What do evolutionary psychologists have to say about killing one's wife? Here is a bit from a post by Satoshi Kanazawa from his Psychology Today blog:
When Martin Daly and the late Margo Wilson first began studying domestic violence and uxoricide (the killing of one’s wife) in the early 1980s, they had competing explanations. Daly hypothesized that domestic violence and uxoricide resulted when the husband did not value his wife sufficiently and mistreated her as a result. Since a wife’s fertility and reproductive value decline with age, Daly predicted that older, less valuable wives were at a greater risk of spousal abuse and homicide than younger, more valuable wives.When evolutionary psychology was first put forward it was treated as non-science, as "just so" stories. But the above shows you that the theories of evolutionary psychology can be tested. It is science.
Wilson, in contrast, hypothesized that domestic violence and uxoricide were a maladaptive byproduct of the husband’s inclination and tendency to guard his wife to make sure that she did not have sexual contact with other men. Because men should be more motivated to guard younger, more valuable wives, Wilson predicted that younger wives were at a greater risk of spousal abuse and homicide than older wives.
Both explanations use impeccable evolutionary psychological logic and derive from known first principles, but both predictions could not be true simultaneously. So Daly and Wilson got to work, as the great scientists that they were, and collected data on domestic violence and uxoricide in Canada and the United States. And they put their two competing hypotheses to an empirical test. Their data showed that younger wives were at a much greater risk of domestic violence and murder than older wives. In the end, Wilson’s prediction turned out to be true, and Daly’s false. Are evolutionary psychological explanations untestable and unfalsifiable?
Astute readers may be thinking right now, “But younger women are usually married to younger men. And younger men are more violent than older men, as you point out in your discussion of the age-crime curve. So younger women are at a greater risk of spousal abuse and murder, not because they are young but because their husbands are young and therefore more violent.”
Close, but no cigar. While it is difficult to separate the effects of the husband’s age and the wife’s age, because the two are indeed highly correlated, careful statistical analyses show that the wife’s age almost entirely determines the likelihood of being a victim of spousal abuse and homicide. Middle-aged husbands (ages 45-54) legally married in Canada to much younger wives (ages 15-24) are more than six times as likely to kill their wives than young husbands (ages 15-24) married to women of similar age. Among common-law marriages, middle-aged husbands married to much younger wives are more than 45 times as likely to kill their wives as young husbands. The effect of the wife’s age is so powerful that it overrides and even reverses a man’s tendency to become less violent with age. Thus, while it is true that younger men in general are much more violent and commit more murders than older men, young and old men kill different types of people. Young men kill other men (their male sexual rivals); older men kill their wives. As a result, the proportion of men among murder victims declines as the murderer’s age increases. For murderers aged 15-19, 86.3% of the victims are males; for murders aged 65-69, only 51.4% of them are males.
Here is another example of Satoshi Kanazawa applying evolutionary psychology to a puzzle. I like this example because it shows -- yet again -- that rational choice theory is wrong-headed and a profound mistake, a mistaken theory which has captivated economists far too long:
The fact that the death penalty does not deter murder is a puzzle for the social scientists, especially rational-choice microeconomists. From a microeconomic perspective, each actor makes a deliberate and careful cost-benefit analysis before making any decision. The lack of deterrence effect of the death penalty is therefore puzzling from this perspective, unless the probability of detection, arrest, prosecution, and conviction is infinitesimal. No matter what the actors want, they cannot pursue and consume it if they are dead. So, from the microeconomic perspective, there should be very few occasions where it makes sense for rational actors to decide to commit murder at a realistic risk of execution.Economics is a useful science, but not in the hands of the rational choice school and neoclassical economics, you get a theory that ignores real human behaviour. Hopefully the newer sciences of neuroeconomics, behavioural economics and other heterodox schools of economics will get some traction. The Great Recession should put the QED to the inadequacy and falsity of rational choice and neoclassical economics.
From an evolutionary psychological perspective, however, the lack of deterrence effect of the death penalty is not a puzzle at all. First, contrary to microeconomics, murder in most cases is not a deliberately planned action. It usually begins with “trivial altercations,” where one man insults another by questioning his honor, status, and reputation. They begin a fight, which escalates to the point where one man ends up dead. The death penalty does not deter murder because there is very little forethought and cost-benefit analysis involved in it. Men usually do not consciously decide to commit murder. The death penalty may deter other types of criminals, who make a deliberate decision to commit a crime, or fictional murderers on Columbo, but not most real-life murderers. Most real-life murderers are not like those we see on Columbo and other whodunit shows. For one thing, they are very seldom highly intelligent and successful men and women.
Second, and more importantly, once again contrary to microeconomics, there is something worse than death. From an evolutionary psychological perspective, life – and everything in it – is a means to the ultimate end of reproductive success. So death is not the worst thing; complete reproductive failure is. If some men face a very dim reproductive prospect and a distinct possibility of ending their lives as total reproductive losers, it makes perfect evolutionary sense for them to be violent toward other men, in an attempt to eliminate them as intrasexual rivals for mates by killing or maiming them. It also makes perfect evolutionary sense for men who cannot gain legitimate reproductive access to women to attempt to do so illegitimately through forcible rape. This is why most criminals – especially murderers and rapists – are poor, uneducated men of few means and low social status who face very grim reproductive prospects.
Such men may end up being total reproductive losers, by being executed by the state, if they are violent and killed other men or raped women. But they will definitely end up being total reproductive losers if they do not kill or rape. Under such circumstances, it makes perfect evolutionary sense for some men with grim reproductive prospects to attempt to improve their reproductive opportunities by being violent toward other men in order to eliminate them as intrasexual rivals, or by raping women in order to gain illegitimate reproductive access to them.
I enjoy watching science evolve as new theories break old orthodoxies. One of my favourite books is Thomas Kuhn's The Structure of Scientific Revolutions. That book was written 50 years ago, but it is still relevant and well worth reading. It was my first introduction to how established scientists scoff at young upstarts and pretend that the new ideas are ridiculous and wrong-headed. All too often an establishment is comfortable in fortifying their position with platitudes while ignoring paradoxes. The rebellious upstarts have taken the paradoxes seriously and have discovered a new paradigm on which to recontruct the science on improved foundations. It is a wonderful, and compelling story. Read the book!