The Meaning of Human Existence

by Edward O. Wilson

  Not to worry. By the time the process has set in, likely in this century, the role of science and high technology will, as expected, be beneficent and far more pervasive than now. But—and this is the most important part—science and technology will also be the same everywhere, for every civilized culture, subculture, and person. Sweden, the United States, Bhutan, and Zimbabwe will share the same information. What will continue to evolve and diversify almost infinitely are the humanities.

  For the next few decades, most major technological advances are likely to occur in what is often denoted BNR: biotechnology, nanotechnology, and robotics. In pure science the secular grails now sought along the broad frontier include the deduction of how life originated on Earth, along with the creation of artificial organisms, gene substitution and surgically precise modification of the genome, discovery of the physical nature of consciousness, and, not least, the construction of robots that can think faster and work more efficiently than humans in most blue-collar and white-collar labor. At the present time these envisioned advances are the stuff of science fiction. But not for long. Within a few decades they will be reality.

  And the cards are now on the table, faceup. First on the agenda is the correction of the more than a thousand genes for which rare mutant alleles have been identified as the cause of hereditary diseases. The method of choice will be gene substitution, replacing the mutant allele with a normal one. Although still in the earliest, mostly untested stage, it promises eventually to replace amniocentesis, which allows first a readout of the embryonic chromosome structure and genetic code, then therapeutic abortion to avoid disability or death. Many people object to therapeutic abortions, but I doubt that many would object to gene substitution, which can be compared with replacement of a defective heart valve or diseased kidney.

  An even more advanced form of a volitional evolution, albeit indirect in cause, is the homogenization ongoing among the world populations by increased emigration and interracial marriage. The result is a massive redistribution of Homo sapiens genes. Genetic variation between populations is declining, genetic variation within populations is increasing, and, as an overall result, the genetic variation of the species as a whole is also increasing—the last dramatically so. These trends create a dilemma of volitional evolution likely to catch the attention of even the most myopic political think tanks in a few decades. Do we wish to guide the evolution of diversity in order to increase the frequency of desirable traits? Or increase it still more? Or finally—this will almost certainly be the short-term decision—just leave it alone and hope for the best?

  Such alternatives are not science fiction, and they are not frivolous. On the contrary, they are linked to yet another biology-based dilemma that has already entered public discussion, ranking with contraceptives in high school and evolution-free textbooks in Texas. It is this: With more and more decision making and work done by robots, what will be left for humans to do? Do we really want to compete biologically with robot technology by using brain implants and genetically improved intelligence and social behavior? This choice would mean a sharp departure away from the human nature we have inherited, and a fundamental change in the human condition.

  Now we are talking about a problem best solved within the humanities, and one more reason the humanities are all-important. While I’m at it, I hereby cast a vote for existential conservatism, the preservation of biological human nature as a sacred trust. We are doing very well in science and technology. Let’s agree to keep it up, and move both along even faster. But let’s also promote the humanities, that which makes us human, and not use science to mess around with the wellspring of this, the absolute and unique potential of the human future.

  6

  The Driving Force of Social Evolution

  Few questions in biology are as important as the evolutionary origin of instinctive social behavior. To find the correct answer is to explain one of the great transitions in levels of biological organization, from the organism to the superorganism—from one ant, say, to an organized colony of ants, and from a solitary primate to an organized society of human beings.

  The most complex forms of social organization are made from high levels of cooperation. They are furthered with altruistic acts performed by at least some of the colony members. The highest level of cooperation and altruism is that of eusociality, in which some colony members surrender part or all of their personal reproduction in order to increase reproduction by the “royal” caste specialized for that purpose.

  As I’ve pointed out, there are two competing theories of the origin of advanced social organization. One is the standard theory of natural selection. It has proved correct across a broad range of social and nonsocial phenomena, improving in precision since the origin of modern population genetics in the 1920s and modern synthesis of evolutionary theory in the 1930s. It is based on the principle that the unit of heredity is the gene, which typically acts as part of a network of genes, and the target of natural selection is the trait prescribed by the gene. For example, an unfavorable mutant gene in humans is that which prescribes cystic fibrosis. The gene is rare because its phenotype cystic fibrosis is selected against—it lowers longevity and reproduction. Examples of favorable mutant genes are those that prescribe adult lactose tolerance. After originating in dairying populations in Europe and Africa, the phenotype prescribed by the mutated genes made milk available as a reliable adult food, and thereby increased the comparative longevity and reproduction of the people possessing them.

  A gene for a trait that affects a group member’s longevity and reproduction relative to other members in the same group is said to be subject to individual-level natural selection. A gene for a trait entailing cooperation and other forces of interaction with fellow group members may or may not be subject to individual-level selection. In either case it is also likely to affect longevity and reproduction of the group as a whole. Because groups compete with other groups, in both conflict and their relative efficiency in resource extraction, their differing traits are subject to natural selection. In particular, the genes prescribing interactive (hence social) traits are subject to group-level selection.

  Here is a simplified scenario of evolution according to the standard theory of natural selection. A successful thief furthers his own interests and those of his offspring, but his actions weaken the remainder of the group. Any genes proscribing his psychopathic behavior will increase within the group from one generation to the next—but, like a parasite causing a disease in an organism, his activity weakens the rest of the group—and eventually the thief himself. At the opposite extreme, a valiant warrior leads his group to victory, but in doing so is killed in battle, leaving few or no offspring. His genes for heroism are lost with him, but the remainder of the group, and the heroism genes they share, benefit and increase.

  The two levels of natural selection, individual and group, illustrated by these extremes, are in opposition. They will in time lead to either a balance of the opposing genes or an extinction of one of the two kinds altogether. Their action is summarized in this maxim: selfish members win within groups, but groups of altruists best groups of selfish members.

  The theory of inclusive fitness, in opposition to the standard theory of natural selection, and with it the established principles of population genetics, treats the individual group member, not its individual genes, as the unit of selection. Social evolution arises from the sum of all the interactions of the individual with each of the other group members in turn, multiplied by the degree of hereditary kinship between each pair. All the effects of this multiplicity of interactions on the individual, both positive and negative, make up its inclusive fitness.

  Although the controversy between natural selection and inclusive fitness still flickers here and there, the assumptions of the theory of inclusive fitness have proved to be applicable only in a few extreme cases unlikely to occur on Earth or any other planet. No example of inclusive fitness has been directly measured. All that has been
accomplished is an indirect analysis called the regressive method, which unfortunately has itself been mathematically invalidated. The use of the individual or group as the unit of heredity, rather than the gene, is an even more fundamental error.

  At this point, prior to developing the theories further, it will be instructive to take a specific example in the evolution of social behavior and see how it is treated respectively by each approach.

  The life cycle of ants has always been a favorite of inclusive fitness theorists as offering proof of the role of kinship and the validity of inclusive fitness. Many ant species have the following life cycle: their colonies reproduce by releasing virgin queens and males from the nest. After mating, the queens do not return home, but disperse to establish new colonies on their own. The males die within hours. The virgin queens are much larger than the males, and colonies invest a correspondingly larger fraction of their resources to their production.

  The inclusive fitness explanation of the size difference between the sexes, introduced in the 1970s by the biologist Robert Trivers, is as follows. The means of sex determination in ants is peculiar, such that sisters are more closely related to one another than they are to their brothers (providing the queens mate with only one male). Because the workers raise the young, Trivers continued, and because they favor sisters over brothers, they invest more in virgin queens than in males. The colony, with workers in control, accomplish this end by making the queens individually much larger in size. This process deduced with inclusive fitness theory is called indirect natural selection.

  The standard population genetics model, in contrast, posits direct natural selection and tests it with direct observation in the field and laboratory. The larger size of the virgin queen is necessary, as all entomologists know, because of the way she starts a new colony. She digs a nest, seals herself in, and raises the first brood of workers on her large bodily reserves of fat and metabolized wing muscles. The male is small because its only function is to mate. After achieving insemination, it dies. (Queens live on in a few species, incidentally, for more than twenty years.) The roundabout inclusive fitness explanation for investments according to gender is therefore wrong.

  The assumption of inclusive fitness theory that workers control the colony’s allocation, a crucial point in this reasoning, is also wrong. Using the valve on her spermatheca, the bag-like organ in which the sperm are stored, the queen determines the sex of the offspring born. If a sperm is released to fertilize an egg in the queen’s ovary, a female is born. If no sperm is released, the egg is not fertilized, and from the unfertilized egg a male is born. Thereafter, a complex of factors, only some of which are under worker control, determine which female eggs and larvae will become queens.

  For half a century, while data were still relatively scarce, the theory of inclusive fitness was the prevailing explanation of the origin of advanced social behavior. It began in 1955 with a simple mathematical model by the British geneticist J. B. S. Haldane. His argument was in the following form (which I’ve altered here a bit to make it intuitively easier). Imagine that you are a childless bachelor standing on a riverbank. Looking out over the water, you see that your brother has fallen in and is drowning. The river that day is raging, and you’re a poor swimmer, so you know that if you jump in and save him, you yourself will probably drown. So the rescue requires altruism on your part. But (Haldane said) it does not also require altruism on the part of your genes, including those responsible for making you altruistic. The reason is the following. Because the man is your brother, half of his genes are identical to yours. So you jump in, save him, and sure enough, you drown. Now you’re gone, but half of your genes are saved. All your brother has to do in order to make up the loss in genes is to have two additional children. The genes are the unit of selection; the genes are what count in evolution by natural selection.

  In 1964, another British geneticist, William D. Hamilton, expressed Haldane’s concept in a general formula, which came to be known in later years as the Hamilton inequality. It said that a gene prescribing altruism, such as that of the heroic brother, will increase if the benefit in number of offspring to the recipient exceeds the cost in offspring to the altruist. However, this advantage to the altruist will be effective only if the recipient and the altruist are closely related. The degree of kinship is the fraction of genes that are shared by the altruist and recipient due to their common descent: one-half between siblings, one-eighth between first cousins, and so on in a rapidly declining rate as the degree of kinship becomes more distant. The process later came to be called kin selection. It seemed, at least from this line of reasoning, that close kinship is the key to the biological origin of altruism and cooperation. Hence close kinship is a primary factor of advanced social evolution.

  On the surface, kin selection seemed at first to be a reasonable explanation for the origin of organized societies. Consider any group of individuals that have come together in one manner or another but remain unorganized—a fish school, for example, a flock of birds, or a local population of ground squirrels. The group members, let us say, are able to distinguish not just their own offspring, leading to evolution of parental care by standard (Darwinian) natural selection. Suppose they also recognize collateral relatives related by common descent such as siblings and cousins. Allow further that mutations occur that induce individuals to favor close collateral relatives over distant relatives or nonrelatives. An extreme case would be Haldane’s heroism biased toward a brother. The result would be nepotism, resulting in a Darwinian advantage over others in the group. But where does that lead an evolving population? As the collateral-favoring genes spread, the group would change into an ensemble not of competing individuals and their offspring, but of an ensemble of parallel competing extended families. To achieve group-wide altruism, cooperation, and division of labor, in other words organized societies, requires a different level of natural selection. That level is group selection.

  Also in 1964, Hamilton took the kinship principle one step further by introducing the concept of inclusive fitness. The social individual lives in a group, and it interacts with other members of the group. The individual participates in kin selection with each of the other group members with which it interacts. The added effect it has on its own genes passed into the next generation is its inclusive fitness: the sum of all the benefits and costs, discounted by the degree of kinship with each other group member. With inclusive fitness the unit of selection had passed subtly from the gene to the individual.

  At first I found the theory of inclusive fitness, winnowed down to a few cases of kin selection that might be studied in nature, enchanting. In 1965, a year after Hamilton’s article, I defended the theory at a meeting of the Royal Entomological Society of London. Hamilton himself was at my side that evening. In my two books formulating the new discipline of sociobiology, The Insect Societies (1971) and Sociobiology: The New Synthesis (1975), I promoted kin selection as a key part of the genetic explanation of advanced social behavior, treating it as equal in importance to caste, communication, and the other principal subjects that make up sociobiology. In 1976 the eloquent science journalist Richard Dawkins explained the idea to the general public in his best-selling book The Selfish Gene. Soon kin selection and some version of inclusive fitness were installed in textbooks and popular articles on social evolution. During the following three decades a large volume of general and abstract extensions of the theory of kin selection was tested, especially in ants and other social insects, and purportedly found proof in studies on rank orders, conflict, and gender investment.

  By 2000 the central role of kin selection and its extensive inclusive fitness had approached the stature of dogma. It was a common practice for writers of technical papers to acknowledge the truth of the theory, even if the content of the data to be presented were only distantly relevant to it. Academic careers had been built upon it by then, and international prizes awarded.

  Yet the theory of inclusive fitness was not just wr
ong, but fundamentally wrong. Looking back today, it is apparent that by the 1990s two seismic flaws had already appeared and begun to widen. Extensions of the theory itself were growing increasingly abstract, hence remote from the empirical work that continued to flourish elsewhere in sociobiology. At the same time the empirical research devoted to the theory remained limited to a small number of measurable phenomena. Writings on the theory mostly in the social insects were repetitive. They offered more and more about proportionately fewer topics. The grand patterns of ecology, phylogeny, division of labor, neurobiology, communication, and social physiology remained virtually untouched by the asseverations of the inclusive theorists. Much of the popular writing devoted to it was not new but affirmative in tone, declaring how great the theory was yet to become.

  Inclusive fitness theory, fondly called IF theory for short by its defenders, was showing increasing signs of senescence. By 2005 questions about its soundness were being openly expressed, especially among leading experts on the details of the biology of the ants, termites, and other eusocial insects, as well as a few theoreticians bold enough to seek alternative explanations of the origin and evolution of eusociality. The researchers most committed to IF theory either ignored these deviations or summarily dismissed them. By 2005 they had gained enough representation in the anonymous peer review system to hinder publication of contrary evidence and opinions in leading journals. For example, a keystone early support of inclusive fitness theory, cited in textbooks, was the prediction of overrepresentation of the Hymenoptera (bees, wasps, ants) among eusocial animal species. When after a time one investigator pointed out that new discoveries had nullified the prediction, he was told, in effect, “We already knew that.” They did know that, but hadn’t done more than just drop the subject. The “Hymenoptera hypothesis” was not wrong; it had just become “irrelevant.” When a senior investigator used field and laboratory studies to show that primitive termite colonies compete with one another and grow in part by the fusion of unrelated workers, the data were rejected on grounds that the conclusion did not adequately take into account inclusive fitness theory.