A recent study by Andrew Moeller and colleagues has revealed that social interactions can raise microbial diversity in the gut microbiome across chimpanzee generations. The study monitored the effect of chimpanzee sociability on gut microbiome diversity over an eight-year period. Faecal samples were collected and sequenced from 40 Kasakela chimpanzees in Gombe, Tanzania, at different stages of life. In addition, social behaviour and dietary composition were also collected across the study period.
Chimpanzees showed consistent seasonal variation in social activity, which was significantly higher during wet seasons (November through April) than during dry seasons (May through October). Gut microbial communities of socially interacting chimpanzees changed both within and between host generations. Interestingly, the inheritance of gut microbial communities across generations was primarily horizontal through social rather than vertical (parent to offspring) transmission. This observation highlights the importance of frequent social interaction in the development of beneficial microbial associations and their preservation over subsequent generations.
On the whole, social behaviour shaped the chimpanzee gut pan-microbiome, with a proliferation of the Olsenella phylotype over time. However, the degree of sociability among the chimpanzees during the sampling season did not affect the relative abundance or presence/absence of any specific bacterial groups. Although there was a lack of differentiation between wet- and dry-season gut microbial communities, chimpanzee gut microbiomes were more compositionally homogeneous during seasons in which hosts were more sociable. A high degree of sociability may therefore contribute to a major exchange of microorganisms among hosts, say researchers. These exchanges can occur either through direct contact between interacting hosts or indirectly through faeces deposited in the environment. Furthermore, species richness was promoted by both a combination of sociability and a uniform diet consisting of fruit, leaves and insects. Both in animals and humans, a high level of species richness in the gut microbiome may play a crucial role in maintaining health.
In conclusion, social behaviour may play an essential role in the preservation of gut microbial diversity across host generations. The researchers suggest their results should be explored in human societies, with a focus on its impact on future generations.
Moeller AH, Foerster S, Wilson ML, Pusey AE, Hahn BH, Ochman H. Social behavior shapes the chimpanzee pan-microbiome. Sci Adv. 2016;2(1):e1500997.