By Dr. V Ramakantha
Yongmu, meaning ‘Black Monkey’ in Manipur is an agile creature of the jungle which has remarkable capacity to swing from branch to branch with exceptional speed in the canopy of trees. Yongmu is not a monkey at all. It is an ape. Known to science as Bunopethicus hoolock, it is the sole representative of apes in the Indian subcontinent.
Unlike monkeys, apes do not have a tail. They have an upright body, and have opposable thumbs on the palms of their hands, and hence, among the mammalian world, belong to an exclusive group alongside the human beings. In the tree of evolution, some of the apes share with us a whopping 98 per cent of our genetic material.
There are scientists who discount these similarities of apes with human beings. They argue that the genetic material similarity has more to do with the structural resemblance of the apes with the human beings, and they are quick to point out the similarities of cytochrome C of dogs and hemoglobin of a horse with that of the human beings (cytochrome C of dogs is about 90 per cent similar to that of a human; and the hemoglobin of a horse is about 88 per cent similar). Others doubt the common ancestry with the apes as it is yet to be established by fossil evidences. Obviously, animals are not people. However, here are a few established facts about Hoolock gibbons that you may like to ponder over.
The male and female gibbons mate for life, and live in small family groups which may not exceed six members. The adult females have menstrual cycles with an average duration of 28 days. The gestation period has duration of about 7 months, after which the female gives birth to a single offspring. Young gibbons are virtually helpless, and need nursing up to two years. The young stay with their parents till they attain maturity (up to 6-8 years). When a member of the family is killed, the rest mourn for long periods. It is a different story that such is the interdependence that the loss of an adult in the gibbon family often leads to obliteration of the rest. Having observed them in captivity for over four years, I know that, like humans, they are capable of feelings, and try to understand a problem and find solutions to it.
The evergreen and semi-evergreen forests in which gibbons dwell reverberate with their high decibel prolonged calls, as the apes earmark their territory and ward off the intruders through vocalizations. The male and female gibbons combine their vacillations in intricate patterns to produce coordinated duet songs. This elaborate vocalizations called ‘songs’ is the specialty of gibbons, found neither in great apes nor in most other primates.
There are a couple of Hoolock gibbons in Manipur Zoological Garden. The male is coal black in colour, with prominent white brows, and the female is buff coloured, with a mask-like face. Both are in fine health, and brachiate from one end of the enclosure to the other to break their monotony that invariably comes with captivity. However, given proper conditions (bringing diversity in their menu, and making a false canopy under the wire mesh helps), they would breed in captivity. With very minimum effort a visitor to the zoo can stimulate the apes in to a howling frenzy, and unfortunately, most indulge in teasing the apes. It is something that comes in the way of their peaceful existence in the zoo.
Gibbons are spread over large areas, their range extending across Bangladesh, Myanmar and in Gaoligongshan Nature Reserve (southern China). In India, they were found in Manipur, Tripura, Meghalaya, Assam, Arunachal Pradesh, Nagaland and Mizoram. However, gibbons have dwindled considerably across their range, including in the Northeastern States of India, and have been extirpated from many sites. In Manipur, a couple of decades ago, they were widely distributed in the forests of Tamenglong, Churchandpur, Chandel and Ukhrul districts and in Jiribam Subdivision. There are hardly any left in the wild either in Manipur or in Nagaland.
If there are some gibbons still eking out a living on the tree tops either in Manipur or in Nagaland, please let us know.