As a rather social species, humans seem to have a fairly advanced theory of mind. By that, I mean we attribute things like beliefs, intentions, desires, and so on to other people in efforts to understand, explain, predict, and manipulate the behavior of others. The adaptive value of this skill can be hard to overstate and, accordingly, we ought to expect people to be pretty accurate at figuring out the mental states of others. That said, doing so with perfect accuracy is not an easy task, despite our general proficiency with it. Part of the reason, of course, is that things like beliefs and desires are not themselves directly observable, requiring us to make certain assumptions about the reasons for the observable behavior of others. Another part of the reason, however, is that people often have a vested interest in convincing others about certain internal states of affairs, and that interest persists even in the absence of truth value. For instance, if my suffering tends to draw investment from others in the form of social or material resources, it might pay for some cognitive mechanism of mine to over-represent how much I am suffering publicly to others.

“No, really; I am in that much pain. Just come a little closer and see…”

As an example of the trickier aspects of figuring out the intentions and motivations of others, I wanted to use a case of paternal investment in humans. In many mammalian species, males do not tend to assist in the raising of offspring at all. This is owing largely to the fact that males cannot be assured of their paternity the way females can “know” the child they give birth to is theirs. Human males, by stark contrast, often offer substantial investment in children. However it came about, males in our species managed to largely solve the adaptive problem of paternity uncertainty. The key word in that last sentence, though, is largely: we still can’t be sure that a child is ours 100%, so we might expect that, in general, men are less interested in investing in children than women tend to be, especially if the specter to infidelity has been raised. We might also expect that outcome to obtain owing to opportunity costs; what else we could be doing with the time spent investing in children. Time and energy that I spend investing in raising a child is often time and energy I can’t spend doing other adaptive things, like pursuing additional mating opportunities. As the obligate costs to reproduction are lower for men than women, we might also expect men are more interested in putting their time into pursuing mating opportunities and less interested in putting into investment in children, relative to women.

Now these are theoretically-sound evolutionary reasons for expecting the sex with less obligate investment and genetic certainty (typically males) to be less interested in parenting efforts. The logic of managing these adaptive problems should be instantiated in the psychologies of men and women, and to the extent that men and women face different problems, we should perceive the world and behave in different ways. However, some people don’t like the idea that there is any difference between men and women with respect to how interested they are in raising children. As an example, I would offer this article over at Patheos calling Sam Harris a sexist for suggesting men and women have some different interests when it comes to raising children. In it, the author puts forth two hypotheses: that women being the ones to disproportionately cut their careers short to raise children is due to either “…biology or sexism“. In this case, the author favors the “sexism” explanation which, I think, is that men and women and psychologically indistinguishable with respect to their interest in raising children, and would be just as likely to do so were it not for whatever culture is setting different standards. The author’s theory of mind, then, says that men are just as interested in raising children as women (or at least that’s what one part of her mind says publicly). The notable quote I would consider to outline this hypothesis is, “There is no biological reason men and women cannot share the responsibility of childrearing“. No biological reason making such an outcome impossible, sure; just that a host of them make an equitable distribution of interest in doing so fairly unlikely.

The piece and subsequent comments sections are full of anecdotes about how people know men who are supremely nurturing towards children. I don’t doubt that’s the case, just like I don’t doubt that there are some women who are taller than most men. Variance is a thing, after all, and males in our species do tend to invest in children. It doesn’t follow, though, that there are no aggregate differences in desire rear children between the sexes owing to more than sexist culture. The important thing worth noting here is that desires to invest in children are being inferred from the behavior of investing. The problem with doing so is that people might enact behavior for reasons other than desiring to enact the behavior itself. An easy example is a man visiting a prostitute: just because the man gives the prostitute money, it does not mean his motives are altruistic; he is giving her money instrumentally. If he didn’t have to give her money for the sex, he probably wouldn’t. That sounds simple, I’m sure, but how about the hypothesis that men invest in child rearing for reasons owing to mating effort, rather than parenting effort?

“HA; Got one! Bring on the ladies!”

This brings me to a paper by Anderson, Kaplan, & Lancaster (1999). Now this study doesn’t speak to the matter of sex differences in interest in children, as it only focuses on male behavior, but it makes the point well that inferring motives from behavior can be a problem. The study examined male investment in children in conjunction with their relationship status with the child’s mother. There were four groups the men were placed into: (1) those who had genetic children and were in a relationship with the mother, (2) those who had genetic children and were not in a relationship with the mother, (3) those who had stepchildren with a woman they were in a relationship with, and (4) those who had stepchildren from a past relationship. The researchers had a sample of approximately 1,300 men with offspring in one or more of those categories. The question at hand was whether or not a male’s investment in said children varied as a function of the male’s relationship status with the child’s mother and the children themselves. The male’s investment was considered in four groups: (1) Time spent with the child, (2) money spent on the child, (3) whether the child attended college, and (4) how much support the child received for college.

I want to focus on the monetary investment category, as I feel it’s the easiest to think about, (and because all four classes of investment showed basically the same pattern). With respect to monetary investments over the past year to children 17 or younger, genetic children from a previous relationship received, on average, about $700 less than similarly-aged genetic children from the current relationship (less, in this case, refers to how much a statistical model accounting for a number of factors predicted the typical child should get). By contrast, stepchildren from the current relationship received only around $150 less than genetic children from a current relationship.Stepchildren from a previous relationship received about $1,500 less than genetic children from the current relationship, and $900 less than genetic children from previous relationships. For children age 18-24, the same pattern held, with the exception of the genetic children from past marriages receiving more money than stepchildren from the current one, though the two categories did not differ significantly.

These results found that men do indeed tend to invest in children; often substantial amounts. This fact was never in question. However, the amount they invested in the child, whether in terms of time or money, varied contingent on their genetic relatedness to the child and relationship with the child’s mother. Some of men’s interest in investing in children, like women’s, owes to their relatedness to the child: genetic children from past relationships received much more investment than stepchildren from past relationship. This is classic kin selection. I presume very few people would suggest that parents tend to invest in their own children more because “their culture tells them to do so”, rather than positing some kind of biologically-grounded reason. It also seems like a hefty portion of the investment in children by men could reflect mating effort towards the mother: the men behaved as if they were trying to build or maintain a relationship with a woman through investing in her children. Sure; it might not be as romantic as a dinner date, but investment is investment. It follows that men might well be less interested in raising children per se, but quite interested in maintaining a relationship with the mother, so they invest at certain levels despite their lack of intrinsic interest. Put another way, it is quite plausible that women with children do not generally wish to be in relationships with partners that abuse or neglect the child, so men try to avoid that in order to not be ruled out as mates.

“Ladies…”

Now, again, I don’t have comparable data for women, but the point at hand is that just because you find men investing in children, it doesn’t mean that their sole motivation is in the investing per se. We could very well find that men and women invested relatively equally (or unequally) in children and that their motives for doing so differ substantially. It is also possible that the people agreeing with the sentiments expressed in the Patheos article represent something of a biased sample, insomuch as they don’t know many men who dislike taking care of children because they wouldn’t want to (and purposefully don’t) associate with such men in the first place. At the very least, I doubt any of them are giving fathers who ran out on their children pats on the back and telling them they understand. Finally, it is also possible that people might be inferring certain motivations on the part of one sex or the other in hopes of convincing people of some particular political viewpoint or to affect a change in their behavior. Though I don’t have much time to speculate about it, if people have a vested interest in seeing sexism as being responsible for a difference between men and women, you can bet they will find it. Similarly, psychological researchers often have a vested interest in finding certain statistical results and, lo and behold, they tend to find them too. If you’d like to speculate more about men and women’s interest in raising children, sexist biases, and the like, I’ll leave you with some helpful places to do just that.

References: Anderson, K., Kaplan, H., & Lancaster, J. (1999). Paternal care by genetic fathers and stepfathers I: Reports from Albuquerque men. Evolution & Human Behavior, 20, 405-431.