What explains the age profiles of geniuses and criminals?

In a previous post, I explain that, regardless of what they do, whether they be geniuses or criminals, men’s productivity has an identical age profile. It quickly peaks in late adolescence and early adulthood, and then equally quickly declines throughout adulthood. What explains this common age profile?

It turns out that a single evolutionary psychological theory may be able to explain the productivity of both creative geniuses and criminals over the life course. According to this theory, both crime and genius are expressions of young men’s competitive desires, whose ultimate function in the ancestral environment would have been to increase reproductive success.

As I explain in an earlier post, there are reproductive benefits of intense competitiveness to men. In the physical competition for mates, those who are competitive may act violently toward their male rivals. Their violence serves the dual function of protecting their status and honor, and discouraging or altogether eliminating their rivals from future competition. Their competitiveness also inclines them to accumulate resources to attract mates by stealing from others, and the same psychological mechanism can probably induce men who cannot gain legitimate access to women to do so illegitimately through forcible rape. Men who are less inclined toward crime and violence may express their competitiveness through their creative activities in order to attract mates.

There are no reproductive benefits from competition before puberty because prepubescent males are not able to translate their competitive edge into reproductive success. With puberty, however, the benefits of competition rapidly increase. Once the men are reproductively capable, every act of competition (be it through violence, theft, or creative genius) can potentially augment their reproductive success. The benefits of competition stay high after puberty for the remainder of their lives because human males are reproductively capable for most of their adult lives.

This is not the whole story, however. There are also costs associated with competition. Acts of violence can easily result in the man’s own death or injury, and acts of resource appropriation can trigger retaliation from the rightful owners of the resources. A man’s reproductive success is obviously compromised if the competitive acts result in his death or even injury. Before men start reproducing (before their first child), there are few costs of competition. True, being competitive might result in their death or injury, and they might therefore lose in the reproductive game if they are too competitive. However, they also lose by not competing. As I explain in a previous post, if they do not compete for mates in a polygynous society, which all human societies are, they will be left out of the game and end up losing as a result In other words, young men might lose if they are competitive, but given polygyny, they will definitely lose if they are not. So there is little cost of being competitive, even at the risk of death and injury; the alternative -- being a total reproductive loser -- is worse in reproductive terms, which once again is the reason the death penalty cannot deter young men.

The cost of competition, however, rises dramatically with the birth of the first child and subsequent children. True, men still benefit from competition because such acts of competition might attract additional mates even after their initial reproduction. However, a man’s energies and resources are put to better use by protecting and investing in his existing children. In other words, with the birth of children, men should shift their reproductive effort away from mating and toward parenting. If the men die or get injured in their acts of competition, their existing children will suffer; they might starve without their father’s parental investment or fall victim to predation by others without their father’s protection. The costs of competition therefore rapidly increase after the birth of the first child, which usually happens several years after puberty because men need some time to accumulate enough resources and attain sufficient status to attract their first mate. Nevertheless, in the absence of artificial contraception, reproduction probably began at a much earlier age in the ancestral environment than it does today. There is therefore a gap of several years between the rapid rise in the benefits of competition and the similarly rapid rise in its costs.

Both the age-crime curve and the age-genius curve can be explained as the mathematical difference between the benefits and costs of competition. Young men rapidly become more violent, more criminal, and creatively more expressive in late adolescence and early adulthood as the benefits of competition rise, but then their productivity just as rapidly declines in late adulthood as the costs of competition rise and cancel its benefits. Criminality, genius, and productivity in virtually everything else men do vary as they do over the life course because they represent the difference between the benefits and costs of competition.

These calculations have been performed by natural and sexual selection, so to speak, which then equips male brains with a psychological mechanism to incline them to be increasingly competitive immediately after puberty and to make them less competitive right after the birth of the first child. Men themselves do not necessarily make these calculations consciously. They simply do not feel like acting violently, stealing, or conducting additional scientific experiments, or they just want to settle down after the birth of the child, but they do not know why. The intriguing suggestion here is that a single psychological mechanism may be responsible for much of what men do, whether they are criminals or scientists.

Now, given that human society has always been mildly polygynous, there were always many men who did not succeed at securing mates and reproducing. These men had everything to gain and nothing to lose by remaining competitive and violent for their entire lives. However, we are not descended from these men.

By definition, we are all descended from men (and women) who attained some reproductive success. None of us are descended from total reproductive losers who left no offspring. And we are disproportionately descended from those who attained great reproductive success. Twelve children carry the genes of a man who had twelve children, but only one child carries the genes of a man who had only one child. And, of course, no children carry the genes of a man who had no children. (Yes, childlessness is perfectly heritable!) Contemporary men did not inherit from reproductive losers psychological mechanisms that force them to stay competitive and keep trying to secure mates for their entire lives. We all act as if we have children by the time we reach early adulthood, whether we do or not, because we are descended, and inherited our psychological mechanisms, from our ancestors who did.