In a fascinating scientific discovery, researchers have found that the orangutans of Sumatra in the Indonesian islands have found a way to hold off their sexual maturity for up to ten years. This delayed development allows them to mature only as they are old enough and strong enough to fight off stronger males. As far as researchers can tell, no other primate species, even the orangutans’ cousins in nearby Borneo, are able to do so.
Gauri Pradha, a University of South Florida researcher, found with her team that these orangutans can hold off the growth of their secondary sexual features for as long as ten years. Typically, male orangutans are able to reproduce at 15, but they won’t attract female attention until they have their secondary sexual characteristics which include cheek flanges and increased muscle.
What the researchers found to be truly amazing was that the sexual development of the secondary traits was delayed only in orangutan groups where a few dominant males controlled all of the females. Such arrested development wasn’t documented for groups of orangutans in Bornean where male orangutans didn’t monopolize individual females.
In the troops in Sumatra, the orangutans would delay their development until they had enough strength to depose the dominant males – then they would quickly reach sexual maturity.
Researchers still do not know how they are able to control their sexual maturation and whether or not they do so consciously.