and baboons—nothing on current urban realities in America. As one major conclusion, they find that male panhandlers are “far more successful approaching a single female or a pair of females than a male and female together; they were particularly unsuccessful when approaching a single male or two males together.” But not a word about urban fear or the politics of sex—just some statements about chimps and the genetics of altruism (although they finally admit that reciprocal altruism probably does not apply—after all, they argue, what future benefit can one expect from a panhandler).
In the first negative comment on Sociobiology, economist Paul Samuelson (Newsweek, July 7, 1975) urged sociobiologists to tread softly in the zones of race and sex. I see no evidence that his advice is being heeded. In his New York Times Magazine article of October 12, 1975, Wilson writes:
In hunter-gatherer societies, men hunt and women stay at home. This strong bias persists in most [my emphasis] agricultural and industrial societies and, on that ground alone, appears to have a genetic origin.… My own guess is that the genetic bias is intense enough to cause a substantial division of labor even in the most free and most egalitarian of future societies.… Even with identical education and equal access to all professions, men are likely to continue to play a disproportionate role in political life, business and science.
We are both similar to and different from other animals. In different cultural contexts, emphasis upon one side or the other of this fundamental truth plays a useful social role. In Darwin’s day, an assertion of our similarity broke through centuries of harmful superstition. Now we may need to emphasize our difference as flexible animals with a vast range of potential behavior. Our biological nature does not stand in the way of social reform. We are, as Simone de Beauvoir said, “l’être dont l’être est de n’être pas”—the being whose essence lies in having no essence.
33 | So Cleverly Kind an Animal
I N Civilization and Its Discontents, Sigmund Freud examined the agonizing dilemma of human social life. We are by nature selfish and aggressive, yet any successful civilization demands that we suppress our biological inclinations and act altruistically for common good and harmony. Freud argued further that as civilizations become increasingly complex and “modern,” we must renounce more and more of our innate selves. This we do imperfectly, with guilt, pain, and hardship; the price of civilization is individual suffering.
It is impossible to overlook the extent to which civilization is built up upon a renunciation of instinct, how much it presupposes precisely the nonsatisfaction … of powerful instincts. This “cultural frustration” dominates the large field of social relationships between human beings.
Freud’s argument is a particularly forceful variation on a ubiquitous theme in speculations about “human nature.” What we criticize in ourselves, we attribute to our animal past. These are the shackles of our apish ancestry—brutality, aggression, selfishness; in short, general nastiness. What we prize and strive for (with pitifully limited success), we consider as a unique overlay, conceived by our rationality and imposed upon an unwilling body. Our hopes for a better future lie in reason and kindness—the mental transcendence of our biological limitations. “Build thee more stately mansions, O my soul.”
Little more than ancient prejudice supports this common belief. It certainly gains no justification from science—so profound is our ignorance about the biology of human behavior. It arises from such sources as the theology of the human soul and the “dualism” of philosophers who sought separate realms for mind and body. It has roots in an attitude that I attack in several of these essays: our desire to view the history of life as progressive and to place ourselves on top of the heap (with all the prerogatives of domination). We seek a criterion for our uniqueness, settle (naturally) upon our minds, and define the noble results of human consciousness as something intrinsically apart from biology. But why? Why should our nastiness be the baggage of an apish past and our kindness uniquely human? Why should we not seek continuity with other animals for our “noble” traits as well?
One nagging scientific argument does seem to support this ancient prejudice. The essential ingredient of human kindness is altruism—sacrifice of our personal comfort, even our lives in extreme cases, for the benefit of others. Yet, if we accept the Darwinian mechanism of evolution, how can altruism be part of biology? Natural selection dictates that organisms act in their own self-interest. They know nothing of such abstract concepts as “the good of the species.” They “struggle” continuously to increase the representation of their genes at the expense of their fellows. And that, for all its baldness, is all there is to it; we have discovered no higher principle in nature. Individual advantage, Darwin argues, is the only criterion of success in nature. The harmony of life goes no deeper. The balance of nature arises from interaction between competing teams, each trying to win the prize for itself alone, not from the cooperative sharing of limited resources.
How, then, could anything but selfishness ever evolve as a biological trait of behavior? If altruism is the cement of stable societies, then human society must be fundamentally outside nature. There is one way around this dilemma. Can an apparently altruistic act be “selfish” in this Darwinian sense? Can an individual’s sacrifice ever lead to the perpetuation of his own genes? The answer to this seemingly contradictory proposition is “yes.” We owe the resolution of this paradox to the theory of “kin selection” developed in the early 1960s by W. D. Hamilton, a British theoretical biologist. It has been stressed as the cornerstone for a biological theory of society in E. O. Wilson’s Sociobiology. (I criticized the deterministic aspects of Wilson’s speculations on human behavior in the last essay. I also praised his general theory of altruism, and continue this theme now.)
The legacy of brilliant men includes undeveloped foresight. English biologist J. B. S. Haldane probably anticipated every good idea that evolutionary theorists will invent during this century. Haldane, arguing about altruism one evening in a pub, reportedly made some quick calculations on the back of an envelope, and announced: “I will lay down my life for two brothers or eight cousins.” What did Haldane mean by such a cryptic comment? Human chromosomes come in pairs: We receive one set from our mother’s egg; the other from our father’s sperm. Thus, we possess a paternal and a maternal copy of each gene (this is not true among males for genes located on sex chromosomes, since the maternal X chromosome is so much longer—i.e. has so many more genes—than the paternal Y chromosome; most genes on the X chromosome have no corresponding copy on the short Y). Take any human gene. What is the probability that a brother will share the same gene? Suppose that it is on a maternal chromosome (the argument works the same way for paternal chromosomes). Each egg cell contains one chromosome of each pair—that is, one half the mother’s genes. The egg cell that made your brother either had the same chromosome you received or the other member of the pair. The chance that you share your brother’s gene is an even fifty-fifty. Your brother shares half your genes and is, in the Darwinian calculus, the same as half of you.
Suppose, then, that you are walking down the road with three brothers. A monster approaches with clearly murderous intent. Your brothers do not see it. You have only two alternatives: Approach it and give a rousing Bronx cheer, thereby warning your brothers, who hide and escape, and insuring your own demis
e; or hide and watch the monster feast on your three brothers. What, as an accomplished player of the Darwinian game, should you do? The answer must be, step right up and cheer—for you have only yourself to lose, while your three brothers represent one and a half of you. Better that they should live to propagate 150 percent of your genes. Your apparently altruistic act is genetically “selfish,” for it maximizes the contribution of your genes to the next generation.
According to the theory of kin selection, animals evolve behaviors that endanger or sacrifice themselves only if such altruistic acts increase their own genetic potential by benefiting kin. Altruism and the society of kin must go hand in hand; the benefits of kin selection may even propel the evolution of social interaction. While my absurd example of four brothers and a monster is simplistic, the situation becomes much more complex with twelfth cousins, four times removed. Hamilton’s theory does not only belabor the obvious.
Hamilton’s theory has had stunning success in explaining some persistent biological puzzles in the evolution of social behavior in the Hymenoptera—ants, bees, and wasps. Why has true sociality evolved independently at least eleven times in the Hymenoptera and only once among other insects (the termites)? Why are sterile worker castes always female in the Hymenoptera, but both male and female in termites? The answers seem to lie in the workings of kin selection within the unusual genetic system of the Hymenoptera.
Most sexually reproducing animals are diploid; their cells contain two sets of chromosomes—one derived from their mother, the other from their father. Termites, like most insects, are diploid. The social Hymenoptera, on the other hand, are haplodiploid. Females develop from fertilized eggs as normal diploid individuals with maternal and paternal sets of chromosomes. But males develop from unfertilized eggs and possess only the maternal set of chromosomes; they are, in technical parlance, haploid (half the normal number of chromosomes).
In diploid organisms, genetic relationships of sibs and parents are symmetrical: parents share half their genes with their children, and each sib (on average) shares half its genes with any other sib, male or female. But in haplodiploid species, genetic relationships are asymmetrical, permitting kin selection to work in an unusual and potent way. Consider the relationship of a queen ant to her sons and daughters, and the relationship of these daughters to their sisters and brothers:
1.The queen is related by 1/2 to both her sons and daughters; each of her offspring carries 1/2 her chromosomes and, therefore, 1/2 her genes.
2.Sisters are related to their brothers, not by 1/2 as in diploid organisms, but only by 1/4. Take any of a sister’s genes. Chances are 1/2 that it is a paternal gene. If so, she cannot share it with her brother (who has no paternal genes). If it is a maternal gene, then chances are 1/2 that her brother has it as well. Her total relationship with her brother is the average of zero (for paternal genes) and 1/2 (for maternal genes), or 1/4.
3.Sisters are related to their sisters by 3/4. Again, take any gene. If it is paternal, then her sister must share it (since fathers have only one set of chromosomes to pass to all daughters). If it is maternal, then her sister has a fifty-fifty chance of sharing it, as before. Sisters are related by the average of 1 (for paternal genes) and 1/2 (for maternal genes), or 3/4.
These asymmetries seem to provide a simple and elegant explanation for that most altruistic of animal behaviors—the “willingness” of sterile female workers to forego their own reproduction in order to help their mothers raise more sisters. As long as a worker can invest preferentially in her sisters, she will perpetuate more of her genes by helping her mother raise fertile sisters (3/4 relationship) than by raising fertile daughters herself (1/2 relationship). But a male has no inclination toward sterility and labor. He would much rather raise daughters, who share all his genes, than help sisters, who share only 1/2 of them. (I do not mean to attribute conscious will to creatures with such rudimentary brains. I use such phrases as “he would rather” only as a convenient shortcut for “in the course of evolution, males who did not behave this way have been placed at a selective disadvantage and gradually eliminated.”)
My colleagues R. L. Trivers and H. Hare have recently reported the following important discovery in Science (January 23, 1976): they argue that queens and workers should prefer different sex ratios for fertile offspring. The queen favors a 1:1 ratio of males to females since she is equally related (by 1/2) to her sons and daughters. But the workers raise the offspring and can impose their preferences upon the queen by selective nurturing of her eggs. Workers would rather raise fertile sisters (relationship 3/4) than brothers (relationship 1/4). But they must raise some brothers, lest their sisters fail to find mates. So they compromise by favoring sisters to the extent of their stronger relationship to them. Since they are three times more related to sisters than brothers, they should invest three times more energy in raising sisters. Workers invest energy by feeding; the extent of feeding is reflected in the adult weight of fertile offspring. Trivers and Hare therefore measured the ratio of female/-male weight for all fertile offspring taken together in nests of 21 different ant species. The average weight ratio—or investment ratio—is remarkably close to 3:1. This is impressive enough, but the clincher in the argument comes from studies of slave-making ants. Here, the workers are captured members of other species. They have no genetic relationship to the daughters of their imposed queen and should not favor them over the queen’s sons. Sure enough, in these situations, the female/male weight ratio is 1:1—even though it is again 3:1 when workers of the enslaved species are not captured but work, instead, for their own queen.
Kin selection, operating on the peculiar genetics of haplodiploidy, seems to explain the key features of social behavior in ants, bees, and wasps. But what can it do for us? How can it help us understand the contradictory amalgam of impulses toward selfishness and altruism that form our own personalities. I am willing to admit—and this is only my intuition, since we have no facts to constrain us—that it probably resolves Freud’s dilemma of the first paragraph. Our selfish and aggressive urges may have evolved by the Darwinian route of individual advantage, but our altruistic tendencies need not represent a unique overlay imposed by the demands of civilization. These tendencies may have arisen by the same Darwinian route via kin selection. Basic human kindness may be as “animal” as human nastiness.
But here I stop—short of any deterministic speculation that attributes specific behaviors to the possession of specific altruist or opportunist genes. Our genetic makeup permits a wide range of behaviors—from Ebenezer Scrooge before to Ebenezer Scrooge after. I do not believe that the miser hoards through opportunist genes or that the philanthropist gives because nature endowed him with more than the normal complement of altruist genes. Upbringing, culture, class, status, and all the intangibles that we call “free will,” determine how we restrict our behaviors from the wide spectrum—extreme altruism to extreme selfishness—that our genes permit.
As an example of deterministic speculations based on altruism and kin selection, E.O. Wilson has proposed a genetic explanation of homosexuality (New York Times Magazine, October 12, 1975). Since exclusive homosexuals do not bear children, how could a homosexuality gene ever be selected in a Darwinian world? Suppose that our ancestors organized socially as small, competing groups of very close kin. Some groups contained only heterosexual members. Others included homosexuals who functioned as “helpers” in hunting or child rearing: they bore no children but they helped kin to raise their close genetic relatives. If groups with homosexual helpers prevailed in competition over exclusively heterosexual groups, then homosexuality genes would have been maintained by kin selection. There is nothing illogical in this proposal, but it has no facts going for it either. We have identified no homosexuality gene, and we know nothing relevant to this hypothesis about the social organization of our ancestors.
Wilson’s intent is admirable; he attempts to affirm the intrinsic dignity of a common and much maligned sexual behavior
by arguing that it is natural for some people—and adaptive to boot (at least under an ancestral form of social organization). But the strategy is a dangerous one, for it backfires if the genetic speculation is wrong. If you defend a behavior by arguing that people are programmed directly for it, then how do you continue to defend it if your speculation is wrong, for the behavior then becomes unnatural and worthy of condemnation. Better to stick resolutely to a philosophical position on human liberty: what free adults do with each other in their own private lives is their business alone. It need not be vindicated—and must not be condemned—by genetic speculation.
Although I worry long and hard about the deterministic uses of kin selection, I applaud the insight it offers for my favored theme of biological potentiality. For it extends the realm of genetic potential even further by including the capacity for kindness, once viewed as intrinsically unique to human culture. Sigmund Freud argued that the history of our greatest scientific insights has reflected, ironically, a continuous retreat of our species from center stage in the cosmos. Before Copernicus and Newton, we thought we lived at the hub of the universe. Before Darwin, we thought that a benevolent God had created us. Before Freud, we imagined ourselves as rational creatures (surely one of the least modest statements in intellectual history). If kin selection marks another stage in this retreat, it will serve us well by nudging our thinking away from domination and toward a perception of respect and unity with other animals.
Ever Since Darwin: Reflections in Natural History Page 23