In the Origin of Species (1859), Charles Darwin argued that the main mechanism of evolutionary change is a process he called natural selection. More organisms are born than can survive and reproduce, bringing on a struggle for existence. Given naturally occurring variation, there will be a differential reproduction—some reproduce, some do not—akin to the artificial selection practiced by animal and plant breeders, with the end result of permanent change. In a drought, animals able to do with less water are "fitter" than those that need to drink more. Moreover, organisms will be adapted: they will show the organic contrivances highlighted by those natural theologians intent on showing that there is a designing God. Examples include the hand and the eye and such like. Darwin applied this mechanism to many different fields of biology, including paleontology, embryology, systematics, and biogeography. Behavior was included in Darwin's theory, for he saw that what an organism does is as crucial in the struggle for existence as what an organism is. There is little point in having the physique of Tarzan if you have the mind of a monk.

The evolution of sociobiology

Darwin was particularly fascinated by certain social behavior, especially that of ants, bees, and wasps (hymenoptera), where an organism sacrifices itself for the good of the group. It seems prima facie that such behavior is at odds with the kinds of self-centered acts that would lead to individual success in the struggle for existence. Darwin understood how the sterility of a worker ant, for example, might be transmitted through fertile nest members—the domestic world had shown how one can select vicariously, as it were, for characteristics in animals that will not themselves breed—but he could not see how sterility itself would come into being. Darwin was convinced that all selection must be for the individual, not the group; sociality—worker sterility, in particular—was a major challenge. Although Darwin concluded that one can regard the colony (of ants and so forth) as a kind of superorganism on which selection can operate as a whole, he never really resolved the problem of sociality.

For a number of reasons, the study of the evolution of social behavior lagged after Darwin. First, the rise of the social sciences with their interests in behavior discouraged biologists from addressing the subject. Social scientists tended to experiment on rats and mice, to generalize, and then to conclude that transpecific differences were irrelevant. Social scientists also tended to work in artificial situations and so were generally not interested in natural behavior, and unable to recognize it when it appeared. Second, in the first half of the twentieth century, the racial doctrines of the Third Reich convinced many that the study of social behavior from a biological perspective would lead to claims about the innate behaviors of humans, with consequent belittling of the worth of those not in one's own group. Although some protested that such fears should not tar all biological studies on behavior, the damage was done and remained for many years after the Second World War. Most importantly, no one really knew how to move theoretically beyond Darwin so that social scientists could study social behavior while staying true to the principles of natural selection. The social sciences needed new approaches that eschewed group selection, allowing evolutionists to dissect nature and drag forth its secrets.

Kin selection. Breakthroughs came in the 1960s. A number of models were devised that allowed scientists to study social behavior in animals, while staying true to the individualist or "selfish" nature of selection. Notable was the theory of kin selection, devised by the English biologist William Hamilton, who showed that close relatives have a biological interest in helping each other because by doing so they indirectly support the success of their own units of heredity, their own genes. Hamilton applied this thinking to the ants, bees, and wasps, pointing out that these animals have a peculiar breeding system, where only females have fathers (males being born from unfertilized eggs). This means that sisters are more closely related to each other than normal. In the usual case (e.g., humans), mothers and daughters are 50 percent related, as are sisters. In the hymenopteran case, a female gets the same genetic input as her sister from their shared father and then 50 percent input from their shared mother. Thus sisters are 50 percent and one-half 50 percent (75%) related, whereas mothers and daughters are just 50 percent related. It is in a worker's reproductive interests to raise fertile sisters rather than fertile daughters—an activity that is aided rather than hindered by the worker's own sterility. There is no need to treat the colony as but one unit for one can see individual interests being played out in this, the most integrated and harmonious of social situation.

Reciprocal altruism. Other models were devised, including one that Darwin himself sensed, even if he did not fully articulate it. Reciprocal altruism works on the principle that when an organism gives help, it is entitled to receive help when needed. Reciprocal altruism can work even among non-relatives, or—at the extreme—across species. Certain fish are major predators, but they tolerate other types of fish that swim directly into their mouths and pick out harmful bacteria and fungi on their gums. The predators practice dental hygiene and the cleaners get a good meal because the larger fish does not swallow the smaller fish in its mouth. Everyone benefits.

Evolutionary equilibrium. Evolutionists turned to game theory in cases where participants adopt various strategies to succeed in the light of the fact that other players (in biological terms, other members of the species) are also trying to succeed. In The Selfish Gene (1976), a provocative popularization of this theory, British biologist Richard Dawkins showed how certain evolutionary situations achieve equilibrium, or reveal what he called "Evolutionary Stable Strategies," when no one member of the group can achieve more than limited benefits, given the conflicting interests of the group. To take one of Dawkins's examples, consider a group with two kinds of members. Some members of the group are "hawks," who in any potential conflict situation are aggressive and will fight if need be. Others in the group are "doves," who always run if a fight looms. One might assume that the hawks would dominate and that selection would produce a population without any doves. But this is not so. A hawk's encounter with another hawk always leads to a fight, which may end with one hawk injured or dead. Doves, however, never get beaten up because they run. So, on average, there is a cost to being a hawk. But doves cannot dominate either, because, on average, there is a cost to being a dove. Hawks always win confrontations between a hawk and a dove. The birds of the group therefore end up in a balanced if uncomfortable midpoint, with neither hawks nor doves able to increase their representation at the expense of the other.

Armed with these theories, naturalists and experimentalists turned to the larger world to determine if they could understand the social behavior not just of insects and fish, but of more complex animals like birds and mammals. The widest range of topics was covered. Notable was a study (led by Cambridge biologist Tim Clutton Brock) of red deer on an island off the coast of Scotland that showed how male deers strive to capture harems and will compete (or not) as it proves to be in their interest, and how female deers, which seem to be controlled by males, will in turn employ tricks and strategies to improve their reproductive options and results. A female wants her offspring, particularly her sons, sired by a male who will pas on his superior breeding qualities. Another study (conducted by Cambridge biologist Nicholas Davies) looked at the dunnocks (hedge sparrows), a bird that has the widest of breeding patterns—monogamy, polygyny (one male, several females), polyandry (one female, several males), and something primly referred to as polyandryny (group sex, with several males and several females). By doing DNA fingerprinting on the birds and their offspring, researchers could trace relationships, demonstrating just how much behavior was controlled by reproductive interests. This study revealed that dunnocks do not raise chicks with whom they have little reason to think they have real blood ties. Moreover, a dominant male (an "alpha") will tend to spend more time chick rearing and to have more offspring than a lesser male (a "beta"). Another study in Holland (reported by ethologist Franz de Waal) looked at relationships within a troop of chimpanzees—how males needed female help to dominate a situation, and how different alliances would be formed according to different interests. Two weaker males might prefer to gang up to defeat a stronger male, rather than simply acting individually.

Edward O. Wilson. Research went ahead with speed and enthusiasm, and before long, the science of the evolution of social behavior—now called sociobiology—was ready to take its proper place in the Darwinian family, along with paleontology and the other subjects. But controversy loomed. Darwin had wanted to apply his ideas to humans, and in the The Descent of Man (1874) he did just that, as did Darwinian scientists who came later, in particular, Harvard entomologist Edward O. Wilson. In a major overview of the field, Sociobiology: The New Synthesis (1975), and later in a work addressing the human species, On Human Nature (1978 ),Wilson argued that nearly every aspect of human life and nature is a function of biology, or, more accurately, the genes as fashioned by natural selection. Sexual differences, family structures, religion, warfare, language, and much more, are the end result of natural selection working on the units of heredity. Even homosexuality could be biologically caused, as gay and lesbian members of the family aid close relatives, like sterile mammalian workers at the nest. Moreover, argued Wilson, while humans may be able to change some things, biology will be resistant and, in many respects, people are locked into being what they are. Utopian plans for change would be counterproductive.

Early objections to sociobiology

As expected, there were many objections to the new field of sociobiology. Social scientists became tense because they felt that biologists were poaching on their domain. Rather than accepting biology as a complement or an aid to social science, they saw it as a threat and feared sociology would vanish and sociobiology (social-group division) would take its place. Feminists abhorred what they considered a direct attack on their ideology, which held sexual differences and family structures to be purely cultural rather than biological constructions. Darwin was painted as the archetypical Victorian male chauvinist, and sociobiology was seen as an excuse for the status quo that oppresses women and children. Marxists, and this included some eminent biologists, felt that a biological approach was a travesty of the truth, because it pretended that evolution and natural selection had accomplished what was truly a function and result of economic deprivation. Their ideological ancestor, Friedrich Engels, had inveighed against a reductionist approach to understanding, and human sociobiology was the worst of all possible offenders.

Interestingly, the one group that might have been expected to explode—those members of the Christian community interested seriously in science—was far more receptive. Creationists, of course, would have nothing to do with any evolutionary science, and they fully enjoyed the controversy that pitted evolutionist against evolutionist. More moderate Christian thinkers reacted in a different way. Although they hardly welcomed human sociobiology with unalloyed joy, they could see that the new science was a serious approach to serious problems, and responded in this spirit. Even Christians drawn to feminism and Marxism realized that there was more to life than simple matters of culture, tradition, and economics. God, they argued, is not a social constructivist.

Later interpretations

By the dawn of the twenty-first century, much of the dust had settled. There is certainly no question that some of the early enthusiasts for sociobiology let their imaginations outstrip the evidence, filling in gaps with creative intelligence. But some of the most interesting work has come from evolutionists who have actually turned biology on its head. Sarah Hardy, for instance, has argued that female humans conceal ovulation, thereby ensuring that males have to stay around and participate in child rearing—if they do not, they cannot be sure of paternity. In other words, in good feminist fashion, she argues that the evolutionary scales are balanced, and may, if anything, be tipped in favor of women. Others have argued that sociobiology underlies the unity of the human community, thus belying fears of racism. People can, of course, interpret biology and form prejudices as they will, but there is no reason for thinking that biology supports or contains such prejudices.

In many other ways, human sociobiology transcends the parody portrayed by the critics. Typical of modern sociobiological research (often now hidden under less flamboyant and provocative names like human behavioral ecology or evolutionary psychology) is a careful study of homicide by the Canadian researchers Martin Daly and Margo Wilson. They have shown that murder falls into stable patterns, which lend themselves to a sociobiological interpretation. For example, the killing of children by parents (other than infanticide, which follows its own rules) is almost always perpetrated by step-fathers rather than biological fathers. This is a pattern very much in line with the rest of the animal world, where it is well-documented that males moving in on a new female will attack her already-existing young, so that their own new offspring get more attention. Paradoxically, when Daly and Wilson began their study, they could find no firm evidence against which to test their hypotheses. Authorities thought it prejudicial to reconstituted families to collect statistics on whether or not family violence involved step-parents or biological parents. It was only when Daly and Wilson insisted on the collection of the data, that the patterns emerged.

Implications for religion and philosophy

Sociobiology suggests much to the philosopher or the theologian interested in the deeper questions about human nature. Traditional approaches to evolution and ethics—so-called social Darwinism—argue that moral codes follow from the need to cherish and promote the evolutionary process. Thus, British philosopher Herbert Spencer endorsed laissez-faire economics in the name of evolution, seeing it as part of the struggle for existence in the human world. Just as in nature the weak fall because they are inadequate, so in society the weak fall because they are inadequate; this, argued Spencer and his fellows, is nature's way and to try to prevent it is to lead to decay and degeneration. Most sociobiologists avoid arguments of this type. Following more sensitive thinkers, like Darwin's "bulldog" Thomas Henry Huxley, sociobiologists refuse to identify the "evolved" with the "good." They see that although evolution can produce the worthwhile, evolution can also produce the absolutely horrible. Although Daly and Wilson think that child killing may be biologically motivated, they stress that it is not moral in any sense. Their work indeed is intended to throw light on the problem, so that people might change or control such behavior. Male lions and lemmings may kill the young of other males, but this is no reason for humans to do likewise.

There are, however, other ways to tackle issues of morality, while still bringing sociobiology to bear. First, one might argue, as many do, that humans are social animals in the extreme, and as such need mechanisms to get on with other humans. If humans did not have adaptations to protect against disease—as native Tasmanians did not—the human species would soon die out. The same is true of behavioral and motivational adaptations. By nature people are selfish—that is a direct consequence of the struggle for existence—but this selfishness, untamed and unmodified, would lead to disaster in social situations. People would quarrel and fight nonstop and be unable to work together. So they need special adaptations to overcome this counterproductive consequence of natural selection. But what could these adaptations be? Humans are too complex simply to have social sentiments hardwired in, like ants. Apart from anything else, simple hardwiring gives no room for reflection and regrouping when things go wrong or when facing new or unexpected situtations. Humans need something more subtle than the simple rules of social behavior followed by the hymenoptera. Here, argue sociobiologists, is the place for a moral sense, something that humans have innately (that is, put in place by selection and backed by the genes) that allows them to meet social demands and to work together with other humans. People have a sense of moral obligation that they ought to help others (and equally a sense of moral obligation that when they are in need, others ought to help them). It is something that aids people in social situations, and at the same time is obviously an instrument with sufficient subtlety and flexibility to allow people to adapt as situations and environments change. In other words, biologists of human social behavior argue that ethics has been put in place by human biology to make people good cooperators. Ethics is an adaptation.

The atheistic interpretation. What implications does this discussion have for the foundations of ethics (what philosophers call metaethics)? If ethics, the human sense of right and wrong, is an adaptation, is it thereby no more than a subjective sentiment, on a par with a liking for certain foods? The answer depends on one's theological commitments. Atheists and skeptics will probably conclude that there are no foundations, that ethics is simply an epiphenomenon of the genes, with no more ultimate meaning than any other adaptation like eyes or teeth. However, the tendency toward ethical behavior is not simply a subjective sentiment like a fondness for ice-cream. For a start, it has to be universally shared by other humans (except perhaps psychopaths), otherwise it would not function. Moreover, subjective emotion or not, it has to have an illusion of objectivity—of a foundation—otherwise it would simply collapse, as people decided to cheat and look after themselves alone. A conscience is essentially a part of the moral sense, even if (especially if) it is just an adaptation like everything else. But ultimately, the nonbeliever thinks that there is nothing to ethics but a naturalistic explanation of where it came from and why it has the hold on people that it does.

The Christian interpretation. What if one is a Christian or a member of any other theistic religion, however? Can this rather bleak philosophy take on a different, more hopeful and fulfilling hue? If one is a believer, one can (and must) surely interpret the situation as God's way of instilling an ethical sense in humankind. After all, the believer has to agree that God has instilled an ethical sense, and if one is an evolutionist then surely the sociobiological scenario is as plausible a scenario as any other. In fact, the Christian—certainly the Christian who takes seriously the teaching of Thomas Aquinas—knows this already. Natural law is something imposed upon us by the way that God has created humans. Human sexuality is intimately bound up with the fact that (in the first place) there are two sexes, and that to fulfill this sexuality people have the various emotions and organs that they do. Moral dictates follow from the nature of this creation. Promiscuity, for instance, is immoral because it is a violation of the natural—that is, God-made and God-ordained—bonds of erotic love that can and should exist between two people exclusively. For the theist who accepts sociobiology, ethics is part of creation, and the emotions and reasons that constitute it are very much part of the God-made natural order. Hence, inasmuch as one's moral sense (and the awareness to which it leads) is something natural, it is something to be cherished and obeyed and respected by God's creatures.

Sociobiology and original sin. But what about original sin? No one who has lived through even part of the past century can be insensitive to this issue, and those who were wont to downplay its significance in theology are now surely in the minority. How else does one—how else does the Christian—explain the evils of national socialism and all of the other vile movements of the past hundred years? The idea that humans are in some sense tainted—not wholly bad but with a dark side to their natures—is pressing on the nonbeliever and obligatory for those who think that Jesus was the Christ, the Son of God who died on the Cross for the sins of humans. The traditional position, that of Augustine of Hippo, is that the sins of Adam and Eve are transmitted to us all through sexual intercourse—people inherit their faults. No evolutionist can take this literally—indeed, it is unlikely that Augustine, who was sensitive to the development of knowledge and who had full awareness of the need to interpret the Bible allegorically, would now interpret the Adam and Eve story literally. He too would feel a need for revision.

A sociobiological approach shows a way of updating the belief in original sin—a way that takes modern science seriously and yet in no sense denies or belittles the significance of such sin. Sociobiology starts with the fact that humans are destined to be selfish animals—that is the way of natural selection. Group selection is no longer a viable mechanism, and all must be interpreted in the light of advantage to the individual. If people were not selfish—if they did not take for ourselves—then they would have become extinct long ago. But at the same time, sociobiology stresses that humans are social animals that need to get on together. So humans evolved ethics. But humans are not locked in blindly, like ants. They have moral sentiments, and though they may not have much choice about the moral sentiments—a fact that no one, other than existentialists at their most extreme, has ever denied—they can decide whether or not to obey the sentiments, as it pleases them. And sometimes it does please people, and sometimes it does not. Sometimes people continue in their selfish ways even though others would suffer, and sometimes they listen to conscience and do the right thing—sometimes indeed they do not even have to listen to conscience before doing the right thing. In other words, humans are an ambivalent mixture of good and ill—sometimes doing the kind and charitable thing, and sometimes failing in their obligations and duties. And humans are this way in their deepest nature, something they inherit rather than create anew. And that surely is precisely the Christian position on original sin. People are tainted. They cannot escape this. It is inherited as part of human nature. But humans have the abilities to do the right thing, to act against this side to their nature. Sometimes they do, and sometimes—all too often—they do not.

Freedom and determinism. Finally, one must address the question of freedom and determinism. It is an absolutely crucial part of Christian, as well as Jewish and Muslim, belief that people are made in the image of God, and therefore have the freedom to choose between good and ill. God may know what people will do, but God does not constrain them in what they will do. Each person's faults are his or her own responsibility. Can such a conception of freedom be reconciled with human sociobiology, a discipline that some critics complain is committed to genetic determinism? Those who dislike human sociobiology argue that sociobiologists portray humans as marionettes on the strings of the genes, with no more power of choosing right or wrong than the puppets Punch and Judy have of living in domestic harmony. People are as clockwork, set up and simply set to run. The wife beater resorts to violence because he is male and that is the way of men. The child whines because it is a child and that is the way of children. The racist has genes for xenophobia and is no more at fault that the person with Down syndrome who cannot pass an intelligence test. Biology is destiny, and that is the end to freedom.

A more thoughtful approach, however, shows that Christian conceptions of freedom and sociobiological conceptions of determinism are not necessarily contradictory and can indeed be complementary. On the one hand, the Christian recognizes that freedom does not mean stepping outside of the laws of nature, for in that direction lies randomness or madness. Augustine, again, saw that true freedom means working according to human nature. God is free and yet cannot do ill. It is against God's nature to do ill. Likewise, people are free, but what they do is part of their nature. That is why God knows what will happen even though God does not control or will it. People are free to kill their children and yet most could no more do so than they could jump over the Atlantic Ocean. They are free to refrain from boasting, and yet could no more do so than they could climb Mount Everest. Conversely, for all the talk about determinism, the sociobiologist recognizes, in fact insists on, a dimension of human freedom. Ants are hardwired to do what they do. They have no choice. But humans are not hardwired to do what they do. They do have a choice; they must have a choice if they are to function as the complex social animals they have evolved into. Humans may be part of the causal nexus, but they have a dimension of freedom denied to rocks or lower animals and plants. If ants are like cheap rockets shot off and then, once fired, beyond further control, humans are like expensive rockets with feed-back mechanisms enabling them to respond to changes in the target. In short, the Christian recognizes that human freedom takes place within rules and restraints, and the sociobiologist recognizes that human determinism is open to dimensions of choice and alternative action. Why then should not the Christian and the sociobiologist work together to find a meeting point on these issues, harmony rather than conflict? Far greater gaps exist between Christians and their critics than between sociobiologists and their critics.

Conclusion

Other issues could be raised, and some are still far from resolution. If evolutionary theory is true, then presumably human minds—in line with everything else biological—are part of gradual development in time. Yet Christians have tended to see minds (and souls) as a sharply demarcated phenomenon—either humans have them or they do not. Animals do not have souls; humans, all humans, do. There is a brittle break in nature at this point. This is certainly a place where some compromise is necessary if consistency is to be achieved. There is surely much work and serious rethinking still needed on the connection (if there is one) between the human mind, either the Christian human mind or the sociobiological human mind, and the teachings about the nature and existence of the immortal soul. But these and other problems are challenges, not road blocks. Certainly the larger Christian community was correct in its intuitions when, on the arrival of human sociobiology, it took a position of welcome, albeit guarded welcome, rather than of hostility and rejection. All human understanding is grist for the theological mill, and sociobiology is no exception.

See also BEHAVIORAL GENETICS; DARWIN, CHARLES; DETERMINISM; DNA; EUGENICS; EVOLUTION, BIOCULTURAL; EVOLUTION, BIOLOGICAL; FREEDOM; GENETIC DETERMINISM; GENETICS; MEMES; MUTATION; NATURE VERSUS NURTURE; SELFISH GENE; SIN

MICHAEL RUSE