According to new research published in the Journal of Animal Ecology, physical contact may be good for your health. Well, at least if you’re a lemur.
Scientists have found a direct link between physical contact and gut bacteria in red-bellied lemurs (Eulemur rubriventer). The study aim was to better understand causes of diversity within the animal’s gut microbiome. These communities of belly bacteria play a key role in health by aiding digestion and fine-tuning immunity.
The study results showed that social groups of lemurs had markedly similar gut microbiomes and even within groups, individuals shared more similar gut community with their closest friends. Red-bellied lemurs are a very tactile, socially-bonded species that live in small family groups of two to eight individuals, and spend a lot of time together.
Aura Raulo, lead author and graduate student at Oxford’s Department of Zoology, believes that this sociality is an important part of bacteria transfer. “In close social groups like red-bellied lemurs, social environment is key to immunity,” she said. “Animals that touch each other more tend to spread microbes, both good and bad, but eventually frequent social contact leads to a synchronised microbiome. Because microbes tune immune defence, this can be seen as a form of cooperative immunity – sharing microbial allies and enemies makes infections by opportunist pathogens less likely.”
The researchers suggest that sharing a similar microbiome within a social group may have a positive health impact, essentially harmonising the immune defence and preventing members from contracting dangerous infections. Since social bonds were associated with gut microbiota, information about gut bacteria could also be used to reconstruct the social network of their hosts: who’s been in contact with whom.
“The gut microbiome of red-bellied lemurs most closely resembles that of their group members. They are extremely cohesive and in contact a great deal, and rarely if ever interact with other groups, so this makes sense,” explains study co-author Assistant Professor Andrea Baden from Hunter college. “This explains a great deal of individual variation, but genetic kinship might explain some as well. We know that infants inherit a suite of microbes from their mother, during birth, for example. Since red-bellied lemurs leave their natal groups to form their own groups when they become adults, they might retain some bacteria from their natal family group. We can trace that by looking at kin relationships in the population, and similarity of the gut microbiome in kin.”
The study also includes some preliminary data around the relationship between social environment, social contact, bacterial transmission and hormonal changes, such as stress. The team are currently working to build on their initial observations, with new research understanding how an individual’s levels of the stress hormone cortisol are affected by their gut microbiome. “Social contact, stress physiology and gut microbiome are all intensely related. Your social contact defines how much stress you interact with, and both can influence the cocktail of microbes in your gut.”
Overall, this new research could also have implications for human health. “Just like lemurs, people find social situations, such as competition sometimes stressful,” said Ms Raulo. “However, primates also cope with stress through social means, by seeking and giving affection, grooming and touching each other, and so do people. This way, social contact also balances stress. Regardless of whether they are blood relatives, people that live in close quarters, also come to share similar gut bacteria. Synchronized physiological systems make us work more ‘as one’.”
In addition to the benefits of sharing the same microbiome, the authors are keen to understand how this knowledge can benefit human society, and potentially prevent the spread of autoimmune disease. “It is important to understand what builds up a healthy gut microbiome, and the role that the wider social and ecological environment plays in this,” said Ms Raulo. “Understanding that social environment and stress are directly linked to gut microbiome, could go some way to explaining why the western world experiences so many epidemics of autoimmune diseases, and help us to better treat people with them. Microbiome is the link between our internal physiology and the external ecosystem that together should tune us to understand our limits. When tackling modern epidemics of autoimmune disease, we cannot ignore the environmental problems our ecosystem is facing, nor the social problems our culture is facing.”
(2017) Social behaviour and gut microbiota in red-bellied lemurs (Eulemur rubriventer): In search of the role of immunity in the evolution of sociality. Journal of Animal Ecology. DOI: 10.1111/1365-2656.12781, , , Amato, K., Knight, R., Leigh, S., Stumpf, R., White, B., Nelson, K.E., Baden, A.L. and Tecot, S.R.