Link between rape and pregnancy

It may be that ovulating women attract unwelcome attention

Scientists have made a disturbing finding about rape which they believe may explain why the crime has been so common throughout history.

They have found that a single act of rape may be more than twice as likely to make a woman pregnant than a single act of consensual sex.

This suggests, they say, that in a strictly biological sense, rape is a successful way for a man to spread his genes.

In our experience rape is used in domestic violence to exert power and control, and not necessarily to spread one's genes

Myra Johnson

But such a theory fails to take account of either the emotional trauma that rape causes, or the fact that for rape to be a successful evolutionary strategy the benefits of the crime have to outweigh the potential costs for the rapist if he is caught.

Psychologists have also warned that it may be misinterpreted by those seeking to justify the unjustifiable.

Violence study

New Scientist magazine reports that researchers Jon and Tiffany Gottschall, from St Lawrence University in Canton, New York, looked at data from a major study of violence against women.

They found that, of 405 women who had been raped between the ages of 12 and 45, some 6.4% became pregnant.

When women who had been using some form of contraception were removed from the calculation, the figure jumped to nearly 8%.

They compared this finding with a separate study which found the proportion of women in a similar age group who got pregnant from a one-night stand or other one-off act of consensual sex was just 3.1% despite the fact the women were not taking precautions.

The Gottschalls believe one possible explanation is that women feel more attractive and sexy when ovulating and unconsciously give off signals that rapists might pick up.

Another possible explanation is that rapists target attractive and healthy-looking women.

Difficult conclusions

Rape is complex behaviour which is often associated with power, control and sadism

Ged Bailes

Ged Bailes, head of forensic clinical psychology at the Norvic Clinic in Norwich, told BBC News Online, it was very difficult to draw any firm conclusions from a one-off study.

He said: "Rape is complex behaviour which is often associated with power, control and sadism.

"How do things like that fit into an evolutionary theory? And if this was the case why would some rapists want to kill their victim?

"We have to be very careful about making inferences of this type because there is a danger that they will reinforce some people's views about the myths surrounding rape."

Myra Johnson, communications manager for the Women's Aid Federation, a charity which helps women who have been the victims of domestic violence, warned against drawing the wrong conclusions from the report.

She said it was vital that any notion of a possible evolutionary basis for rape should not detract from the personal responsibility that a rapist had for the devastating impact of his actions.

She also told BBC News Online: "In our experience rape is used in domestic violence to exert power and control, and not necessarily to spread one's genes."