Studying our prime relatives


We are continuing to the fourth article of series of articles on anthropology, ‘Anthropological Gleanings’ this week, with main focus on the sub discipline of physical anthropology, primatology. Primatology can be simply defined as the scientific study of primates. In fact, it is a diverse discipline at the boundary between zoology and anthropology, and researches are being carried out in academic departments of anatomy, anthropology, biology, medicine, psychology, veterinary sciences and zoology, as well as in animal sanctuaries, biomedical research facilities, museums and zoos. Thus, this subject area is vast, diverse and of course very interesting. Primatologists study both living and extinct primates in their natural habitats and in laboratories by conducting field studies and experiments in order to understand aspects of their evolution and behaviour.

Speaking of the subject, its applications and the complexities, the head of the Department of Anthropology, Faculty of Humanities and Social sciences, University of Sri Jayewardenepura, Prof. Charmalie Nahallage, shared her insights with Ceylon Today.

Who are the ‘primates’?

“As it was mentioned earlier too, we study the evolution and the behaviour of the primates. But who are these primates is a question. So, before explaining who these primates are, let me take an approach to the background of this idea of primatology. As it is commonly known, we, the humans are also considered as animals in biological anthropology and in precise, we are mammals. If I define who mammals are, they basically are the animals who suckle breast milk from the mother during the infancy. They have a special gland called mammary glands to produce milk.

These glands are located in the breast overlying the pectoralis major muscles, and present in both sexes, but usually function only in the females. Starting from humans, domestic animals such as cats, dogs and cows, wild animals such as apes, monkeys, cheetah and chimpanzees, aquatic animals such as dolphins and whales and a plethora of other animals too fall into the category of mammals. Thus this group is diversely vast and needs to be categorised into sub-groups based on more subtle and distinctive features, for the purpose of study. Ergo, there are 17 sub-groups of mammals, known as ‘orders’ and primates are one of those orders,” she exemplified.

Elaborating further, Prof. Nahallage mentioned that though humans also fall into the order of Primates, they are not the only species belonging to it. According to her, there are other animal species in this order including lemur species whose natural habitat is Madagascar, lorises called Unahapuluwa in Sinhala, tarsiers, monkeys (both New World Monkeys native to Americas and Old World Monkeys indigenous to Africa and Asia), and apes (chimpanzees, Gorillas, Gibbons and Orangutans). These are called non-human primates.

Primates in Sri Lanka

“Sri Lanka is a biodiversity hotspot. Despite the small land area of the country, there is a rich array of flora and fauna found in Sri Lanka. So, we can find several non-human primates here also. One of them is macaque commonly known as Toque Macaque, commonly known as Rilawa in Sinhala. There are three sub species of macaques; the dry zone sub species, wet zone sub-species, and the highland sub-species. Then there are two types of langurs in Sri Lanka as Purple-faced Leaf Langur and Grey Langur, and the Purple-faced Langur have four sub-species known as Southern Purple-faced Langur, Western Purple-faced Langur, Highland Purple-faced Langur, and the Northern Purple-faced Langur, distributed in various parts of the country as mentioned.

The Grey Langur is commonly found in the dry zone of the country and any sub-species of them haven’t been identified yet. The other non-human primate species is lorises or commonly known as Slender Loris. There are dry zone Slender Loris (Loris lydekkerianus) and the wet zone Slender Loris (Loris tardigradus). All the primates of Sri Lanka are endemic to the country therefore it is important for us to protect and conserve these animals to protect the bio diversity in the island” said Prof. Nahallage.

The field of Study

“Humans are of course very close to these non-human primates and lots of interactions take place between them. So, social scientists as well as the natural scientists have been studying these primates since a long time back. The discipline of studying primates is known as primatology nowadays and in fact, it is relatively new discipline of study,” she took an initiation to describe the study field.

Prof. Nahallage further mentioned how the primates have been studied earlier by various scientists and experts in numerous fields such as psychology and zoology to understand the behaviours of the humans, their psychology and social behaviours, though, according to the professor, these studies have been carried out in laboratories where the animals were caged. Therefore, the studies were not completely successful since the behaviour of primates in captive environment is different from that of in their natural environment. “Hence, the researchers identified the need of studying the primates in the natural habitats during the 1930s. These studies were first tried in African countries but with little success. Anyways, later on, the field studies of primates had been carried with much success, by scientists around the world such as from Japan, USA and UK and later by many range counties,” she added.

At present scientists throughout the world study many important aspects of primates such as behaviour, anatomy, genetics, evolution, diseases and conservation.

An important topic that is related to the wellbeing of the humans and primates alike are the diseases that could transmit between primates and humans. The disease transmission could occur in many ways such as by eating meat of the infected primates, working at laboratories where primates are housed or at zoological gardens, having primates as pets and eating food that are contaminated with primate faeces and so on.

Zoonotic diseases and the primates

“Because of our close interactions with animals, and the similarity between us and some of these animals, there is a risk of transmitting various types of diseases from animals to humans. These diseases are called zoonotic disease or simply zoonosis. In the same token, there are anthropozoonotic diseases as well. They are the diseases transmitted to animals from humans. This risk is even higher when it comes to primates as they share very similar physical and biological characteristic with humans,” Prof. Nahallage explained.

There are many who study these zoonotic and anthropozoonotic diseases at a larger scale, because it is very important for the welfare of both humans and animals alike. It is very crucial that we identify the diseases and discover cures for them. Speaking in this regard, Prof. Nahallage shared her insights. “One of the most significant zoonotic diseases in the recent history is the Simian Immunodeficiency Virus (SIV) a virus that naturally occurs in African nonhuman primates and is the source of the human immunodeficiency virus. This virus was first found in old world monkeys and apes of Africa and then transmitted to humans. Initially humans must have contracted the virus during hunting or other sort of interaction. Then, the virus had spread among humans and evolved into the present Human Immunodeficiency Virus (HIV). Nevertheless, it is not from the monkeys or apes that this disease is transmitted now, but from human to human.

“However it is very important to note that these diseases are not transmitted from all the animals but only from the infected animals that harbour the parasites,” she emphasised.

According to Prof. Nahallage, there are several ways in which the disease agents (virus, bacteria, protozoans, helminthes and fungi) could get transmitted from animals to humans or vice versa;

Hunting is one major way of transmission since during the hunting the body fluids of the animals could get in contact with the hunters’ skin. And if parasites are present then they could enter the human body through skin lesions and cuts.

Bush meat trade and consuming under-cooked meat are also ways of transmission. In that case, the parasites enter into the body through the digestive system.

Having primates as pets is also another means of transmission. Though it is not recommended in Sri Lanka to keep primate as pets, there still are people who keep monkeys as pets or use them as entertainers. These close interactions pave the way for the transmission of parasites both ways.

Tourism especially ecotourism, if not conducted in proper manner, could be a reason for the transmission of zoonotic diseases. When people feed monkeys they could get exposed to the parasites in these primates’ saliva or when people go to worship the religious places such as Polonnaruwa, Anuradhapura and so on, they could step onto primate faeces by accident and parasites such as hookworms could enter into human body.

Sometimes, people tend to consume fruits that have been half eaten and dropped by primates. Further, at some occasions the home garden crops could get contaminated by primate faeces and urine. So, if people eat them without cleaning properly, there of high risk of disease transmission to humans through these contaminated food and water.

A moral dilemma

“The biomedical research and studies done by scientists have immensely contributed for the betterment of the society in means of physical and mental health. So, we cannot deny the significance of these researches at any length, yet there is a concern in the society against using animals for scientific testing and research studies. Many animal rights protectors have stepped forward to talk against the unethical use of animals in testing cosmetics and medicine. Nonetheless, the question is whether we can simply stop them altogether.

It is through these studies that we have discovered cures and immunisation vaccines for various fatal diseases and epidemics such as measles, ebola, small pox, COVID-19, and monkey pox, the most recent virus that managed to ring alarm bells around the world. At the same time, we cannot deny the rights of the animals too. Though as anthropologists who perceive the world from a humane perspective, we have to consider the rights of the animals as well. As such we are in a moral dilemma in this regard. However, as anthropologists we have to find ways to look into the welfare of the animals while  conducting these studies as they are conducted for the betterment of both humans and animals,” Prof. Nahallage concluded the discussion.

Further, Prof. Nahallage, as the Head of the Department, invite all the students as well as other stakeholders who are interested in anthropology to join with them through the official Facebook page Anthropology crew of University of Sri Jayewardenepura or the university website on behalf of the Department of Anthropology of University of Sri Jayewardenepura, since they are planning to conduct many interesting events and programmes related to anthropology and related fields, in future.

By Induwara Athapattu