Monkeys are less comfortable with each other when dealing with an infection, the study reveals

Social care plays an important role in the society of vervet monkeys, helping with specific social ties and increasing the chances of the animal reproducing. However, research by anthropologist Brandi Wren reveals that monkeys suffering from certain gastrointestinal parasites may not participate in care like monkeys without infections. Credit: Purdue University / Brandi Wren

Brandi Wren studied social distancing and infections before strips of the mask appeared on the store floor and plastic partitions were erected in the post office.

Wren, a visiting scientist from the Department of Anthropology at Purdue University, spent a year studying the carcasses of wild vervet monkeys in South Africa, monitoring their social care behavior and parasite burden. Its results, some of which were released on Wednesday (April 21st) in PLOS ONE they have shown evidence that monkeys carrying certain gastrointestinal parasites do not groom others like those without parasites, and that transmission routes may not be as clear as biologists think.

With implications for animal behavior and human health, Wren’s results open up new avenues for research and new ways to consider old research. Vervet monkeys share striking similarities with humans. In addition to sharing more than 90% of human DNA – something that applies to all primate species – vertebrate monkeys are also known to show conditions that are better known in humans than in other animals, including anxiety and hypertension. Biologists have discovered that studying the physiology, genetics and behavior of vervet monkeys can shed light on some aspects of human biology.

“We have so many similarities in behavior; the roots and nuances of social behavior tend to be similar in all primates, especially from apes to humans,” Wren said. ‘This study shows some of those similarities while, when we’re sick, we don’t want to talk to anyone.’ You can rub my back, anything, but I really want to be alone. ‘ We see a lot of similarities in the way humans and monkeys communicate within their groups. “

Monkeys are less comfortable with each other when dealing with an infection, the study reveals

Brandi Wren, a visiting scientist at Purdue University, spent a year following the carcasses of vervet monkeys through the Loskop Dam Nature Reserve in South Africa to better understand the interactions between social care and gastrointestinal parasites. Credit: Purdue University / Brandi Wren

Wild animals usually carry a nominal load of parasites. Biologists have long assumed that these infections are harmless – that they are asymptomatic and do not significantly affect the health of the animal or its appearance. Even more interesting is that the parasites Wren studied – whips or trichuris – are not parasites that usually spread through social contacts. These are gastrointestinal parasites that usually spread with contaminated soil or substances in the environment. But Wren’s research shows that they can spread through social contacts and can significantly influence an individual’s social behavior.

“Infected people show a bit of lethargy, but interestingly, they still allow other individuals to groom them; they just don’t groom others,” Wren said. “They also don’t cuddle as much with other monkeys. They just don’t seem to feel well.”

Wren and her team followed three troops of vertebrate monkeys, Chlorocebus pygerythrus, through their entire home in the Loskop Dam Nature Reserve in South Africa. By exhaustively cataloging the interactions and habits of grooming individual monkeys and cross-references with data on infections from fecal samples, Wren and her team were able to separate that whip-infected monkeys spent less time editing other monkeys. They accepted grooming — when offered — but did not offer to groom their comrades in the army.

Wren notes that this difference in behavior is not so sharp that it is noticeable only by observing monkeys. Only by rigorously observing grooming behavior, by exhaustively studying fecal samples, and analyzing these results in relation to each other, could Wren decode this connection.

Monkeys are less comfortable with each other when dealing with an infection, the study reveals

Studying vertebrates can help scientists understand human biology. Vervet monkeys share more than 90% of their DNA with humans and show conditions that are better known in humans than in other animals, including anxiety and hypertension. Credit: Purdue University / Brandi Wren

“There’s no way we could just know by observation which monkeys are infected,” Wren said. “There are no other signs of infection other than social behavior. And change is often so difficult to detect. It takes a long time to track an individual and collect data to see it. The effect lies in this complex network of interactions.”

Wren argues that her discovery is important for animal researchers to keep in mind. As animal personality studies began to gain popularity, she stressed the importance of including information such as parasite loads and hormone profiles in those studies. Otherwise, biologists could mistakenly attribute behavior to personality traits when the active infection is really to blame.

“Some people look up and think, ‘God, this guy is a jerk! Always let everyone dress him up, but he doesn’t dress up anyone else!'” Wren said. “What we attribute to a personality or attitude can only be because it has a gut full of parasites.”

Wren draws parallels between troop behavior and human behavior during a pandemic. Like monkeys, humans crave social contact, albeit more in the form of handshakes, heels, and hugs. Like monkeys, humans can spread disease through social contacts and tend to withdraw a little during illness. Unlike monkeys, however, humans understand infection, hygiene, and the importance of reducing contact or increasing cleanliness.

“All of these social behaviors affect health on a practical level,” Wren said. “We know that COVID-19 is spreading by close social contacts. The fascinating thing about studying other species and one of the reasons for observing and understanding them is that we are always learning new things. One can always learn more. Even when looking at previous research, even when we thought we understood the results, we still might not know the whole picture. ”


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More information:
PLOS ONE (2021). DOI: 10.1371 / journal.pone.0240872

Provided by Purdue University

Citation: Monkeys are less pleasant to each other when dealing with an infection, reveals a study (2021, April 21) taken on April 21, 2021 from https://phys.org/news/2021-04-monkeys-cuddly-infection. html

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