London: The concept of the colour red being defined as a signal that suggests that a woman is ready to mate is not limited to the human species. The 'red effect' sparks a similar interest in female monkeys as well, suggesting that it is somewhat of an evolutionary mechanism.
Previous research shows that the colour red in a mating context makes people attracted towards each other and in the fighting context makes people seem more threatening and angry.
"We asked: Is it triggered simply by repeated cultural exposures or is there a biological basis that may help explain why the colour tends to amplify human emotions?" said Benjamin Y. Hayden, professor in brain and cognitive sciences at the University of Rochester.
The researchers conducted two trials involving 1,000 rhesus monkeys from the Cayo Santiago field site in Puerto Rico.
In the first trial, the researchers displayed sequential images of male hindquarters (the hind legs and adjoining parts of a quadruped) surrounded by frames of red or blue to adult monkeys of both sexes.
The researchers found a significant female bias toward the images of male hindquarters but only when a red frame surrounded the image.
"To our knowledge, this is the first demonstration of an extraneous colour effect in non-human primates," Hayden added.
In a second trial, the researchers displayed images of female hindquarters surrounded, again by either a red or blue frame.
Female monkeys did not show a preference for other female hindquarters regardless of the colour.
But male monkeys too did not show a preference for the female hindquarters either even when surrounded by the colour red.
"One possibility for this is that the reproductive state of females is reflected in facial colour changes rather than changes in the hindquarters," the researchers said.
The study appeared in the journal Evolution and Human Behavior.