Previous studies have shown that women who take testosterone see an improvement in their spatial navigation skills, says Justin Rhodes, professor of psychology at the University of Illinois, who led the study.
Some argue, for example, that males' slight, but significant, superiority in spatial navigation over females is probably "adaptive", meaning that during evolution, the trait gave males an advantage that led them to have more offspring than their peers, the journal Quarterly Review of Biology reports.
The researchers, led by Rhodes, reviewed 35 studies that included data about the territorial ranges and spatial abilities of 11 species of animals, including cuttlefish, deer mice, horses, humans, lab mice, meadow voles, pine voles, prairie voles, rats, rhesus macaques and talastuco-tucos (a type of burrowing rodent).
Rhodes and colleagues found that in eight out of the 11 species, males demonstrated moderately superior spatial skills to their female counterparts, regardless of the size of their territories or the extent to which males ranged farther than females of the same species, according to an Illinois statement.
The findings lend support to an often-overlooked hypothesis, Rhodes said. The average superiority of males over females in spatial navigation may just be a "side effect" of testosterone, he said.
Researchers tend to overlook the fact that many physical and behavioural traits arise as a consequence of random events, or are simply side-effects of other changes that offer real evolutionary advantages, he said.