Satoshi Kanazawa & Joanne Savage, 2009, Journal of Social, Evolutionary, and Cultural Psychology.
Abstract: There is no consensus on what social capital is because there is no widely accepted theory of values. Capital is a resource that helps individuals achieve some goal, so one needs to know what humans seek to achieve before one can define what capital is (social or otherwise). Evolutionary psychology is a strong contender for a general theory of values. From this perspective, social capital is any resource that inheres in relationships between individuals that help them attain reproductive success. An evolutionary psychological perspective on social capital can solve some empirical puzzles: Why women have more kin in their personal networks than men do; why black women are more likely to have children out of wedlock; why social capital often has opposite effects on status attainment of men and women; and why social capital appears to be declining in the US. An evolutionary psychological perspective can tell us what exactly social capital is, why humans are social and social capital is important to them, when and where humans maintain social relationships, and how to measure social capital precisely.
Social capital is a central concept in rational choice theory (Burt, 2004; Coleman, 1988; Cook, 2001; Sanders & Nee, 1996) and is also the new buzz word in the social sciences. The International Bibliography of the Social Sciences culls 3,774 items with the keyword “social capital” just since 2001 (as of March 2008). In contrast, in the same time period, there are 3,835 items under the much older concept of “human capital,” and only 168 items under “physical capital.” There have been dozens of both academic and popular books published on the topic of social capital in the same time period.
Social capital is unusual as a research topic, however, in that there appears to be no clear consensus among those who write about it as to what exactly it is. Experts have written entire articles defining it (Lin, 2000; Portes, 2000), and many empirical studies on social capital contain sections called “Social Capital” or “What is Social Capital?” (Coleman, 1988, pp. S97-S100; McNeal, 1999, pp. 119-120; Paxton, 1999, pp. 91-97; 2002, p. 256; Renzulli, Aldrich, & Moody, 2000, pp. 524-530; Schiff, 1992, pp. 159-161). It is difficult to imagine a microeconomic article with a section called “What is unemployment?” or a macroeconomic article with one called “What is inflation?” Paxton (1999, p. 90) astutely observes that “the term “social capital” is used in many recent articles but in vastly different ways.” Nobody seems to know or agree on what exactly social capital is.
Why should this be the case? Capital is any resource that helps individuals produce or achieve some goal. Social capital inheres in relationships between individuals, just as physical capital inheres in physical objects and human capital inheres in humans. Thus social capital is any resource that inheres in relationships between individuals that help them produce or achieve some goal. But produce what? Achieve what goal? What are individuals’ goals? What do humans want?
Any resource can be capital depending upon the goal. If your goal is to run an efficient drugs market in your neighborhood, then guns and ammunitions are important physical capital, the ability to distinguish between high-quality and low-quality drugs is important human capital, and connections to corrupt cops in the precinct are important social capital. None of these resources qualify as capital if your goal is to earn an MBA in Harvard Business School. We need to know what the human goals are before we can define what resources qualify as capital. If we don’t know what the goals of human behavior are, we don’t know what social capital is. And if we don’t know what it is, we can’t measure it precisely.
The problem of defining social capital is therefore largely a problem of values. We need a theory of values that explains what humans want in order to define what social capital is. Without it, any definition of social capital is doomed to be ad hoc. There is presently no general theory of values that is widely accepted (Hechter, 1992, 1994; Hechter, Nadel, & Michod, 1993), and economists consider the question of values “out of bounds” (Stigler & Becker, 1977). This is why nobody knows what social capital is, or different people define it differently.
Evolutionary psychology is a strong contender for a general theory of values (Ben-Ner & Putterman, 2000; Horne, 2004; Kanazawa, 2001a). It is a general theoretical perspective that can explain the ultimate (as opposed to the proximate) causes of human behavior, cognition, preferences and emotions. Evolutionary psychology can therefore theoretically define human goals, and thus social (as well as physical and human) capital. Evolutionary psychology concerns ultimate, not proximate, goals of humans, and, as such, is compatible with various proximate theories of values and goals.
In this paper, we present an evolutionary psychological perspective on social capital. We provide the most ultimate theoretical definition and most theoretically driven measures of the concept. We then demonstrate that an evolutionary psychological perspective can solve several empirical puzzles regarding social capital, such as why women have more ties to their families than men do, why black women are more likely to have children out of wedlock, why social capital sometimes seems to have the opposite effects on status attainment of men and women, and why, by some accounts (Putnam, 1995), social capital appears to be declining in the United States. In other words, an evolutionary psychological perspective on social capital can explain why we are now bowling alone.
Our theoretical aim is therefore twofold. We first aim to argue that any non-arbitrary and non-ad hoc definition of capital (social or otherwise) requires a general theory of values. We then attempt to demonstrate, by our discussion of four empirical puzzles, that evolutionary psychology is currently the best contender for such theory of values. It is important for us to point out at the outset that, by values, we mean internal states that motivate behavior (Hechter, 1992, 1994). Values are therefore roughly synonymous with preferences or desires (albeit more general than the latter), and there is absolutely no suggestion that human values are moral, desirable, or good by some societal standards. For a Harvard MBA student, academic excellence and lucrative jobs are values. For a drug lord, selling illegal drugs to as many people as possible by any illicit means available is a value. Both individuals do what they do because of their values; their values motivate their behavior.
Social Capital from an Evolutionary Psychological Perspective
Because evolutionary psychology has made significant advances in the social sciences in the last couple of decades, we will not present a general introduction to the field here. Interested readers may consult Barkow et al. (1992), Buss (1995, 2004), Cartwright (2003), Daly and Wilson (1988), and Kanazawa (2001a). Popular introductions to the field include Buss (2003), Miller and Kanazawa (2007), Ridley (1993), and Wright (1994).
From an evolutionary psychological perspective, reproductive success, making as many copies of one’s genes as possible, is the ultimate (albeit largely unconscious) goal of humans (as it is for all other species), or, more precisely, the goal of their genes, and all other goals are secondary and subsequent to it (Dawkins, 1989; Kanazawa, 2004). Even survival is a means to reproductive success. From this perspective, we are all put on this earth to reproduce; we are created and designed to reproduce by evolution by natural and sexual selection. That’s the reason why humans exist; that’s the reason why amebas exist. The fact that many of us don’t think that’s the ultimate reason for human existence or that some of us choose not to reproduce is irrelevant. We are no more privy to the evolutionary logic behind our design than amebas are, and, no matter what we choose to do in our own lifetimes, we are all descended from people who chose to reproduce. None of us inherited our psychological mechanisms from our ancestors who remained childless.
Whether we like it or not, whether we know it or not, reproductive success is the ultimate goal of all living organisms, including humans, and everything else is a means toward it. For humans, a K-strategy species, 1 this means that they reproduce a small number of children and invest heavily in them so that they will reach the age of sexual maturity and reproduce themselves. Having children in itself does not necessarily accomplish reproductive success. If many or most of them die before they can reproduce themselves, then the parents have managed to leave very few copies of their genes. Parents instead must make sure that their children themselves will have children.
1 K-strategy species, such as humans and other great apes, reproduce a few offspring, and care for and invest in them heavily to ensure that most or all of them will grow to sexual maturity. In contrast, r-strategy species, such as most fish species, reproduce millions of offspring at a time but do not care for or invest in them at all (MacArthur & Wilson, 1967).
Social capital from an evolutionary psychological perspective is therefore any resource that inheres in relationships between individuals that, directly or indirectly, helps them attain reproductive success in a given situation. Various aspects of social relationships (such as trust and associations with others) (Paxton, 1999, pp. 97-104) qualify and count as social capital only to the extent that they help individuals do so. Social relationships that do not even indirectly or remotely contribute toward individuals’ reproductive success do not count as social capital.
An evolutionary psychological perspective on social capital suggests a hierarchy of values (Kanazawa, 2001a). It specifies reproductive success as the ultimate goal, but is otherwise compatible with a variety of proximate goals which help the actors attain reproductive success in their specific circumstances. For example, an evolutionary psychological perspective on social capital is compatible with a theory of why men in some societies compete to acquire greater hunting skills or an entirely different theory of why men in other societies aim to attain quality university and postgraduate education. Human behavior in any given circumstances is a function of both their ultimate and proximate goals. Sometimes the pursuit of proximate goals interfere or even circumvent the pursuit of the ultimate goals, as when people postpone or forego having children in order to pursue higher education. While evolutionary psychology is one contender for the theory of values, it is by no means the only one, and it cannot by itself explain all of human behavior in all circumstances.
A very important implication of an evolutionary psychological perspective on social capital is that what counts as social capital is often different for men and women. In the ancestral environment, where our ancestors were hunter-gatherers, there was a clear division of labor between the sexes. It was the male who attained greater status through game hunting and competition, while the female took physical care of the children. Ancestral women gathered plant foods and thereby contributed to the nutritional needs of their children, but their childcare responsibilities prevented them from devoting themselves to attaining greater status, as men did. Ancestral men with higher status were better able to protect and provide for their children than those with lower status, and their children had greater chances of survival to sexual maturity. For example, Hill and Hurtado (1996, pp. 316-371, p. 328, Table 10.6) note that, among the Ache Indians of Paraguay, men’s status strongly correlates with their hunting skills, and their status has a significantly (p < .0001) positive effect on their fertility; more skilled hunters with higher status father more children in this hunter-gatherer society. There is evidence to suggest that, for this reason, women to this day are attracted to men with higher status and greater resources in all societies (Buss, 1989; Kanazawa, 2003).
Evolved psychological mechanisms or psychological adaptations, such as the one that produces criteria by which women judge their potential mates, are adapted to the conditions of the ancestral environment, not necessarily to the current environment. The fact that women themselves can attain higher status through their own effort today is irrelevant; it has not altered their psychological mechanisms and the desires and preferences they engender, just as the fact that food is abundant today has not altered our preference for sweet and fatty food, which contain higher calories necessary for survival in the ancestral environment. Throughout evolutionary history, higher status was men’s means to reproductive success, whereas physically taking care of the children was women’s. Thus any social relationship that helps men attain higher status counts as social capital for men, but not for women. In contrast, any social relationship that helps women take better care of their children counts as social capital for women, but not for men.
We have elsewhere proposed that there are sex differences in human sociality (Savage & Kanazawa, 2004) and that men and women experience differential pleasure and anxiety in certain social relations due to the benefits these responses would have had in the ancestral environment. For instance, we would expect women to experience greater anxiety leaving a baby behind, or at the sound of its cry, than men would. In the current environment, however, it is sometimes in the best interest of the children for the mothers to leave the home for gainful employment. In the ancestral environment, it would have enhanced reproductive success for women to feel profound anxiety when leaving their children behind; the same anxiety when dropping off a child at the day care center works against the women’s reproductive success today. Although humans are adaptive to some extent and can make changes in their behavior, they may find that their values and preferences for certain social relationships (and the associated anxieties and pleasures) have remained the same (Kanazawa, 2001a). From an evolutionary psychological perspective, some of the anxiety problems and neuroses that humans experience today may result from the inconsistency between the innate feelings and situational exigencies.
An evolutionary psychological perspective on social capital is entirely consistent with the growing body of literature on the sex differences in the antecedents and consequences of social capital. The feminist perspective on social capital culminates, among others, in the recent publication of the volume Gender and Social Capital (O’Neill & Gidengil, 2005). Scholars have suggested, for example, that social capital affects the outcomes of migration differently for men and women, in such widely varied societies as Thailand (Curran, Garip, & Tangchonlatip, 2005) and Puerto Rico (Aguilera, 2005). While evolutionary psychology concurs with the feminist perspective in highlighting the sex differences in the causes and effects of social capital, the two perspectives offer different explanations for the underlying mechanisms.
Empirical Puzzles Why Do Women Have More Kin in their Personal Networks than Men Do?
Empirical studies on personal networks repeatedly demonstrate that otherwise comparable men and women have similar personal networks. The only exception to this rule is that women have more kin and fewer coworkers in their personal networks than men do (Campbell, 1988; Fischer & Oliker, 1983; Marsden, 1987). While there appears little doubt that this sex difference in personal networks exists, few in network theory seems to know why. Why do women have more kin in their personal networks than men do?
An evolutionary psychological perspective on social capital can answer this question, as a function of sex differences in the need for kin in order to achieve reproductive success. The fact that the female gamete (egg) is greater in size and fewer in number than the male gamete (sperm) (which is the biological definition of male and female), and the fact that gestation takes place within the female body, together lead, directly or indirectly, to almost all of the sex differences in preferences and behavior. One of these differences is parental investment. Across all species for which these two conditions hold, the female makes greater parental investment than the male (Trivers, 1972). In fact, for most species, the male parental investment is limited to the sperm deposited inside the female body during copulation. The sex difference in parental investment occurs because males under these conditions have far greater fitness ceiling than the females do; males can produce a far larger number of offspring in their lifetime than females can.
This is true of humans as well. Thus, while reproductive success is equally important to men and women, each child is far more valuable to a woman than to a man because it represents a greater share of a woman’s lifetime reproductive potential than a man’s. Men are exceptional in nature in that they make a large amount of parental investment in their offspring (compared to males of other species). Nonetheless, women (just like females of most other species) still make far greater parental investment in their children than men do, because women’s evolved psychological mechanisms compel them to do so.
Another consequence of the internal gestation of the fertilized egg inside the female body, not the male body, is the twin concept of maternity certainty and paternity uncertainty. Mothers are always certain of their maternity, whereas fathers can never be absolutely certain of their genetic relatedness to the children of their mates. By the same token, individuals are certain to be genetically related to their maternal kin (mother, maternal grandmother, aunts and uncles on the mother’s side), whereas they can never be certain of their genetic relatedness to their paternal kin.
Women are therefore more motivated to make parental investment than men are. However, women cannot always do it alone; sometimes, they need help from others, especially in the ancestral environment where resources were scarce and life was precarious. When mothers need help in their effort to raise their children, nobody is more likely or willing to deliver it than their kin. Women’s kin are sometimes even more motivated to invest in the children, materially or otherwise, than the putative fathers are, due to paternity uncertainty. 2 For the same reason, paternal kin are not as motivated to invest in the children as maternal kin are. We suggest that this is why women, even today, have a larger number of kin in their personal networks than men do.
2 More precisely, whether the putative father or the maternal kin are more motivated to invest in the children crucially hinges on the level of paternity uncertainty (the probability of cuckoldry). The biological father shares 50% of his genes with the child (coefficient of relatedness r = .50) whereas maternal grandparents and maternal uncles and aunts share 25% of their genes with it (r = .25). It means that, as long as paternity uncertainty is less than .50 (the probability of cuckoldry p < .50), then the biological father is still more closely related to the child on average than the maternal kin. It is only when p > .50 that maternal kin are more closely related to the child and thus more motivated to invest in it than the putative father. In some tribal societies where paternity uncertainty is consistently high, it is the maternal uncle, not the putative father, who is expected to invest in the child.
Consistent with this explanation, Kanazawa (2001b) reports that family income has a significantly (p < .01) negative effect on the kin density (the proportion of personal network ties that are kin) among women, while it has no effect on men’s kin density. This may be because women with more resources need less help from their kin in raising their children than women with fewer resources. Similarly, being currently married has a significantly (p < .01) negative effect on women’s kin density, but not on men’s. This may be because married women can rely on their husbands in raising their children, while currently unmarried women don’t have this option and sometimes have to resort to their kin in order to get help.
From our perspective, women have more kin in their personal networks because such networks count as social capital. Women’s close ties with their kin help them better raise their children. Women’s kin are (unconsciously) motivated to help invest in the children because they are certain to be genetically related to them. In contrast, close ties with kin do not count as social capital for men because they do not help them attain reproductive success. Men’s kin are (unconsciously) less motivated to invest in the children because they cannot be certain that they are genetically related to them, and such ties do not usually help men attain greater material resources and higher status (their principal means to reproductive success). Further, our perspective on social capital can simultaneously explain why men are more likely to have coworkers in their personal networks because their ties to coworkers often do help them attain greater resources and status in the workplace. Men have evolved preferences for all-male relationships which would have constituted valuable social capital in the ancestral environment because of the need for male-male coalitions in cooperative hunting, politics, and warfare (Tiger, 1969).
Why Are Black Women More Likely to Have Children Out of Wedlock?
In the United States, black women are far less likely to marry and far more likely to have children out of wedlock. In 1998, 21.9% of all white women, 15 and older, had never been married. The corresponding figure for black women was nearly double (41.5%) (Lugaila, 1998). In the same year, 22% of all births to white women were out of wedlock. The corresponding figure for black women is more than triple (67%) (Bachu & O’Connell, 2000). In other words, the incidence of out-of-wedlock births among black women is so high that only one third of black children are born to married couples. What explains this racial disparity and such a high incidence of out-of-wedlock births among black women?
Recall that, from an evolutionary psychological perspective, no social relationships are inherently good or bad. No ties or associations automatically increase social capital. Social relationships and ties increase social capital only to the extent that they help individuals attain reproductive success. Even such fundamental and seemingly biological ties as marital relationships are not exempt from this rule. Marital relationships increase social capital only to the extent that they help individuals attain reproductive success. As Wilson (1987) points out, however, young black men, for a variety of reasons, do not often make good providers. They are far more likely to be in jail or unemployed than their white counterparts; a relatively few young black men are “marriageable” (Wilson, 1987). Many young black men are therefore not in a position to make parental investment in their children. Young black women do not increase their reproductive success by marrying them, especially since many of them collect public assistance, which they’d have to forfeit if they get married.
The gross racial disparity in the rates of marriage and out-of-wedlock births is perfectly consistent with an evolutionary psychological perspective on social capital. The perspective also reminds us that, just as what counts as social capital is often different for men and women, it may also be different for blacks and whites (and possibly between other groups in society). Marital relationships do not count as social capital for black women nearly as much as they do for white women, and the fact that black women often are not in marital relationships does not by itself mean that they have less social capital than white women. Unmarried black women with children often cultivate ties to kin to get help and material resources to invest in their children. Their lack of marital relationships does not signify a lack of social capital if such marital relationships do not help them raise their children, and if they have other ties that accomplish this goal.
Why does Social Capital Appear to Have Opposite Effects on Men and Women?
Burt (1998) notes that “women pose a puzzle” in his detailed study of social capital within a large American electronics firm. His structural hole theory (Burt, 1992) predicts that those who occupy structural holes (network nodes connected to other nodes that are themselves not connected) have social capital because they can function as information brokers. They have access to a unique set of information and network ties that few others have (Burt, 2004). Burt’s theory predicts that those who occupy such structural holes will attain higher status within the firm as a result.
His data (Burt 1998, Figure 2) confirm his hypothesis, but only among male managers. Male managers who occupy many structural holes are promoted significantly (p < .001) earlier than expected, and those who occupy few structural holes are promoted significantly slower than expected. The puzzle is that the pattern is the exact opposite among female managers: Those who occupy many structural holes are promoted significantly (p < .01) slower than expected, while those who occupy few structural holes are promoted significantly earlier than expected. What accounts for this puzzle?
Burt’s fascinating results once again remind us of the need to conceptualize and measure social capital differently for men and women. As we have stressed above, higher status (which promotion within a firm brings) has been men’s means to reproductive success throughout the evolutionary history. Men of higher status and greater resources have always attracted more mates and been able to provide for their offspring to assure their survival to sexual maturity. Higher status has never been women’s means to reproductive success (Kanazawa, 2003).
An evolutionary psychological perspective on social capital can therefore account for Burt’s otherwise inexplicable puzzle. It explains why men who occupy structural holes use the social capital to win earlier promotions; structural holes indeed count as social capital for men because they help them achieve higher status, which they can then use to attain reproductive success. An evolutionary psychological perspective can simultaneously explain why the same pattern does not hold for women. It does not necessarily mean that social capital has different effects for men and women; it means that structural holes may not count as social capital for women. To the extent that women in structural holes do indeed possess unique information and personal ties, we would expect them to use such advantage directly to take care of and invest in their children, not to win early promotions. In this sense, female managers in possession of valuable information have better use (reproductively speaking) to which to put it; they have better things to do than to “waste” such valuable information on earning promotions. Once again, in order to know whether structural holes count as social capital for men and women alike, we need to know what men and women want. In order to know what they want, we need a theory of values.
Why Are We Bowling Alone Now?
In a now classic article, Putnam (1995) argues that social capital in the United States has been declining over the last two decades. His evidence comes from the General Social Survey’s (GSS) data on organizational memberships. The GSS routinely asks its respondents whether they belong to any of a large number of groups. The complete list of groups that the GSS uses to measure “socio-political participation” includes: Fraternal groups, service clubs, veterans’ groups, political clubs, labor unions, sports groups, youth groups, school service groups, hobby or garden clubs, school fraternities or sororities, nationality groups, farm organizations, literary, art, discussion or study groups, professional or academic societies, church-affiliated groups, and any other groups. Putnam demonstrates that Americans’ participation in these groups has been declining in the past two decades, and their “civic engagement” and social capital are thus eroding.
An evolutionary psychological perspective on social capital suggests that this conclusion may possibly be premature. Just as there is nothing sacred about marital relationships (they count as social capital only to the extent that they facilitate reproductive success), there is nothing inherently good about participation in any of the groups that the GSS lists. Memberships in such groups count as social capital only to the extent that they help individuals achieve reproductive success. The decline in memberships in the same set of groups demonstrates decline in social capital only if the groups serve the same functions to individuals and their reproductive success over the entire period. If the groups’ functions for individuals have changed, then a decline in their memberships does not necessarily indicate a decline in social capital. It is instructive to note that the GSS has asked about the same set of groups listed above since its inception in 1972 while the American society has changed a great deal. It has made the transition from a predominantly industrial society to a predominantly postindustrial society. Local and regional economies and labor markets have given way to national and international ones. Gone are the days when many Americans (or even several generations of them) spent their entire lives in their home town, going to school, getting a job, finding a spouse, raising a family, and retiring without ever setting a foot outside of their county or state.
In the local and regional economies and labor markets of yesteryear, individuals’ ties to friends and neighbors nearby were very important in their pursuit of reproductive success. Men often got their jobs through such informal ties (Granovetter, 1974), and women exchanged valuable information about schools, churches, doctors, and dentists with other women in their neighborhood. People needed to rely on each other for emergencies, like when they or their children fell ill. For both men and women, participation in local groups was thus important in getting jobs (accumulating resources and attaining status) and raising a family, in other words, in their pursuit of reproductive success.
In the global economy of today, men and women are more likely to find their jobs in the Wall Street Journal or the Financial Times (and their online versions). They have cell phones and the nationwide 911 emergency call system to get help in times of need. They have grocery stores and drug stores open 24 hours a day. Vital information about schools, churches, doctors and dentists is now available through the internet. In other words, participation in local groups no longer facilitates their attempt to get jobs and raise their families, to attain reproductive success. Had the GSS included in its surveys other types of groups that did not necessarily exist in 1972 but are now essential for people’s lives (for instance, membership in an HMO, Sam’s Club or subscription for broadband internet connection), we would predict that their participation in these new groups is still high.
It is instructive to note in this regard that, while participation in almost all the groups in the GSS surveys has declined or at most held steady over the last quarter century, membership in professional and academic societies, the only distinctly national and international groups on the GSS list, has increased from 13.2% in 1974 to 18.7% in 1994 (http://csa.berkeley.edu). No other groups have undergone a similar increase in membership, with the possible exception of sports groups (“gym”). Paxton’s (1999, p. 116, Figure 10) multiple indicator model demonstrates that, while the GSS respondents’ association with specific individuals and groups may have declined over the years, their latent tendency toward association in general has not declined at all.
An evolutionary psychological perspective on social capital would not predict a sharp decline in social capital at any time, because to forsake social capital is to forgo the ultimate goal of all human behavior: reproductive success. It would instead predict that the ultimate level of social capital, defined as any resource inherent in relationships between people that help them attain reproductive success, will remain more or less the same, even though the types and nature of relationships people have might change as the society changes. Humans have for millions of years cultivated and maintained relationships that help them attain reproductive success; we would not be here today if they didn’t. We would not expect human nature to change now. We are bowling alone now because participation in local bowling leagues (or any other local groups) no longer help us attain reproductive success as much as they used to, but that does not mean that we have less social capital.
We understand the appeal of focusing on the construct of social capital in order to understand social life. But because social capital inheres in relationships it is important to understand individual motivations for establishing and maintaining relationships in the first place. We therefore believe that an overemphasis on narrow empirical questions like “Does social capital reduce the odds of school drop out?” (Croninger & Lee, 2001; Teachman, Paasch, & Carver, 1996) is largely misguided. The recent lament that social capital is in decline (Putnam, 1995) demonstrates a very narrow view of social life and very short memory of human history. Americans today are upset to see that there are fewer and fewer nuclear families and that social institutions that we fondly recall from our youth (the welcome wagons, Boy Scouts, and bowling leagues) are on the wane. If we take a longer view of history, however, we soon realize that such institutions were only common for a relatively short period in our history. In earlier years, families were often torn apart — mothers died in child birth, children died from accidents and diseases, wars killed many young men. Boy Scouts and bowling leagues had not been invented. Throughout human evolutionary history, the nuclear family has been the exception, not the norm (Salmon & Shackelford, 2007). The nature of social ties varies a great deal across space and time, and the reliance on any narrowly focused measures of “social capital” or positive life outcomes (such as school attendance) is likely to result in inconsistent empirical findings.
In this paper we advance an evolutionary psychological perspective on social capital. We reiterate and emphasize our point that evolutionary psychology is but one perspective on social capital. It has the advantage of offering a clear definition of what social capital is from metatheoretical first principles, which few other perspectives can. However, we encourage others to propose their own theories and clear definitions of social capital, and subject competing hypotheses (including ours) to rigorous empirical tests. Such alternative theories of social capital must clearly specify the ultimate values for human actors (other than reproductive success).
Apart from its ability to solve some empirical puzzles, we believe an evolutionary psychological perspective on social capital has several distinct advantages: what, why, when, where, and how. First, an evolutionary psychological definition of social capital can finally tell us what exactly social capital is. While there has been a great deal of discussion of the concept, there currently is no clear consensus as to what social capital is (Lin, 2000; Portes, 2000). This is because one needs a theory of values in order to define capital (social or otherwise), and there presently is no widely accepted theory of values that explains what humans want.
Second, an evolutionary psychological perspective, which is one of the current contenders for a general theory of values (Horne, 2004), can tell us why social capital is important, and, in a more general sense, why humans are social (Savage & Kanazawa, 2004). While everyone recognizes that humans are social, they may not necessarily know why. From an evolutionary psychological perspective, humans (and members of many other species) are social because their sociality promotes reproductive success. Human sociality is largely how our ancestors survived long enough to reproduce and raise their offspring. That is why humans are social and that is why social capital is important for humans.
Third, an evolutionary psychological perspective can tell us when and where we expect humans to maintain their social ties. While the perspective explains why humans are social, it does not predict them to be universally and indiscriminately social. Human are social and maintain their social ties with others only when and where such ties help them attain reproductive success (Kanazawa, 2001b). They join bowling leagues and other local groups, if doing so ultimately promotes their reproductive success, but not if otherwise.
Finally, an evolutionary psychological perspective on social capital, with its clear definition of the concept, can tell us precisely how to measure it at different times and in different societies. It would strongly argue against using the same measure across time and places, because which relationships promote reproductive success can vary across time and places. An evolutionary psychological perspective compels us to count as social capital only those relationships that, directly or indirectly, promote individuals’ reproductive success.