Social DNA. M. Kay Martin

entitled “The Egg and the Sperm: How Science Has Constructed a Romance Based on Stereotypical Male-Female Roles.” Its focus is on how male and female behavioral stereotypes have become infused into the imagery of conception. How could the description of a relatively straightforward biological process be influenced by cultural bias? Martin’s paper calls attention to the findings of a Johns Hopkins University study that fundamentally revised the science on how fertilization actually occurs. Whereas it was formerly thought that sperm were the aggressors that burrowed through the egg’s zona by the force of their tails, the study discovered that eggs actually capture sperm cells, adhering to them firmly and forcing the head of the sperm to lie flat against the surface of the zona. Successful conception requires a unique and active partnership between the gametes:

      The trapped sperm continues to wiggle ineffectually side to side. The mechanical force of its tail is so weak that a sperm cannot break even one chemical bond. This is where the digestive enzymes released by the sperm come in. If they start to soften the zona just at the tip of the sperm and the sides remain stuck, then the weak, flailing sperm can get oriented in the right direction and make it through the zona—provided that its bonds to the zona dissolve as it moves in. (Martin 1991: 493)

      Martin’s point is that even in the seemingly objective context of reproductive physiology, biological facts can be construed in cultural terms. Thus, female gametes have been typically characterized as slow-moving, passive, dependent cells waiting to be “deflowered” and seeded with life, while male gametes are aggressive, active, and competitive cells bent on forceful penetration of the hapless egg. The fact that eggs play a very active and complementary role in facilitating fertilization by trapping sperm cells and preventing their escape—that eggs and sperm are mutually active partners in the business of conception—was an idea unexplored by biologists for decades. Instead, eggs and sperm in scientific discourse took on the idealized personalities of females and males in the larger society.¹

      Reproductive Roles and Social Origins Theory

      Before the development of modern genetic science, theorists speculating on the evolution of early human sociality relied principally on observations of animal reproductive behavior, along with conclusions drawn from their own cultural experience (including sacred creation myths). The prevailing Victorian viewpoint was that perceived differences in male-female sexuality were linked to innate behavioral traits. Males were naturally sexual, aggressive, competitive, and cognitively superior. Females, in contrast, were both defined and limited by their maternal reproductive functions. As such, they were typically characterized as naturally asexual, passive, nurturing, noncompetitive, and also less capable of complex thought. Several nineteenth-century scholars proposed that these disparate male and female traits had consequences for the way that human society evolved. The abbreviated version of such theories is that, thanks to the alleged sexual restraint of women, early humans emerged from an original state of promiscuity to one of ancient matriarchy, in which society was organized around the obvious biological linkage between females and their offspring. This evolutionary stage was eventually overthrown by males, who established domestic units and enjoyed sociopolitical dominance from that point forward.²

      Hindsight being 20/20, such notions about innate male and female aptitudes and universal evolutionary stages are now typically dismissed as examples of both gender stereotyping and immature science. But as with the story of the egg and the sperm, cultural bias continues to color our perception of human nature and societal origins. Although presented with a different veneer, behavioral stereotypes rooted in the perceived consequences of anisogamy have been amazingly persistent. International conferences and symposia held in the late 1950s and 1960s framed a model of ancient Paleolithic social life that equated the advent of hunting by males with the origin of human culture itself. As in Victorian times, males were portrayed as sexually dominant and competitive, but as presumably bridling this enthusiasm for the camaraderie of the hunt. This model assigned males active roles as family heads and providers to dependent consorts and offspring, and credited them with the defining achievements in human evolution, such as the invention of tool making.³ Females, in contrast, were cast in a largely peripheral role, serving as reproductive vessels and performing perfunctory domestic tasks of limited economic value. They were, in essence, silent partners in the evolutionary saga—dependents and nonproducers who traded sexual favors and reproductive functions for economic support.⁴

      A subsequent spin-off of this model, the male-bonding hypothesis, gained some popularity in the early 1970s.⁵ Its basic thesis was that males are biologically predisposed toward cooperative activities, whereas females lack such built-in genetic codes. Proponents argued that this sexual divide originated from selective pressures that favored bonding among males, initially for group defense and eventually for the predation of the hunt. The model went further, linking such activities to cortical expansion in ancient humans—a consequence of subordinating male sexual competition to the interpersonal cooperation and emotional control necessitated by cooperative hunting. Opportunities for social and intellectual advancement provided by the hunt were allegedly unavailable to the other half of the species due to their reproductive responsibilities and assumed temperament. Females, allegedly burdened by serial pregnancies, inferior physical and cognitive abilities, and swings in “emotional tonus,” were not only presumed unfit for the hunt, but to pose a disruptive influence by stimulating male competition for sex. On this basis, the theory concluded that natural selection has favored females who acquiesce to their basic reproductive and domestic roles.

      A new chapter on theories of human social origins was introduced in 1975 with the publication of E. O. Wilson’s Sociobiology. The sociobiology movement spurred significant new scientific research that has led to a re-examination of assumptions about the evolutionary consequences of human anisogamy. Unanimity of opinion among its followers, however, has been elusive.⁶ One sociobiological perspective, exemplified by the selfish-gene theory, is that the disparate reproductive strategies of the sexes are inherently conflicting and are played out in an atmosphere of male self-interest, parasitism, and deceit. Other sociobiological theories, in contrast, recognize differences in male-female reproductive strategies but seek to understand how the fitness of both sexes and that of group members is facilitated through the evolution of social behaviors based on cooperative, reciprocal relationships. These contrasting viewpoints are briefly outlined here, and their relevance for theories on human family origins are explored more fully in the next two chapters.

      Exploitation and Parasitism

      Perhaps the most well-known work linking anisogamy to male social dominance is Dawkins’s The Selfish Gene (1976). It advances the notion that genes tailor their replication strategies to fit the bodies in which they find themselves and that these opportunities differ for male and female bodies. For Dawkins, it all comes down to anisogamy—all social differences between the sexes can be traced to the fact that sperm cells are smaller and more numerous than eggs:

      Sperms and eggs . . . contribute equal numbers of genes, but eggs contribute far more in the way of food reserves: indeed, sperms make no contribution at all and are simply concerned with transporting their genes as fast as possible to an egg. At the moment of conception, therefore, the father has invested less than his fair share (i.e. 50 percent) of resources in the offspring. Since each sperm is so tiny, a male can afford to make many millions of them every day. This means that he is potentially able to beget a very large number of children in a very short period of time, using different females. This therefore places a limit on the number of children a female can have, but the number of children a male can have is virtually unlimited. Female exploitation begins here. (Dawkins 1976: 141–42, emphasis added)

      The theory is that each reproductive partner has the goal of maximizing the number of their surviving offspring, but that females are at a disadvantage due to their greater parental investment. According to Dawkins, two principal “counter-ploys” may be pursued by females to reduce their exploitation by males. The first, dubbed the “domestic-bliss” strategy, envisions females as feigning “coyness” in order to assess potential mates in advance for favorable attributes (i.e., fidelity and domestic assistance) and to demand material investments prior to copulation. The second is referred to as