Humanizing Sociological Theory With a New Science of Human Nature
If, as believed for so long by those who subscribed to the Standard Social Science Model of human behavior, humans are devoid of an evolved psychology' that represents anything beyond the much-celebrated and extraordinarily powerful ability to learn and the “capacity for culture,” then sociology’s almost studied disinterest in the biology' of the human brain and how it evolved would be both understandable and excusable. However, over 45 years of developments in evolutionary behavioral biology no longer make that position tenable. Instead, it is difficult to imagine that sociologists will allow what has been called “biophobia” and “bioilliteracy” (Machalek and Martin 2015) to continue to isolate them from rapidly developing bodies of knowledge in sociobiology, behavioral ecology, and evolutionary psychology, as well as comparable developments occurring among practitioners of the “new evolutionary sociology.”
The “search for human nature,” as Turner and Machalek describe it (2018: 309—336), has endured as an almost timeless pursuit that long preceded the emergence of sociology. Today’s evolutionary social and behavioral scientists typically adopt one of two approaches in efforts to specify the properties of Homo sapiens' evolved psychology'. The first, largely inductive, approach entails examining empirical patterns of behavior and then offering inferences about features of an evolved psychology that could have produced them. The second, deductive, approach uses as its point of departure the theory of organic evolution by natural selection (and/or derivative theories, such as sexual selection or the theory of parental investment) in attempting to deduce the properties of evolved human psychology. As discussed earlier, Turners (2000) and Turners and Maryanski’s (2008) work on how hominins underwent an evolutionary transition from being an individualistic, weak-social-tie to a more highly social, high-solidarity ape provides a good example of the first approach. By comparing humans to the great apes, Turner and Maryanski were able to identify components of the psychological nature that humans inherited from the LCA by making inferences derived from empirical patterns of ape social organization and features of the human brain itself. In their view, the most significant of such features is the human brain’s highly enhanced emotional capabilities. In fact, contrary to the all-too-often-embraced assumption that emotionality and rationality are at odds with each other, Turner explains that the evolution of human emotional capabilities was a necessary precursor for the evolution of advanced cognition, and rationality, among humans (Turner 2018). Absent significant neurological support for emotions, the rise of cognitive abilities and human intelligence that can support the eventual development of culture, including cognitive culture, is simply not possible (Maryanski and Turner 2018: 121-126).
The search for evolved behavioral propensities that constitute human nature is gaining momentum. To date, it has yielded evidence about diverse aspects of human behavior such as the following: (1) behavioral propensities that both enable and inhibit the expression of violence in situations that involve “Darwinian conflicts of interest” (Daly and Wilson 1988); (2) capabilities for reasoning about and responding to situations entailing reciprocity' and exchange and scenarios where norms of reciprocity' are violated (Cos- mides 1989; Cosmides and Tooby 1992; de Waal 1989, 1991, 1996); (3) an evolved propensity' to develop religious cognitions and engage in religious behavior (Maryanski and Turner 2018; Turner et al. 2018); (4) the capacity' to reason about both archaic, universal adaptive problems as well as about new, unprecedented adaptive problems that arise in novel environmental circumstances (Kanazawa 2004); (5) evolved propensities that are implicated in dominance contests and the pursuit of social status (Hopcroft 2006, 2009a, 2009b; Mazur 2005, 2015; Nielsen 2018); and (6) an evolved propensity to invest differentially' in male versus female offspring under variable environmental conditions, as predicted by the Trivers-Willard hypothesis in evolutionary biology' (Hopcroft 2005).
Evolutionary' thinking makes clear that behaviors that are most salient to survival and reproduction are those that are most likely to feature evolved adaptations for coping with universal challenges confronted by humans. Though survival is a precondition for reproduction (and thus organic evolution), survival that fails to yield reproductive success does not produce evolved adaptations. Thus, behaviors with a direct bearing on reproduction represent an optimal area of inquiry for researchers trying to identify evolved properties of human nature. In that regard, the early work on human sexuality by the evolutionary anthropologist Donald Symons has been identified as pioneering and path-breaking by the evolutionary psychologist David Buss, who described Symons’s work as the “first major treatise on evolutionary psychology proper, highlighting the centrality of psychological mechanisms as adaptations, and using human sexuality as a detailed vehicle for this more general argument” (2016: 287). By the 1990s, human mating had become the “most studied domain of evolutionary psychology” (Buss 2016: 280). Reviewing a sample of some of this work enables us to identify potential behavioral propensities that may be operative in helping shape male-female relations in contemporary societies.2
Natural selection affects the health and survival prospects of organisms. Sexual selection affects the reproductive prospects of organisms, and the two forms of selection can sometimes work at cross “purposes.” For example, it has been well documented that bright plumage among males in some bird species is attractive to prospective female mates. In evolutionary terms, “female choice” among these birds favors bright plumage in males, and the underlying selective advantage appears to be that bright plumage is an indicator of a robust immune system. Accordingly, female birds that choose brightly colored males as mates may be conferring adaptive benefits to their offspring. The classic example of this dynamic is the brilliant, even gaudy, plumage of the peacocks tail. A robust immune system benefits the peacock himself, and the bright coloration of his plumage advertises the quality of that immune system, thereby making him an attractive potential mating partner. However, the same plumage that is favored by peahens also can attract predators that cue on bright coloration. Thus, the Darwinian adaptive “problem” confronted by the peacock is to succeed in attracting females but, simultaneously, avoid attracting predators. In this case, the forces of natural and social selection work in some degree of opposition to each other.
Sexual selection occurs in response to three Darwinian adaptive problems confronted by all sexually reproducing organisms: (1) finding a mate (reproductive partner), (2) retaining a mate if reproduction requires more than one mating episode, and (3) providing parental care in species with altricial offspring.3 In evolutionary terms, prospective reproductive partners represent what evolutionary biologists describe as one of two types of resource value to each other: reproductive value versus somatic value. Reproductive value refers basically to the “quality” of genes and the traits they produce that each partner brings to the reproductive relationship. Quality is conceptualized as the value of genes in producing offspring that are healthy and themselves bear the promise of good reproductive prospects. Somatic value refers to the ability of a reproductive partner to bring other kinds of resources such as food, nests, protection, and parental care to the reproductive partnership. Accordingly, sexual selection theory predicts that organisms will evolve mechanisms for assessing both the potential reproductive value and somatic value of prospective reproductive partners. Based on such assessment processes, each prospective partner “chooses” a specific individual as a mate, albeit rarely consciously. Instead, prospective mates can be expected to have evolved assessment mechanisms of which neither mate is likely to be aware. That is, prospective mates rely upon “cues” in order to assess mate value, and such cues are unlikely to be the object of their awareness.
A good example of such a cue is “fluctuating asymmetry,” or the extent to which certain features of an individual’s morphology are bilaterally symmetrical. A considerable body of research has adduced evidence that bilateral symmetry often plays a significant role in determining attractiveness or beauty. A surprisingly large body of research has supported the hypothesis that by attending to the degree to which peoples features exhibit bilateral symmetry in traits such as eye orbit, individuals will glean information about developmental stability in response to environmentally induced stress. Thus, by perceiving as more attractive individuals with highly symmetrical features, a male or female assessing mate quality is gleaning information about certain important determinants of health, survival, and reproductive prospects (Turner and Machalek 2018: 227)
Though the biology of sexual reproduction requires males and females to cooperate in their reproductive venture, their fitness interests overlap but do not coincide. Because of sex-based morphological and physiological differences in the division of reproductive labor, males and females routinely find themselves at odds with respect to some aspects of mate selection, mate retention, and parenting. Accordingly, average differences between male and female minds are to be expected in the form of adaptations that reflect fitness “interests” that not only may fail to overlap, much less coincide, but instead are incommensurate with each other. As a result, we should expect to find both similarities and differences between males and females in their mate preferences. These will be identified and discussed as we review a few possible candidates for evolved mental adaptations among human males and females in relation to mating and reproduction.
Before reviewing sex differences in mate preference, research reveals that some qualities in prospective mates are preferred by both sexes. Based on his analysis of 37 cultures, Buss and his colleagues have identified 18 traits identified by both males and females as desirable in a mate, and the top four rank identically as (1) mutual attraction-love, (2) dependability of character, (3) emotional stability and maturity, and (4) a pleasing disposition (Buss in Hopcroft 2016). In fact, nine of the top ten traits identified as desirable by both males and females are identical, though they are not ranked identically. The coincidence of the top four traits is not surprising, however, because they can be interpreted as indicators of favorable prospects for stability in a mate relationship, thereby yielding not only reproductive (genetic) value to both partners but a likelihood of significant parental investment, a very valuable asset when raising highly altricial offspring such as humans.
Because the biology of reproduction in humans involves asymmetries ranging from the (1) difference gamete size and value (eggs are relatively few in number and metabolically expensive; sperm are plentiful and metaboli- cally relatively cheap in relation to eggs) to (2) the disproportionately greater biological burden born by females during both pregnancy and, in premodern environments, nursing (Huber 2007) to (3) the contrast between maternity confidence always experienced by females versus paternity uncertainty often experienced by males, evolutionary thinking predicts male-female differences in mate preferences. A few of these are reviewed briefly subsequently.
What Can Females Be Expected to Prefer in a Prospective Mate, and Why?
From a female point of view, the Darwinian (reproductive, fitness) value of a male is a function of both the quality of genes that he can contribute to her offspring and the quality, quantity, and reliability of the parental investment he can provide in support of her offspring. Thus, the evolutionary theory of sexual selection predicts that females should express clear preferences for some types of males over others. A significant, and growing, body of empirical research provides evidence about clear preferences that females express for mates.4 In that males can provide both fitness-enhancing genes and somatic resources to the female in support of her fitness interests, it is not surprising to learn that a large and growing body of empirical research reveals that females prefer males with the following qualities: higher social status, economic resources and favorable prospects for financial success, maturity, evidence of ambition, and evidence of dependability and stability (Buss 2016: 105-114; Schmitt 2016: 297-298).
Regarding the physical attributes they prefer in males, females express preferences for height and athletic ability, strength, bilateral symmetry, and physical cues seen as indicating masculinity (Buss 2016: 114—118). Seen from an evolutionary perspective, these cues can be interpreted as helping females identify males with genes that confer both good health and promise for helping support their offspring. A male’s abilities to provide for and protect offspring appear evident in females’ preferences for male kindness and generosity, his ability to express love and commitment to others, and his willingness to devote time and other resources in caring for children (Buss 2016: 118-122; Ellis 1992; Feingold 1992; Schmitt 2016: 297-298).
What Can Males Be Expected to Prefer in a Prospective Mate, and Why?
The asymmetry in gamete numbers and metabolic value (called anisogamy by biologists) would seem to imply that, in contrast to females, a male who mated indiscriminately with every female available to him would be adopting a fitness-maximizing reproductive strategy. While an individual human female produces about 400 ovulated eggs over the course of her lifetime, a male can produce 12 million sperm per hour. The maximum number of offspring produced by a man has been over 1,000. In contrast, a Russian peasant woman is said to have given birth to 67 surviving children. Given this asymmetry between males and females in terms of potential offspring they can produce over a lifetime, it would seem that the only constraint on male fitness is access to female reproductive partners, and thus, males would adopt a mating strategy of indiscriminate, opportunistic promiscuity. However, evolutionary biologists explain that is not the case.
Two sets of constraints appear to be at work that inhibit, among most males, the adoption of indiscriminate promiscuity' as a male mating strategy. First, though less metabolically “expensive" to produce than are eggs, sperm production is still costly. A phenomenon biologists call (unconscious) “prudent sperm allocation” operates in a number of species, including humans (Shackelford et al. 2016). A male sensitivity' to various auditory, chemosen- sory, tactile, and visual cues operates to enable males to adjust the allocation of sperm during copulation (Shackelford et al. 2016: 428). This suggests that while sperm are plentiful, it may not be adaptive for males to allocate them indiscriminately during every mating episode.5
The second set of constraints that inhibit indiscriminate male promiscuity as an adaptive mating strategy pertains to the parental investment that males can provide for offspring. Among highly altricial species like humans, males can provide significant support for offspring, thereby increasing their own fitness by helping raise healthy offspring which, in turn, can survive and prosper so as to produce offspring of their own. Thus, by acting more like “dads" than like “cads,” as evolutionary biologists casually put it, natural selection would favor male reproductive strategies that involve males’ providing parental investment from which their offspring could benefit.
Like females, males can be expected to express mating preferences for reproductive partners that indicate enhanced fitness prospects. For males, this means sensitivity to cues in females that signal good health and fertility. Over 40 years of research, including cross-cultural studies, have revealed male preferences for the following traits in prospective female mates: skin quality'; hair quality; facial symmetry; specific patterns of fat distribution on the body; and certain features of body' shape, especially waist-to-hip ratio (Buss 2016; Sugiyama 2016: 329-331, 353). All of these cues are said to be correlated with overall health and fertility, though, as Sugiyama reports, the salience of these cues varies by the degree to which the environments in which mate preferences are exercised are stressful (2016: 345—350).
In addition to male preferences for female physical traits that signal health and fertility, a second set of cues, largely behavioral, are important putatively by enabling males to assess mate fidelity', thereby addressing the male’s adaptive problem of paternity uncertainty. Paternity uncertainty is, for males, a serious enough perceived threat that researchers have reported a hypersensitivity to infidelity that is much greater among males than females, and it has been characterized as an “infidelity overperception bias” (Andrews et al. 2008; Buss 2016; Goetz and Causey 2009). Even if a female makes a “poor choice” of a mate in terms of the fitness returns she derives by mating with him, she will, at minimum, receive a 50% return on her “fitness investment” even if her mating partner turns out to have delivered suboptimal (in fitness terms) genes and provides little or no parental investment. If, however, a male makes a poor choice in a reproductive partner, is cuckolded, and provides parental investment to offspring that are not his, his fitness returns are zero, and he also may incur opportunity costs by having failed to secure as a reproductive partner a female who would provide him with his own offspring.
It is not surprising then, that although both females and males express sexual jealously toward mates, evolutionary reasoning counsels that such jealousy is a response to very different fitness “threats” represented by sexual infidelity. For a female victimized by male infidelity, the resources lost are somatic, in the form of material resources that could support her offspring, and parental investment by the male, who could provide labor in caring for and raising her offspring. For a male, however, the resource threat comes in the form of allocating his parental investment to offspring that are not his. In fact, differences in the evolved psychology' of male and female jealously have been the subject of research by evolutionary psychologists, and their findings suggest that females are more likely to experience “emotional jealousy,” because a deficit of emotional commitment by a male can pose a threat to the stability of the mating bond, possibly resulting in male abandonment and the formation of a new bond with a different female to whose offspring the male diverts resources. For males, however, jealously is aroused more directly by sexual infidelity per se, because a child that is the product of an “extra pair copulation” (a sexual affair) deprives the male of any “fitness returns” from the relationship and can result in the diversion of somatic resources to offspring that are not his own.
It is important, once again, to emphasize that none of these determinants of how and when to allocate fitness-relevant resources ranging from gametes to trust funds require either males or females to pursue their lifetime fitness “returns” as conscious, goal-directed behaviors. They need only possess an evolved psychology that sensitizes them to fitness-relevant cues in potential mates, remaining all the while oblivious to the fact that they are acting in a manner that can have an impact on their lifetime fitness. All sexually reproducing species are the product of selection forces that maximize survival and reproductive prospects, but neither humans nor other animals routinely, if ever, navigate their interpersonal relationships consciously motivated by the lifetime “fitness returns" that are likely to flow from those relationships. Simply put, natural selection designs males and females to behave as if they were making deliberate, overtly strategic efforts to maximize their lifetime Darwinian fitness (number of surviving offspring produced), when, in fact, almost no human ever behaves in such a manner.
Though interesting and important, it is not possible to review here in any detail evolved behavioral strategies for mate retention, another category of mating behavior that provides evidence of being regulated by evolved behavioral propensities. As Crippen (2015: 402—421) has noted recently, the human mate pair bond is fragile and tenuous. Once established, there is no guarantee that a pair bond will endure. Put differently, having selected a mating partner for a long-term mating relationship, retaining that mate then becomes the next Darwinian challenge confronted by both males and females. Both males and females adopt tactics for mate retention, and both sexes appear to have evolved behavioral strategies that can be directed toward mates themselves or toward potential competitors who threaten to usurp a mate once selected. A brief review of male versus female mate retention strategies is available in Turner and Machalek (2018: 228—234).
This brief review of behavioral propensities pertaining to human mating illustrates what scholars and scientists like Hopcroft mean by “the evolved actor” (2009b). In stark contrast to the tabula rasa model of the human brain and mind, the notion of the evolved actor represents a view of human nature that could not have been imagined by Homans or most of his peers in 1964 when he exhorted sociologists to “bring men back in.” Coincidentally, 1964 was the same year that William D. Hamilton published his classic article on the “genetical theory of social behavior,” which specified the logic for interpreting social behavior as a genetically based, fitness-enhancing phenotypical trait (Hamilton 1964). Only two years later, George C. Williams published what is now a classic in evolutionary biology, Adaptation and Natural Selection: A Critique of Some Current Thought (Williams 1966). Hamilton’s and Williams’ contributions are now regarded as seminal and foundational for the subsequent development of sociobiology and various derivative disciplines such as evolutionary anthropology, evolutionary economics, evolutionary psychology', and evolutionary sociology, among others. The promise offered by the development of these and related disciplines for providing the contemporary behavioral and social sciences, for the first time, with a systematic, scientifically grounded theory of human nature on which to base scholarship and research cannot be emphasized enough. This chapter concludes with a few observations about what it could mean, henceforth, to “bring, for the first time, the evolved actor into sociology.”