Nature Versus Nurture

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NATURE VERSUS NURTURE

This familiar expression indicates a division between those who offer biological explanations for some human behaviors and those who insist on environmental explanations. The root of the problem is a basic uncertainty about the causes of human physical and psychological traits. Some traits are obviously inherited in a biological sense, such as having a four-chambered heart or the ability to learn to talk. Such characteristics are said to belong to humans by nature, from a root word meaning birth. Other traits are not inherited, but are a result of environmental influences. A person can inherit a parent's hair color, but not his or her tattoo; and a person must learn the French language in order to speak it. Acquired traits are said to be due to nurture, which in this context indicates any influence other than biological inheritance.

Distinguishing in Specific Cases

In analyzing physical characteristics, it can be difficult to tease nature and nurture apart. Why is Steve eight inches taller than Ric? Perhaps this difference is only natural because Steve's parents are taller than Ric's parents. But the difference in stature could quite literally be due to nurture: Perhaps Ric was starved as an infant. Then again, it may be the result of both: Steve picks up five inches from his Mom and Dad, and another three at the dinner table. The problem is much more difficult when analyzing behavior because the range of possibilities is greater. Natural influences on behavior might be quite strong, so that culture plays only a marginal role. At the other extreme, it may be that human beings are born with almost no instincts or innate ideas. Perhaps the only significant influence on any person's behavior is the behavior of other persons, living and dead.

This uncertainty regarding the relative weight of nature and nurture quickly becomes a controversy when discussing behaviors of greater significance. For example, suppose boys are more aggressive at play and girls more caring. One explanation is that society creates this gender difference by giving toy guns to boys and baby dolls to girls. It is possible, however, to argue the opposite: Because girls are already inclined toward motherhood, they receive the dolls they want; and because boys are more aggressive from birth, they select toys that look like weapons. This sort of question tends to divide scholars into hostile camps. Naturalist Edward O. Wilson has dubbed those who offer the second explanation hereditarians. Those who insist on the former, he calls nurturists.

Hereditarians vs. Nurturists

The opposing beliefs of hereditarians and nurturists colors almost all contemporary discussions of human behavior and its causes. A minor cause of the debate is an old turf war between the social sciences and the humanities, on one side, and the physical sciences, on the other. Some sociologists and English professors see explaining what people think, say, and do, in part by reference to genes, proteins, and neurons, as an invasion of their territory by physicists and biologists. This invasion is especially unnerving because fields such as psychology or history can never hope to match the precision, clarity, and predictive power of the hard sciences. Nurturism is an attempt to carve out a space in which the soft sciences do not have to compete with physics.

The major cause of the conflict between the soft and hard sciences arises from the political, ethical, and aesthetic implications of the hereditarian's view. Any influence that biology is allowed over human behavior seems to come at the expense of moral responsibility. Many facts about existing societies strike people as unjust: sexual inequality, crime and war, economic inequality, among others. To the extent that these social ills are due to nature, society cannot blame anyone for them. Nurturists prefer arguing that the hereditarian view always justifies the status quo. It certainly seems to undermine the indignation that might drive any fundamental change.

The hereditarian view also seems to place limits on the range of possible reforms. If male aggression and desire for status are natural, then every society will suffer from some measure of crime and inequality. If human beings have an instinct to divide themselves into mutually hostile groups, as do chimpanzees, then no society will be free from ethnic, racial, or religious conflict. If women naturally desire to care for their own children, then there is little hope of transforming child-rearing into an altogether collective activity, as many utopian communities have attempted to do. The hereditarian view does not deny the possibility of reform, but it does suggest that the best societies will be only marginally better than the ones that have always existed. Nurturists tend to be offended by this idea.

Proposed Resolutions

If an intellectual impasse goes unresolved long enough, some will inevitably grow tired of it and look for a way out. The oldest peace plan is a form of dualism involving the construction of a demilitarized zone between the study of nature and the study of culture. Natural scientists would be allowed to study all natural processes, including human evolution; but should resist any temptation to explain such things as human social and political behavior, history, art or literature by reference to nature. The study of culture should be regarded as an autonomous and independent field of inquiry.

Another attempt to resolve the issue involves a holistic approach to nature and nurture. Much of the anxiety over natural explanations of behavior relies on an overly simplistic view of genetic causation. In that view causation works one way: Genes create proteins that in turn create organisms. A person's nature is fixed from the beginning, and there is very little that can be done about it. The holistic approach is based on a more complex view. Many genes spend their time switching other genes on and off, often in response to external information. A person's genetic code may be fixed, but genetic nature is not: It molds itself in response to the environment. Moreover many genes cannot function without information from the environment. Human beings are born with a capacity to learn language, but they must be exposed to a language during certain critical periods in development in order to learn it. Here culture is as much a part of nature as are genes.

Both dualism and holism present themselves as compromises, but are in fact attempts to win by default. Only those who believe that biology has almost no influence over individual personalities will take dualism seriously. Likewise although holism presents a very flexible version of human nature, it nevertheless makes hereditarian assumptions about the influence of biology on behavior. The argument between nurturists and hereditarians does seem likely to wind down for the simple reason that hereditarians are winning. There is little doubt remaining that genes do influence significant behaviors, and that in many cases—twin studies for example—biological inheritance is a much better predictor of an individual's life course than social environment.

Ethical and Political Significance

The moral and political significance of the difference in opinion between nurturists and hereditarians is more difficult to decipher. If the expression of genes really does change in response to the environment, culture may be as difficult to change as nature. Almost every child will easily master a first language, but few people learn a second language well enough to pass for a native. Perhaps this is because one's first language shapes the mind in more or less permanent ways. Evidence suggests that the infant mind is primed to learn language, and much the same thing may be true of morality and other aspects of political culture. Similarly acknowledging that people are naturally disposed to certain behaviors probably makes them more, rather than less, responsible. An individual who recognizes a personal propensity to alcoholism or spousal abuse, is better able to take responsibility for the condition.

The hereditarian view may be liberating in a much more profound way. For example the debate over admitting women into the military has usually turned on whether one believes that sexual differences are mostly due either to socialization or to nature. However the opposite should also be true. Males not only make up most of the soldiers in every society, they also commit almost all the violent crimes. If women serve in large numbers in the military, society must ask what effect this will have on their behavior after their military service is concluded. There is no great need to worry if psychological dimorphism is natural because no change in social environment will make women as dangerous as men. But if these behavior patterns are socially constructed, introducing women into the military might have disastrous consequences. If women learn to behave like men, not only on the battlefield but back home, the crime rate in a society could easily double. Contrary to popular belief, the hereditarian view may be friendlier to social reform than the nurturists view.

The tension between nature and nurture is at least as old as Plato's Timaeus. According to premodern natural philosophy, nature was largely fixed, and was superior in dignity and authority to any product of technology; only nurture was in large measure subject to human control. In this view the role of such sciences as agriculture, medicine, or politics was to tend nature as one had tended the god, in order to promote human flourishing.

The early moderns rejected this approach, and chose to view nature as a "rich storehouse" of materials, as English philosopher Francis Bacon (1561–1626) said, to be manipulated "for the relief of man's estate." The distinction between nature and nurture was relatively unimportant: Given the right technologies, either can be brought under the yoke of human will. Human beings thus acquire an unprecedented sense of responsibility for their own destiny.

Some of that early modern confidence remains in the early 2000s; however, it has been tempered by other considerations. For example the human genome project promised to provide a powerful new tool for the diagnosis and treatment of disease; however, about 5 percent of its budget was devoted to exploring the ethical and social consequences of this project. This was in part political: The public neither fully understands nor trusts innovative technologies. But it also recognizes the limits of engineering as a metaphor for technology. Much of nature as well as human behavior remains stubbornly resistant to technoscientific ambitions. This may be because human life rests on a vast array of interactions between biology and culture, an array that is too complex ever to be mastered. Perhaps an approach to nature and nurture that combines modern science and technology, with at least a dose of ancient piety, is necessary.

KENNETH C. BLANCHARD, JR.