Malaysia: Scientists unlock secret of proboscis monkeys

The Star 22 Feb 18;

KOTA KINABALU: There is a secret to Sabah’s iconic male proboscis monkeys – when they become bigger, so will their body and testicles.

But more importantly, the males with a bigger nose can attract more females.

According to a scientific study, there is a clear link between the nose sizes of the males and the number of females in their harems.

The study was jointly carried out by scientists from the Sabah Wildlife Department, Danau Girang Field Centre, Cardiff University and Kyoto University.

During this study, morphological measurements and behavioural observations in free-ranging proboscis monkeys were carried out in the Lower Kinabatangan Wildlife Sanctuary, Dr Ikki said in a statement.

They also recorded the vocalisations of male and female proboscis monkeys at three different zoos – the Yokohama Zoo in Japan, Singapore Zoo and Lok Kawi Zoo in Sabah.

“Based on the collected data, we tested the correlations between body mass, facial characteristics, testicular volume, vocalisations, and the number of harem females in captivity and free-ranging proboscis monkeys,” he said.

“In addition to finding that enlarged male noses serve as advertisements to females in mate selection, we also found that males with larger noses also tended to have larger body mass and testis. This suggests that nose enlargement is a reliable predictor of social dominance and high sperm count,” said Dr Ikki.

The proboscis monkey is endemic to Borneo and is a totally protected species in Sabah.