A research group led by Assistant Professor Hiroki Koda of the Primate Research Institute of Kyoto University and Associate Professor Ikki Matsuda of the Primate Research Institute of Chubu University has accumulated ecological and morphological data on Tengu monkeys for more than 10 years. For the first time in primates, the evolutionary scenario of "advantageous" was demonstrated empirically.
According to evolutionary advocate Darwin, the flashy and decorative form of males is believed to have evolved through sexual selection in the male conflict over females.It is also said that in primate societies where complex social relationships such as the formation of harem-type herds exist, the flashy morphological decoration of males tends to be prominent.
The group investigated the correlation between the nasal morphology of male wild proboscis monkeys in Malaysia and other measures.As a result, male nose size, body weight, and testicular volume showed a positive correlation.In addition, when the correlation between the size of the male nose and the number of females belonging to each harem was examined, it became clear that the number of females in the harem was higher in males with larger noses. ..Furthermore, when the correlation between the voice data of male proboscis monkeys collected from domestic and foreign zoos and the morphology of males was investigated, the low voice of males was found to be physical strength (size of physique) and high fertility. It shows (the size of the testicles) and succeeded in showing that it may be a great weapon to attract females.
This research is the first achievement of a primate that empirically proposed an evolutionary scenario that accelerates "masculinity."
Paper information:[Science Advances] Nasalization by Nasalis larvatus: Larger noses audiovisually advertise conspecifics in proboscis monkeys
