Five—
Human Nature and Culture:
Biology and the Residue of Uniqueness

Melvin Konner

I

Since the question, "Is there such a thing as human nature?" continues to be posed, and to be answered by some in the negative, it seems necessary to being by exploring the meaning of this question and showing why it cannot, in any meaningful form, have any but an affirmative answer. The question raises doubts about whether aspects of the human condition can be considered inevitable outcomes of biological elements in the human makeup. In extreme forms, such doubts are dubious. If I assert that it is human nature to require a diet supplying eight essential amino acids, to walk bipedally, and to speak a language containing nouns and verbs, there are only a few ways to question the validity of the claim.

For example, it is possible to point to a small number of individuals who, from birth onward, are poisoned by an amino acid essential to all others, or who are never able to walk or speack, but these observations—which might be called the "rare-defect objection"—do not detract from the power of the generalizations. Second, and somewhat more interesting, it is easy to show that great variability exists in the way these generalizations are fulfilled by individuals and groups and that most of this variability is due to cultural or environmental causes. But these observations, the "cross-cultural objection," do not address the point that there is, in each of the systems in question, a core of features that do not vary. Third, there is the "freedom-of-will" objections: some individuals perfectly capable of walking will choose never to do so, while others may learn to walk faster or more gracefully than anyone in the world, or even to walk on their hands.

There are several answers to this objection, but two are decisive. First,

such freedom of will exists, but the rarity with which it is exercised, at least at the extremes of the distribution of behavior, is not irrelevant to the question at hand. This answer resembles the reply to the rare-defect objection but is directed to motivation rather than capability, and it implies that motivations as well as capabilities may be legitimately included in the definitional sphere of human nature, a point to which we will return.

Second, within the definable but admittedly broad band of variation in patterns of walking resulting fromt he exercise of freedom of will, it is possible to show lawful relations between human choices and physiological outcomes. After the choice has been exercised—for a given daily amount of walking, say—there follow predictable consequences for the structure and function of muscle, bone, and the cardiopulmonary organs. These, in turn, have consequences for behavioral capability, health, and life span. The laws relating the precise specturm of choices to the predictable outcomes are also part of what is meant by human nature. (Here perhaps a counterobjection will be raised: "But that is just what I mean. Human behavior is flexible, so much so that biology itself is under the sway of human choices." Of course it is; but predictably so, and with thresholds and limits provided by human nature—by the genes—and not by human choices. Biological concepts such as facultative adaptation, range of reaction, and bounded learning, among others, have been developed to describe parallel phenomena in nonhuman species.)

Finally, the "so-waht objection" holds that the sorts of characteristics legitimately subsumed under the rubric of human nature are trivial and uninteresting. "Of course everybody can walk; so what? It's the variations that are interesting." It might be pointed out that every person who can walk exhibits a relatively stereotyped heel-toe progression with synchronized alternate arm swinging, reflecting a very complex wired-in coordinating pattern involving many millions of neurons. Or that every child assumes the ability to walk within a narrowly defined age period because of the maturation of certain parts of the nervous system, the growth of which are under genetic control. But then each successive complexity pointed out becomes subsumed under the ho-hum or sowhat rubric, so that as soon as it is shown to be biologically determined, it will be deemed uninteresting. "That's not what I mean by human nature" will retreat to encompass only that which has not yet been given a biological basis.

Of course, what most of us mean by human nature is not primarily the dependence on certain nutrients or the ability to walk and talk but the condition of being subject to certain patterns of motivation that seem to constrain human freedom, and to this extent, the so-what objection really does apply to the characteristics we have considered so

far. I will insist int he end that human nature fairly includes, in fact must include, certain characteristically human—that is, genetically coded, wired-in—perceptions, cognitions, competencies, response systems, and motor action patterns as well as motivations. Indeed, it is doubtful whether motivation can meaningfully be defined so as to exclude such other psychological characteristics. But it is necessary at this point for us to leave the safe realms of amino acids and coordinated locomotion for the more treacherous realms of love, fear, sacrifice, selfishness, lust, and violence, which come most readily to the mind when the concept of human nature is invoked, and to establish the extent to which these realms are subject to the kinds of arguments applicable in the safer ones.

To do this properly requires a series of intellectual strategies directed at exploring the phylogenetic origins of the pattern; the evolutionary, principally selective forces that have operated and continue to operate on it; the cross-cultura and other variability in it (or lack thereof) and the lawful relationships between the variability and variations in the environment that might be expected to influence it; the immediate physiological antecedents of the pattern; the sequence of development of the pattern, including both the maturational and environmental components; and the genetics of the pattern, as explored through both classical Mendelian methods and the methods of molecular and developmental genetics.

Each of these intellectual strategies has progressed so far in the last two decades as to render suspect any opinion on human nature that does not give clear evidence of having kept abreast of their progress. It is not possible here to review their implications even in relation to one of the motivational patterns of interest. However, it is possible to touch on some of the highlights relevant both to human motivation in general and to a legitimate concept of human nature (Konner 1982b ).

II

The fossil evidence for human and proto-human evolution has accumulated steadily for more than one hundred years so no one familiar with it doubts the reality and continuity of that evolution (Ciochon and Fleagle 1987), However, new discoveries are made each year which change the details of the picture, and during the past tow decades, biochemical taxonomy has further altered our concept of human evolution. There is, therefore, little to be gained for our purposes in closely following each argument in human paleontology. But there is much to be gained from understanding the general higher primate background of human evolution; the environment of human evolutionary adaptedness, that of hunt-

ing and gathering; and the principles of evolutionary adaptation as applied to behavior and reproduction.

All higher primates without exception are social animals with great learning capacity and with the mother-offspring bond at the center of social life (Cheney, Seyfarth, and Smuts 1986). This bond is always prolonged, as is the anatomic and behavioral course of individual development, including each phase of the life cycle as well as the life span as a whole. Laboratory and field studies alike demonstrate the capacity for complex social cognition and social learning, up to and including "cultural" transmission of social rank, tool-using techniques, and knowledge of location of food sources. Play, especially social play, is characteristic of all primate species, particularly during development, and there are various reasons to believe it to be an important opportunity for learning. For example (MacLean 1985), the higher primate emphasis on both the mother-infant bond and on play represents an intensification of the pattern established by the early mammals and is essential to the understanding of the phylogeny of the limbic system and the emotions.

Primate groups generally include a core of genetically related individuals with associated nonrealtives. In most instances, the core is a matrilineage, stable over the life course of the individuals. In any case, the distribution of acts of social support and generosity is preferentially toward genetic relatives but not exclusively so. Monkeys and apes aid nonrelatives and can usually expect some aid in return. Cooperation is ubiquitous, but so is competition, and one of the major purposes of cooperation is mutual defense against other group members. Conflict is frequent, with both sexes participating but with males generally exhibiting more physical aggression than females.

Beyond these broad generalizations, great variation exists in social organization both between and within species (Napier and Napier 1985). Monogamy is present in some South American monkeys, in gibbons, and in one or two other forms, but in most species, larger group associations subsuming more temporary (although sometimes more than transient) associations between individual males and individual females are the rule. The causes of this variation in higher primate social organization remain obscure, but some relevant evolutionary principles will be considered below.

Although there are important species variations, it may be generally said that higher primates are sensitive to significant perturbations of the early social environment, such as isolation rearing or repeated involuntary mother-infant separation, and that these perturbations give rise to abnormalities of sexual, maternal, and aggressive behavior that in humans would be viewed as psychopathology (Harlow 1963, 1969; Arling and Harlow 1967; Sackett et al. 1981). In a number of species

(though not all), isolation rearing gives rise to stereotyped behavior such as rocking and self-directed aggression, and mother-infant separation gives rise to symptoms usually described as protest followed by depression. Even deprivation of contact with peers during development has produced abnormal behavior in some experiments. Apparent human analogues of these causal relationships, although difficult to interpret, have encouraged the use of primate models. These experiments emphasize the extent to which the noraml development and behavior in such animals has come to depend, in the course of evolution, on an intact social matrix.

Natural variation in stable individual behavior patterns ("personality") occurs in free-ranging monkey and ape groups (Smuts 1985) and extends to variants that would be considered pathological if seen in humans, such as hyperaggressive, isolative, phobic, or depressed behavior. It is rarely possible to explore the causes of such variants, but most are probably both genetic and environmental in origin. Some abnormalities, such as severe depression (as in the case of an eight-year-old wild chimpanzee after the death of his mother) may be incompatible with survival (Goodall 1986). Others, however, such as hyperaggressiveness (as in the case of two female chimpanzees that systematically and repeatedly killed the infants of other females) may actually enhance reproductive adaptation for the abnormal individual.

The above generalizations can be considered applicable to the social and psychological world of proto-human higher primate species for a period of approximately 40 million years. Against this background, hominids evolved during the last few million years, culminating in the emergence of our species within the last few hundred thousand years, and finally in the appearance of truly modern Homo sapiens within the last hundred thousand. Aside from the increase in intelligence, as indicated by increasing relative and absolute brain size as well as by increasing complexity of stone tools, one hallmark of the transition to hominids was an increasing reliance on hunting. All monkeys and apes are largely vegetarians and insect-eaters; instances of meat-eating are instructive but relatively infrequent.

Among the most technologically primitive humans, whether in the fossil record or in the ethnographic one, hunting is invariably of major importance (Lee and DeVore 1968, Dahlberg 1981). Most of the stone tools that have survived archaeologically were sued in hunting or butchering, and the demands caused by this activity have long been held to be central to the emergence of human intelligence and social organization. Recent evidence has shown that the stone used for this purpose had to be traded over long distances, implying unexpectedly complex social networks among our ancestors before 2 million years ago. Furthermore,

even chimpanzees share meat after a kill (but not plant foods), and among human hunter-gatherers, the following of elaborate regulations for such sharing of meat may be a life-and-death matter. Finally, with one noteworthy exception (the Agta of the Philippines, where women routinely hunt), all hunting and gathering societies in the ethnographic record have a division of labor by sex, with men doing almost all the hunting and providing meat for their families and women providing most of the vegetable foods. These features of soceity related to hunting had to have been grafted onto an already complex social life characteristic of nonhuman higher primates.

However, this traditional male-centered view gives at most half the story (Dahlberg 1981). In many hunting and gathering societies, plant foods gathered by women constitute more than half of the diet. Plant foods are shared in these societies (although not beyond the immediate family), while they are not shared in nonhuman primates. The early advent of upright posture may have had more to do with the need for females to carry plant foods as well as infants to a base camp than with any advantage upright posture conferred in hunting, and it may be that among the first tools invented were digging sticks and carrying devices for plants or infants—tools that, however crucial, would not be preserved in archaeological assemblages and that would most likely have been invented by women.

Psychodynamic theorist John Bowlby coined the phrase "the environment of human evolutionary adaptedness," which aptly describes the hunting and gathering way of life. The phrase correctly implies that this is, or was, the context for which natural selection prepared us and from which we have departed only in the past 10,000 years, a very short time in evolutionary terms. (The industrial revolution, in the same terms, happened only a moment ago.) From many studies of recent hunting and gathering peoples, combined with archaeological evidence of those of the distant past, it is possible to make certain generalizations about this context (lee and DeVore 1968): social groups were usually small, ranging in size from fifteen to forty people related through blood or marriage; groups were nomadic, moving frequently to take advantage of changing subsistence opportunities, and flexible in composition, size, and adaptive strategies; daily life involved physical challenge, vigorous exercise, and occasional hunger but with a usually dependable food base from a moderate work effort and with a marked division of labor by gender; disease, mainly infectious rather than chronic, produced high rates of mortality especially in infancy and early childhood, with consequent frequent experience of loss; virtually all of life's activities were done in a highly social context with people one knew well, often the same people for different activities; and privacy was limited, but creative ex-

pression in the arts was frequently possible, and conflicts and problems were dealt with through extensive group discussions.

These generalizations describe the context in which most of human evolution and prehistory have occurred, so it is often said that we are, in effect, hunter-gatherers in skyscrapers. Simplistic observations about the consequences of this change are often made and are not helpful. Mental illnesses, both major and minor, are present in such societies. All of them experience some level of violent conflict, up to and including homicide. Other human behaviors usually considered undesirable, such as selfishness, deceit, adolescent rebellion, adultery, desertion, and child abuse, occur in such societies, and it is impossible to compare the rates of such behaviors to those in our own society. Although fluid in their way, life in such societies is restricted to a much smaller number of people than ours, and the lack of privacy and inability to get away from those people must constitute stresses, just as crowding and high levels of contact with strangers may constitute stress in advanced societies. The stresses of illness and mortality, as well as the stresses and uncertainties of the daily food quest, also must take their toll. A truly thoughtful set of observations and analyses of the differences between psychological conditions in our society and the kind of society in which we spent most of our history could be imagined but has not yet been made.

III

Since the late 1960s, there has been rapid emergence of an influential new field of evolutionary study known as neo-Darwinian theory or, more commonly, sociobiology (Wilson 1975, Trivers 1985). This new set of principles has been quickly adopted by most investigators who study animal behavior under natural conditions, including ethologists and behavioral ecologists, and has also influenced many anthropologists and psychologists. Briefly summarized, the principles are as follows (Trivers 1985):

An organism is, in essence, a gene's way of making another gene. Put more strictly, it is a way found by up to thousands of genes, though shortor long-term cooperation, to make copies of themselves. As long as it is admitted that there can be no forces operating in nature other than physicochemical ones, it must be admitted that continued membership in an ongoing germ plasm is the only goal served by any given gene. To the extent that a gene influences behavior, it can only continue in the germ plasm if it maintains or enhances, through the behavior, the number of copies of itself in the gene pool of the next generation. (Contrary to a frequently repeated confusion, the cohesiveness of the genome has only quantitiative, not qualitative, bearing on the validity of this Principle.)

Genes increase their number by enhancing reproductive success. Enhancing survival is only one way of doing this. Where the two goals, enhancing survival and enhancing reproductive success, are in conflict, as they often are, genes that enhance reproductive success will replace genes that enhance survival. The concept of fitness in evolutionary theory has no meaning except the relative frequency of characteristics and of the genes that influence them. It is a tautological description of reproductive success and has nothing necessarily in common with medical, social, or athletic definitions of fitness, all of which can be and often are achieved without an increase, or even with a decrease, in technically defined reproductive fitness.

Fitness is now best defined as inclusive . By inclusive fitness is meant the tendency of genes to influence their frequency not only through the survival and reproduction of the individual carrying them but also through the survival and reproduction of other closely related individuals who may be carrying the same genes through common descent. This is the concept introduced by Hamilton (1964) to account, using the mathematics of evolutionary genetics, for the existence of altrusim in animals, which previously seemed something to be culled by the process of natural selection. Hence the need for a newly defined subprocess of natural selection, called kin selection. If I die to save my identical twin, then the frequency of any gene that helped predispose me to that action will (all else being equal) be unaffected by my death. In general terms, such genes, or any genes predisposing me to self-sacrifice for a relative, should be favored under conditions where the ratio of the recipient's benefit to the altruist's costs exceeds the inverse of the degree of genetic relatedness. This concept has been invoked to explain self-sacrifice of soldier ants for the colony, alarm calls of birds and ground squirrels, and nepotism in human beings, among many other phenomena of human and animal behavior. Other theories brought to bear on the problem of altruism have been reciprocal altruism and the prisoner's dilemma model of cooperation, neither of which requires that the altruist and the recipient be related.

As argued by Robert Trivers (1972, 1985) from a suggestion of Darwin's, in species with two sexes in which there is a physiological or behavioral difference in the energy invested in individual offspring, the sex that invests more will become the scarce resource over which the other sex competes. In mammals and in most birds, females exhibit greater investment, but direct male parental investment may be very high in some species. Species in which male parental investment is high tend to be those in which pair-formation of a breeding male with the breeding female is long lasting; sexual dimorphism, both morphological and behavioral, is low; male competition for females is low; and variability among males in

reproductive success is low. These "pair-bonding" species, a category including 8,000 species of birds but only a minoirty of mammal species, may be contrasted with "lek" or "tournament" species, so called because they sometimes have annual seasonal breeding "tournaments" in which males compete fiercely for females. These species often have high sexual dimporphism for display or fighting (e.g., antlers or peacock feathers), low tendency for pair formation, low direct male parental investment in offspring, and high variability in reproductive success.

Human beings are considered to be near but not at the pair-bonding extreme of the continuum, as viewed from the perspective of sexual dimorphism, degress of direct male involvement in the care of offspring in a wide range of cultures, and the known distribution of human marriage forms (Daly and Wilson 1983, Murdock 1967). Polygyny, in which one man marries several women, is allowed or encouraged in 83 percent of known cultures in the anthropological record (708 of 849), while the converse arrangement, polyandry, is rare (4 of 849), and a double standard of sexual restriction is extremely common; still, most human marriages have probably been monogamous at least in intent.

A neo-Darwinian model of parent-offspring conflict advanced by Trivers (1974, 1985) has profound implications for the nature of the family. Weaning conflict is very common among mammals, and there are equivalent phenomena among birds, even including tantrum behavior on the part of the weanling. If the evolutionary purposes of mother and offspring were isomorphic, then they should "agree" (the use of this kind of language is shorthand for "should have been selected to act as if they agreed" and implies no conscious intent) that a given level and duration of investment is necessary and sufficient, after which attention should be turned by the mother to her next unborn offspring. A naive model of the nature of the family assumes that since it functions as a harmonious unit under ideal conditions, that is presumably how it was designed by evolution. However, it was not so designed. Like the breeding pair discussed above, it is an association among individuals with overlapping but distinct evolutionary purposes. Its members naturally pursue individual goals that are sometimes at odds with each other's ultimate (not merely temporary) purposes, and their relations are naturally conflictful rather than harmonious. This natural conflict is not the result of friction in what should be or could be a smoothly functioning system but is intrinsic.

Competition among unrelated individuals can be expected at times to be extreme. Virtually all animal species for which there is sufficent evidence have been seen to exhibit extremes of violent conflict, up to and including homicide, in the wild (Wilson 1975). The belief that human beings are rare among animal species in that we kill our own kind is erroneous, and more evidence to the contrary accumulates every year.

One particularly noteworthy phenomenon is competitive infanticide , already alluded to in relation to wild chimpanzees. The paradigmatic case is that of the Hanuman langur moneky of India, as observed by Sarah Blaffer Hrdy (1977), among others. Langur troops consist of a core of related females and their offspring, associated for a period of a few years or less with unrelated immigrant males. Occasionally, new males arrive and challenge the resident males. If they win and take over the troop, they drive the previous males away and proceed systematically to attack and kill resident infants under six months of age. The mothers of those infants then come into estrus again (much sooner than they would have if the infants has survived and continued to nurse) and are impregnated by the new males. Controversy has centered over whether this is normal behavor or a response to crowding or other soical stress. Such controversy misses the point that the behavior enhances the reproductive success of the new males at the expense of the old ones and therefore can be expected to be favored by natural selection, whether or not we choose to call it normal. Furthermore, similar phenomena have now been observed in many species.

The delineation of universal features of human behavior is central to the elucidation of the effects of phylogeny. But natural selection operating on organisms ancestral to ourselves created not only individuals with certain needs, drives, and capacities but also equations—"if-then" statements—relating the environment to the social system, the social system to the individual, and so on. In a cross-cultural study of husband-wife intimacy (Whiting and Whiting 1975), it was hsown that societies in which husbands eat, sleep, and care for children together with their wives are also those that are less belligerent. That is, phylogeny appears to have provided a system such that separating men from women and small children is associated with successful adapation as warriors. This is not to say that they must be warriors or that they must be aloof from their wives but that choosing aloofness may increase effective belligerency and/orperhaps vice versa. The universal characteristic here is not a phenotypic characteristic at all but an underlying mechanism relating two sets of characteristics to each other. (An extended discussion of this conceptual framework may be found in Konner 1982b .)

In the past decade, the application of neo-Darwinian or sociobiological theory to ethnological materials has produced many findings that seem to bypass the complex questions of the relationships among society, cutlure, and individual development. For example, societies in which young men inherit land from their mothers' brothers are more lax about the prevention of female adultery than are societies in which young men inherit from their fathers (Kurland 1979); in societies in which polygyny

is allowed, wealthier and more influential men tend to have more wives (Betzig 1986); and in small-scale societies in which adoption of children it common, it tends to follow patterns predicted by genetic relatedness (Silk 1987). Investigators mkaing these findings usually declare that they do not claim any direct genetic basis for these variations in human behavior, and indeed some of the worst confusion about sociobiology stems from a failure to appreciate this distinction between the propositions of neo-Darwinian theory and those of traditioanl behavioral genetics or molecular genetics.

Even in a nonhuman species such as the red-winged blackbird, males singing on richer territories mate with several females instead of one (Harding and Follett 1979). But the mechanism of this flexible adaptive system—known as a facultative adaptation—must be quite different in blackbirds than the similar mechanism in human beings (although it would probably underestimate blackbirds to assume that in them the system is under tigth genetic control). The wings of insects some from thoracic tissue, the wings of birds from forearm structures,  the wings of bats from fingers, and the wings of humans from technology. These four adaptations to the problem of flight serve similar functions with extremely different provenance. The same will prove to be true of adaptations in social behavior (Konner 1982b ).

Neo-Darwinian or sociobiological theory is sometimes presumed to carry value judgments as a necessary concomitant. This logic appears to suggest that whatever is, is right. An extension of this fallacy would hold that sickle cell anemia and thallasemia must be accepted because natural selection has maintained them through balnced polymorphism, the heterozygotes being at an advantage in malaria resistance; or that myopia should not be corrected because natural selection in favor of sharp vision has relaxed in the human population since the end of the hunting and gathering era. Human judgments about what is desirable are separate from and must take precedence over any observations or explanations of what exists in nature, although they may be enhanced by taking the facts of the natural world into account.

IV

The main enterprise of cultural anthropology has been the description and analysis of cross-cultural variation, but the enterprise has always had an inevitable, even if tacit, complement: the characterization of features of human behavior that do not vary or that vary relatively little. The concept of universals has, howeve,r at least five different meanings: behaviors, such as coordinated bipedal walking or smiling in social greeting, that are exhibited by all normal adult members of every known

society; behaviors that are universal within an age or sex class, such as the refleces in all normal neonates or the ejaculatory motor action pattern in all postpubertal males; population characteristics that apply to all populations but not all individuals, such as the sex difference in physical aggressiveness; universal features of culture rather than of behavior, such as the taboos against incest and homicide, or the highly variable but always present institution of marriage, or the social construction of illness in attempts at healing; and, finally, characteristics that, although unusual or even rare, are found at some low level in every population, such as homicidal violence, thought disorder, depression, suicide, or incest.

The list of characters that fill these five categories is a very long one, much longer than the prominent anthropologists of the early heyday of cross-cultural study would have predicted (Eibl-Eibesfeldt 1988). The search for societies without violence, or without gender differences that go beyond childbearing, or without mental illness, or even without the ability to make and use fire has been a vain one, and although there is convincing documentation of variation in the incidence or context of expression of most human behaviors, the existence of such a large core of constantly present, if variable, features constitutes a demonstration of the reality of human nature and its validity as a scientific construct (Konner 1982b ).

In the realm of psychosocial development, Freud postulated, and present-day child psychiatry continues to accept in altered and disputed forms, a universal sequence of emotional development on which the social environment of the family could be claimed to produce enduring traits of emotional disposition. Beyond some very general elements—the existence of infantile sexuality, the formation of an attachment to a primary caretake who is usually the mother, the ubiquity of conflicts and jealousies within the family—this allegedly universal sequence has never found empirical support; hence the unresolvable disputes among different schools of psychoanalysis and the enduring skepticism of outsiders. Extensive cross-cultural studies of human behavioral and psychological development have not produced evidence relevant to these particular models, but they have produced extensive evidence supporting some more empirically grounded putative universals of psychosocial growth. In the absence of knowledge of neuropsychological development, psychoanalytic theory postulated a libidinal theory of this development (Freud 1920) that few take seriously today. However, the growing body of actual knowledge about neural and neuroendocrine deveopment can now begin to serve a parallel function in relation to the more empirically grounded newer studies of psychosocial growth.

Among the well-established cross-cultural universals of psychosocial development, the following are the best supported and in many cases can

be plausibly related to putative underlying neural events (Konner 1982a , 1991): the emergence of sociality, as heralded by social smiling, during the first four months of life, in parallel with the maturation of basal ganglia and cortical motor circuits; the emergence of strong attachments, as well as of fears of separation and of strangers, in the second half of the first year of life, in parallel with the maturation of the major fiber tracts of the limbic system; the emergence of language during the second year and after, in parallel with the maturation of the thalamic projection to the auditory cortex among other circuits; the emergence of a sex difference in physical aggressiveness in early and middle childhood, with males on the average exceeding females, a consequence in part of prenatal and rogenization of the hypothalamus; and the emergence of adult sexual motivation and functioning in adolescence, in parallel with and following the maturation of the reproductive system at puberty, against the background of the previously mentioned prenatal androgenization of the hypothalamus. In addition, there are a number of apparent cross-cultural universals of cognitive development.

There are other probable cross-cultural developmental universals, such as increased babbing in the second half of the first year and possibly progress through the first three, or perhaps four, of the six stages in Lawrence Kohlberg's scheme of moral development in childhood. Although the underlying neuropsychology is at an early stage of elucidation, the cross-cultural universality of these traits is well established; in each case, there is extensive experimental evidence to support the maturational nature of the process in behavioral development. They constitute a first approximation of the true structural basis of psychosocial development, which Freud groped fro whit his crude theory of libidinal development in the nervous system.

They also constitute a firm basis for the future understanding of how variations in social experience, whether clinical or cross-cultural, act on the maturing psychosocial competence to produce potentially lasting variations. In each of the processes mentioned, cross-cultural differentiation of the maturing competence begins almost as soon as the maturation occurs. However, the acceptance and increasingly detailed and reliable description of the maturational constants underlying the variation in psychosocial growth will provide a steadily firmer place on which to stand while attempting to investigate the role of cultural and individual experience.

V

Within the last two or three years, there has emerged a new mode of inquiry in the study of human nature. The current revolution in mo-

lecular genetics is rapidly leading both to a molecular neurogenetics and to a molecular genetics of behavior and mind. Its established empirical base already extends from the simplest animal systems to the most complex functions of the human mind and from the earliest to the latest stages of the life cycle. Some highlights among its recent discoveries are the following:

1) a family of genes coded for a set of neuropeptides that, in turn, controls the stereotyped egg-laying behavior of the sea slug Aplysia californica (Scheller et al. 1984);

2) a Drosophila behavioral mutant has been explained as the result of known genes that alter the potassium channel of the neuronal membrane (Tanouye et al. 1986);

3) a single-gene form of human pseudohermaphroditism has been traced to deficiency in 5-alpha-reductase, which converts testosterone to dihydrotestosterone; affected individuals have an ambiguous or feminine body habitus and psychological disposition until puberty, when they become physically and psychologically masculine despite having been raised as girls (Imperato-McGinley et al. 1979, 1980);

4) Huntington's disease, a neuropsychiatric condition that presents in the thirties or forties (often beginning with psychiatric manifestations), has been shown to be caused by a dominant gene on the short arm of chromosome 4 (Gusella et al. 1984);

5) manic-depressive illness (bipolar affective disorder), a severe form of mental illness presenting in adulthood, has been shown in different kindreds to be caused in part by a gene on the X chromosome (Baron et al. 1987);

6) Alzheimer's disease, the most common form of late-life dementia, has been shown to be caused in some kindreds by a gene on chromosome 21; a DNA probe cloned from the amyloid protein long known to accumulate in the brains of affected people has been localized to the same chromosome section; and the same gene is duplicated in individuals with Down's syndrome—who develop early Alzheimer's—even in the absence of the usual chromosomal anomaly, a duplication of the whole chromosome (Tanzi et al. 1987; St. George-Hyslop et al. 1987; Goldgaber et al. 1987; Delabar et al. 1987).

These recent findigns remove any doubt regarding the ability of genes to alter complex behavior through comprehensible biochemical pathways affecting the nervous system. They are not subject to any of the methodological criticisms always leveled at classical Mendelian behavioral genetics, especially at correlational human studies. Extreme skeptics will still claim that these findings have no bearing on the development of normal human behavior, but there is no reason to believe that they are right. On the contrary, it is likely that of the hundred thousand

or so genes in the human genome, the ones most easily identified would be the ones with the most devastating effects and that subsequently it would become possible to identify genes affecting physiology and behavior within the normal range. We can expect such identifications within one or two decades.

Such findings, however, are not the end but the beginning of the development of the epigenetic—interactionist—approach to human nature. In the absence of other treatments, few would argue that we should refrain from "gene surgery" for Alzheimer's disease, but even with manic-depressive illness there will be serious ethical issues in tampering with the system, which may produce certain desirable personality variations and even exceptional creativity as well as serious mental illness. Within the normal range, the arguments for restraint would be even stronger. Nevertheless, from the viewpoint of analysis of the development of behavior, a technology of molecular genetics will provide insights that will transform our view of human nature. Already we have learned that both cognitive and emotional functions can be altered by specific genes and that genes can manifest themselves in the behavioral phenotype at almost any stage of life, sometimes without prior developmental manifestations of any kind. The question is, How will the environment prove to interact with genetic predispositions and vulnerabilities?

Phenylketonuria provides a valuable model, It is a simle genetic disorder with increasingly understood molecular genetics, yet with an environmental proximate cause and a solution hat involves modification of one of the most mundane features of the environment, the diet. Such environmental modification essentially obviates the impact of the genotype. Drug treatments have also bee tried, and in the not too distant future, a molecular genetic intervention in the germ line ("gene surgery") may be possible. At that point, there will be a full spectrum of treatment possibilities, making phenylketonuria a paradigmatic instance of the complex interactions of genotype, metabolism, and environment in the development of neural, behavioral, and mental phenomena. It is not difficult to imagine in broad outline the similar range of interpretations that will develop for a variety of other abnormalities of brain and behavior and indeed for some variations within the normal range.

In addition, there are likely to be many new discoveries about the way environment exerts its influence on the development of behavior, and some of these are likely to be surprising. Neuroembryological research has given new meaning to the concept of plasticity by showing the great importance of competition among neurons and connections for destination sites in the developing brain, and the process of selective pruning goes on postnatally as well as prenatally (Changeux 1985; GoldmanRakic et al. 1983). Brain functions as crucial to psychology as laterality

may depend on complex intrauterine mechanisms under indirect, rather than direct, genetic control (Geschwind and Galaburda 1987), and these mechanisms of plasticity were not only unexplored but unsuspected until a few years ago.

VI

In the eithteenth century, Goethe (Magnus 1949) posited the existence of a fundamental or archetypal form in plant life, a sort of key to the order of life itself in the largest sense, and perhaps even of the universe beyond the realm of the living. Indeed, he made his search for order a foil to that of Newton, which he considered too mechanical; he thought that even the fundamental ordering principles of the universe might be biological, not physical. Although in this he went too far, there is a sense in which the Urpflanze , Goethe's ultimate plant form, really does exist and in which it has become, two centuries after he posited it, as central to the enterprise of at least the life sciences as he believed it would be.

The Urpflanze is, of course, DNA, and with the scientific unraveling of its form has come, and will continue to come, a sense of order and power in the realm of biology that only a mind like Goethe's could have imagined. The extent to which the realm of behavior will also come under the sway of this intellectual order remains to be seen; but even the answer to this question will be largely provided by that order. Undoubtedly, the answer will involve mechanisms of epigenesis that include such phenomena as operant conditioning, snesitive periods, psychological trauma, cognitive maps, and symbol systems as well as diet, infection, and injury. But the way these phenomena operate—within the constraints provided by the human genome—to produce individual and collective behavioral patterns and tendencies is vastly more uncertain than the textbooks in the relevant fields allow, and the mutual contradictions of those textbooks underscore the uncertainties. That the delineation of how the environment affects the individual, beyond the hoary pieties of plasticity, remains a task almost completely for the future is perhaps the greatest discovery of the past twenty years.

Two further implications of recent advances in biology need to be emphasized. First, if neo-Darwinian principles of behavior and reproduction are even mostly correct, the fundamental metaphor of modern social science is in error. That metaphor, which is as venerable as social science itself, claims that society is an organism, with individuals as cells, specialized subgroups of individuals as tissues or organs, and conflict as a transient aberration, or pahtology, the elimination of which restores the social organsm to health. The basic weakness of the analogy is most starkly exposed each time an individual or group departs from the soci-

ety and joins or forms another—something the cells or organs of an animal cannot do, of course—but in fact the weakness is evident in the ubiquity of social conflict even within the most intimately interdependent social relationships. Such conflict is not inadvertent friction in a system that should, by design, function smoothly but is an inherent and inevitable expression of the purposes of social life itself.

Second, the motivational portions of the brain, particularly the hypothalamus, have functional characteristics relevant to the apparent chronicity of human dissatisfaction. Animal experiments on the lateral hypothalamus suggest that the motivated condition is to some extent nonspecific, with the internal state responsive to but not geared for the particular external circumstances. A continuum between attentiveness or alertness and intense drive states ensures that responsiveness will never be long delayed but also that it will not always be appropriate and, more important, that the organisms's chronic internal state will be a vague mixture of anxiety and desire—best described perhaps by the phrase "I want," spoken iwth or without an object for the verb. This insight of physiological psychology about the internal motivational states of animals like ourselves fits well with the more recent insights of sociobiology about the conflictful external relations entered upon by the same and similar animals and also with the failure of the organismal model of societal coherence.

One consequence of these insights is that the view of life current in behavioral biology bears more resemblance to the view taken in the time-honored traditions of the humanities than either does to the canons of social science. Henry James once described life as "slow advance into enemy territory" and wrote, "Life is , in fact, a battle, Evil is insolent and strong; beauty enchanting, but rare; goodness very apt to be weak; folly very apt to be defiant; wickedness to carry the day; imbeciles to be in great places, people of sense in small, and mankind generally unhappy" (Zeibel 1951). Similar sentiments have been common in the literary traditions of many societies from the earliest religious and epic sagas to novels and plays completed this morning. Religious traditions of varied character recognize the reality of a deeply, even tragically, flawed human nature, but they exhort against it, while literary artists seem satisfied to describe it. In either case, it is viewed, sadly, as all too real, and these vividly brilliant clasic observations of it fit well with Darwin's remark to Joseph Hooker: "What a book, a Devil's Chaplain might write on the clumsy, wasteful, blundering low and horribly cruel works of nature!"

Of course, that nature also includes an equally inherent ethical component that derives from the necessity for cooperation and altruism, the potential for responsibility, decency, love, even happiness. These capacities, too, are shared by amny other animals, and we can take encouragement from the fact that they are so widespread in nature. But for them

to prevail requires the kind of collective attention that is possible only in the framework of human culture. In this framework, reflection on the outcomes of natural tendencies results in judgments that restrain or modify those tendencies. It is full of deceptions, but it is much better than nothing, and it exceeds the capabilities of any other animal for similar restraint and modification.

The evolutionary, biological view of human nature provides many parallels with that of animal natures and only a few clear distinctions. Traditionally and presently, distinctions between ourselves and animals have emphasized the primacy and complexity of human rational faculties. But in recent years, the development of artificial intelligence has duplicated a surprising number of those same faculties, and in the community of people who think about the implications of this fact, it is common to distinguish humans from hacines by referring to the human emotional faculties—precisely those we share in common with animals. It would seem that we are sorted to a pulp, caught in a vise made, on the one side, fo the increasing power of evolutionary biology in explaining the emotions and, on the other, of the relentless duplication of human mental faculties by increasingly suble and complex machines. So, what is left of us?

What is left is that only we combine the emotions and the life cycle drama of the animal world with a fully empowered reflective and communicative faculty. No other animal has that faculty, and no machine has an animal bodily life. Other animals can communicate, but they do not exchange views on the rightness or wrongness of their emotions. Machines can network and think, but they cannot discuss their fear of dying. What religious people think of as the soul or spirit can perhaps be fairly said to consist of just this: the intelligence of an advanced machine in the mortal brain and body of an animal. And what we call culture is a collective way of using that intelligence to express and modify the emotions of that brain, the impulse and pain and exhibaration of that body. Both the intelligence and the impulse, the communicative capability and the pain, are components of human nature, and the wy they interact is the unique feature of that nature. Without conceding the existence of human nature, without describing it as forthrightly and richly as possible, we will never fully exercise that crucial feature, which alone holds the prospect of an admittedly limited but absolutely imperative transcendence.

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