Did we really evolve domestic violence? We don’t know yet | Innovation
Why is domestic violence so horrifyingly common around the world? According to a study out today, men who are violent towards their partners have more children in societies without birth control. This implies that evolution favours domestic violence – but can that really be true?
We have been here before. Some evolutionary psychologists have long argued that domestic violence is a behaviour that has evolved because it benefits males. However, the claim is usually that the reason for the violence is to ensure that women are faithful. The new study suggests the key factor is instead the number of children.
The researchers studied the Tsimane people of Bolivia, who have a pre-industrial culture with no access to contraception. Shockingly, 85 per cent of women reported violent incidents.
The team found that women were more likely to give birth in a year in which their partner was violent towards them. While the team did not explore the reasons for this, the implication is that men have evolved to use violence, or the threat of violence, to force their partners to have sex with them – that is, to rape them.
“Intimate partner violence may persist as an evolutionary strategy to enhance male fitness,” writes Elizabeth Pillsworth of California State University in an accompanying perspective piece.
All about control?
This is an idea both sexes will find repulsive, for many reasons. One fear is that some abusive men might wrongly seize upon research like this as a defence – “evolution made me do it”. There is reason to worry: in 2009 a judge in Italy cut the sentence of a man convicted of murder after learning he had gene variants linked to violent tendencies.
Worse still, a few men might conclude that this is how they ought to behave. Just look at how the idea of the survival of the fittest has been misused to justify racism and genocide.
That said, the argument that men that abuse their partners have more children is rather similar to the one that some feminists have long made, that violence towards women is all about control. And distastefulness is not itself a reason for rejecting any hypothesis.
No conclusive evidence
The hypothesis is not implausible. In animals, violence to females can boost reproductive success, and the ubiquity of domestic violence in human cultures suggests there could be some deep-rooted reason for it.
Being plausible, though, does not make something true. This study of the Tsimane involved just 105 women and was based on interviews asking about past events – a method of reporting that is known to be unreliable. It is very far from being conclusive evidence of an evolutionary link – as team member Jonathan Stieglitz of the University of Toulouse in France is the first to acknowledge.
“It would be wrong, based on our study, to say that evolution would favour intimate partner violence,” he says.
To show this more convincingly, a study would have to demonstrate that the children of abused women go on to have more children themselves. It would also be necessary to show that there are gene variants that predispose men to domestic violence rather than violence generally, and Stieglitz does not think they exist.