Scent molecules help monkeys find mates

Mating in simians is determined by highly specific scent molecules called pheromones, which help in hunting a suitable partner, a new study has revealed.

However, human begins are not that lucky when it comes to pheromone signals. According to Jianzhi George Zhang, evolutionary biologist at the University of Michigan, colour vision puts human pheromones out of business.

Although humans and apes still carry genes that create pheromone receptors in the noses, these genes have mutated to the point that they are merely pseudogenes and are not functional any more.

Using the genes of people and primates to crack this intriguing puzzle, Zhang presented his findings in the online Proceedings of the National Academy of Sciences.

Female New World monkeys have full colour vision because females have two X chromosomes that harbour both red and green colour vision genes. But since males have only one X chromosome, it leads to New World males having only one copy of either the red or green gene, resulting in color-blindness.

A pheromone attaches to a water molecule, drifts about in the air currents and finally lands on the proper receptor in someone else's nose. The receiver can't immediately be sure about the sender and its origins, but sexual swelling helps everyone in the troop to precisely locate the signal, even at a significant distance.

Sexual swelling occurs in about 10 per cent of all primate species, but only in the Old World species of Africa and Asia, which is where humans probably originated, as well.