Men are much more likely than women to use fists to settle disputes not because of the different ways girls and boys are reared, but for biological reasons, says a new study in the journal Science.
In short, it’s no fluke more little boys come home from school with bloody noses than girls, said the lead study author, Dr. Ruben C. Gur of the University of Pennsylvania Medical Center.
In the study, radioactive tracers were injected into 37 men and 24 women in a dimly lit room, and brain activity was monitored. They were told to stay quiet and relax, which was harder for men.
Brain activity was identical in both sexes except in areas involved in emotional and cognitive processing, he said.
The temporal limbic system, which is thought to control action-oriented responses including violence, was more active in men. A less primitive and more refined part of the brain called the cingulate gyrus, which controls symbolic responses such as language, was more active in women.
“Males showed more activity in the part of the brain that we share with reptiles and beasts of prey, whereas activity in women was greater in parts of the brain associated more with communication,” Gur said.
Other studies have shown differences in emotional processing between the sexes, but Gur said this was the first to find physiologic differences.
“The results are significant, because the probability this is a chance event is less than one in 10,000,” he said.
Scientists praised the study.
“This is clearly another important piece to the pattern that there is a strong possibility some differences between the sexes are preprogrammed,” said Dr. Sandra Witelson of McMaster University in Ontario.