Monkeys prove it

Apr 5, 2008 07:57 GMT  ·  By

It is largely believed that boys are educated to adopt male values: in movies or video games, the male heroes are killing machines with muscular hypertrophy that solve their problems through force, annihilating their opponents. Boys are punished more harshly than girls are, and parents expect them to be tough, protective while male friends reject those that cry. Whereas, girls are expected to be sensitive.

There are so many psychologists insisting that sex behavioral differences, like the tendency of boys to prefer toy soldiers and of girls to prefer dolls, is caused by social factors, not innate ones. But this concept ignores all the studies showing different brain structures and behaviors between the sexes. And the brains are sexualized from the womb. Boys are better in visualizing three-dimensional objects or read maps, labyrinths and diagrams.

Now, a new research made on rhesus macaques supports the idea that boys playing with car toys is something innate, not acquired.

"This could mean that males, whether human or monkey, have a biological predisposition to certain toys," co-author Kim Wallen, a psychologist at Yerkes National Primate Research Center in Atlanta, Georgia, told NewScientist.

The team investigated 11 male and 23 female rhesus monkeys. Generally, males preferred to play with wheeled toys rather than plush dolls, while females played with both types of toys.

"Social factors undoubtedly influence children's preferences, but in general boys tend to be pickier with toys than girls," said Wallen. Monkeys could not be pressured by social pressures in choosing their toys. And the majority of the individuals were juvenile (aged one to four years), but the group also included sub-adult and adult macaques.

Two toys, one wheeled and one plush, were located 10 m (33 ft) apart.

"At first the monkeys formed a circle around a toy, but eventually one would snatch the toy and run off. Other monkeys soon joined in the fun," said Wallen.

Based on video recordings, the team assessed how long each macaque spent with plush or wheeled toys. Males clearly preferred wheeled toys, while the females had no preferences.

"The plush and wheeled categories served as proxies for feminine and masculine, but other toy characteristics, such as size or color, might explain the male's behavior. Or the male monkeys might seek out more physically active toys," said Wallen.

This research supports the results of another similar research made on green vervet monkeys at Texas A&M University in College Station. "There is likely to be a biological tendency that is amplified by society," Gerianne Alexander, lead author of the vervet monkey study, told New Scientist.

Some men-women brain differences

In women - the corpus callosum that connects the two brain hemispheres, allowing their intercommunication - is much wider. That's why women have their brain functions more distributed, while men have a more "asymmetrical" brain, with more specialized areas and, for example, a lesion on the left hemisphere, which can induce speech loss, is more devastating for men.

But this also explains why women have better concrete thinking, while men a better abstract one (and are better at chess and composing music); and why women prefer to repeat loudly what they are learning, while men learn in silence.

The female brain is 11% lighter than the male brain, still IQ coefficients of the women are similar to those of the men. That's because men have less gray matter (that processes information) and more white matter (that transmits information). This explains why the female brain learns easier and men have more motor ability.

But why do women express their emotions better?

That's because their emotional thinking centers are close to the speech centers, so they can verbalize better their emotions. Men have a simpler limbic system, and their emotions are bound to action.