Vervet monkeys ( chlorocebus pygerythrus ) that carry certain gastrointestinal parasites do not groom others as much as those without the parasite. This is the conclusion reached by Brandi Wren, a researcher at the Department of Anthropology at Purdue University (United States) after studying the social grooming of green monkeys and its relationship with parasites in South Africa.
The results, which were published in the journal Plos One , showed that monkeys carrying certain parasites do not groom their companions as much as those without the parasite, and that the routes of transmission may not be as clear as biologists believe in the actuality.
New avenues for research
Vervet monkeys share numerous similarities with humans. In addition to sharing more than 90% of the DNA with humans (something that happens with all species of primates) it is also known that these monkeys can suffer diseases or alterations very similar to people, including anxiety or hypertension among others.
Therefore, this study could open new avenues of research on various aspects of human biology. In fact, as the researcher Wren argues, this study shows some of those similarities with humans because, when we feel sick, we also want to be alone. Thus, there are many similarities in how monkeys and humans interact within their own groups.
Relationship with parasites
Wild animals, such as monkeys, are often carriers of parasites. Biologists have long assumed that these infections do not significantly affect the health of the animal. What is most surprising, however, is that the parasites researcher Wren was studying are not transmitted through social contact.
These gastrointestinal parasites are generally transmitted through substances in the environment or contaminated soil. However, research shows that they can significantly affect an individual’s social behavior.
The team of scientists followed three troops of vervet monkeys across South Africa. By cataloging the monkeys’ interactions and toilet habits and cross-referencing infection information from fecal samples, they were able to conclude that infected monkeys spent less time grooming other monkeys.
Furthermore, according to the researcher, there is no way to know which monkeys are infected just by observation, as there are often no other signs of infection (beyond social behavior).
The personality of animals
This study is also important for animal researchers. In fact, more and more information on parasite load and hormonal levels is being incorporated into research on the behavior of different species.
Otherwise, scientists could misattribute behaviors to personality traits, when in fact that behavior is due to a gastrointestinal (or otherwise) infection.
