Latest science research
The pros and cons of grooming in primates Plus How crows store tools
Agood social life has so many upsides that the drawbacks are rarely considered. But, while grooming among primates enhances social cohesion and promotes hygiene, new research has demonstrated that it comes at a cost.
“Many studies proclaim the benefits of grooming,” said Thomas Gillespie, who led the work on Colombia’s brown spider monkeys. “But there’s been almost no examination of the other side of the story.”
While grooming strengthens social bonds and controls external parasites, it demands physical contact sufficiently intimate to expose the monkeys to other sources of infection, particularly intestinal worms.
Gillespie’s study, based on recording social interactions and collecting faecal samples, showed that grooming does indeed increase the risk of infection. “We could even distinguish between the impact of grooming and being groomed, and clearly the strongest risk for transmission is to whoever is doing the grooming,” Gillespie told BBC Wildlife.
The findings have intriguing implications for social etiquette. The team is now trying to establish whether monkeys avoid grooming individuals who show signs of infection, for example.
There might also be social pressures for subordinate animals to groom superiors despite the risk to their own health. But because spider monkey society is not particularly hierarchical, the researchers are looking to chimpanzees for the answer to that question: “Chimps operate in a strong hierarchy, which will allow us to establish how much choice they have in the process of grooming.”
Meanwhile, in a separate study of the wolves of Yellowstone NP, researchers have found that the impact of parasitic infections is mitigated in larger social groups – mange-infected wolves are five times less likely to die if they belong to a large pack. And their presence seems to present no danger to the rest of the group, though we don’t yet know why.