Sumatran orangutans
Conservationists discovered a population of world's rarest orangutans in the island of Borneo.Reuters

Sumatran male orangutans delay puberty to become stronger than the other dominant males and to attract the opposite sex, according to a study.

Male orangutans can reproduce at the age of 15, but Gauri Pradhan and her colleagues from the University of South Florida in Tampa have found out that the Sumatran orangutans in the Indonesian islands have been cleverly able to hold their puberty for extra 10 years.

Male orangutans in the Sumatran islands of Indonesia have learnt to successfully delay their puberty until they grow secondary sexual characteristics like cheek flanges and muscle mass to attract the females.

They also grow long hair on the arms or back and also develop larger throat pouches to attract females for mating. 

Gauri and her team compared two different type of adult males - one with the secondary sex and the other without - having different mating strategies. 

They collected data and built mathematical models. Based on their mathematical models, the researchers learnt that the Sumatran male orangutans had a typical way of delaying their growth. However, such delays are found to have been less common among their cousins, the Bornean orangutans.

The Sumatran orangutans is said to be delaying the puberty until they become stronger to overthrow the other dominant males. After this, they reach sexual maturation and are able to monopolise the female orangutans for weeks.

The researchers also found that those orangutans, which get matured at a later stage, are also dominant over other males.

So far, it has not been clear whether these orangutans have deliberately delayed their puberty and if so, how they do it. Although the delay in attaining puberty can help these orangutans in their reproductive system, the scientists believe that the delay in sexual maturation have a link with early deaths in the primates.

"Pronounced developmental arrest is linked to very low adult mortality, which explains why it is so limited in its taxonomic distribution," Medical Daily quoted the researchers as saying.

The study has been published in the American Journal of physical anthropology.