In the animal kingdom, males of different species have specific traits or behaviors that help them attract potential mates.
Brightly colored feathers, specific calls or songs, exaggerated physical traits, mating dances, and building elaborate nests are all ways males use to find love.
For the male proboscis monkey, its long drooping nose seems to be key in attracting females, and new research has found that the bigger the nose the better.
The study was conducted by an international team of researchers and published the journal Science Advances.
The findings prove that for proboscis monkeys, nose size matters, as larger noses are an audio-visual indicator of the male’s strength and virility.
The larger nasal passages produce deeper calls which possibly alerts females to more suitable males.
The researchers also found that male proboscis noses likely evolved as the result of male competing and female choice.
“In animals, males often have exaggerated physical traits as a consequence of sexual selection. But you can’t get any odder than the long, drooping nose of the proboscis monkey,” said Hiroki Koda, the first author of the study. “And although this unique feature has long been admired, explanations for its evolution and its ecological roles had remained unclear.”
The researchers examined and monitored proboscis monkeys both in the wild and captivity to determine how nose size indicated sexual attractiveness to the opposite sex.
The team tested to see if there was a link between large nose size and other appealing traits such as body mass, facial characteristics, testicular volume, and how many harem females there were in different groups.
“We found strong correlation between the size of an enlarged nose with physical strength — indicated by body mass — and reproductive ability — indicated by testis size,” said Koda. “The number of harem females was larger as well. To put it simply, the large nose appears to act as a ‘badge’ of strong male characteristics.”
The results are noteworthy because they provide new insight into the evolution of the male proboscis in relation to attractive physical traits.
Next, the researchers hope to further examine proboscis monkeys and discover how their large nose attracts mates within the social framework of the species.
Image Credit: Kyoto University/Matsuda Lab