For primates, parasites are the cost of learning

"Our results support the idea that exploratory and social behaviors expose primates to specific kinds of parasites," says Simon Reader. (Credit: Will Keightley/Flickr)

The same things that advance civilization, such as learning from others and innovation, have costs as well as benefits.

A new study sheds light on how one particular cost—increased exposure to parasites—may affect cultural evolution in non-human primates.

The results suggest that species with members that learn from others suffer from a wider variety of socially transmitted parasites. On the other hand, innovative, exploratory species suffer from a wider variety of parasites transmitted through the environment, such as in the soil or water.


“We tend to focus on innovation and learning from others as a good thing, but their costs have received relatively little attention,” says McGill University biologist Simon Reader, coauthor of the study in the Proceedings of the Royal Society B.

“Here, we uncover evidence that socially transmitted pathogen burdens rise with learning from others—perhaps because close interaction is needed for such learning—and environmentally transmitted pathogen burdens rise with exploratory behavior such as innovation and extractive foraging.”

Chimpanzees, for example, live in groups and have a wide range of such behaviors, such as digging for food underground or eating new kinds of insects.

Previously, studies have not been able to determine whether costly parasites force primates to engage in more exploratory behavior—by diversifying food sources, for example—or whether exploratory behavior leads to their having more parasites, Reader notes.

“Our results support the idea that exploratory and social behaviors expose primates to specific kinds of parasites.”

“The findings also lead to questions about how people and other primates have developed solutions to minimize these parasite costs—such as eating medicinal plants—and may help us better understand how the processes underlying human culture arose,” Reader says.

The research team, led by Collin McCabe of Harvard University and Charles Nunn of Duke University, based their analyses on databases obtained by surveying thousands of articles on primate behavior and parasites.

Funding for the research came from the National Science Foundation, the Natural Sciences and Engineering Research Council of Canada, and the Netherlands Organisation for Scientific Research.

Source: McGill University