The primate gut microbiota contributes to interspecific differences in host metabolism

Area of Science:

• Comparative physiology
• Microbiome research
• Evolutionary biology

Background:

• Large brains require significant energy, necessitating specific metabolic adaptations in vertebrates.
• The precise biological mechanisms driving these metabolic differences across species remain largely unknown.
• The gut microbiome's role in host metabolism is established in disease contexts, but its influence on normal metabolic variation is less understood.

Purpose of the Study:

• To investigate the hypothesis that the gut microbiome contributes to species-specific metabolic differences, particularly those linked to brain size.
• To explore the gut microbiome's potential role in the energetic demands of large brains and its implications for vertebrate evolution.

Main Methods:

• Germ-free mice were colonized with gut microbiota from three distinct primate species with varying relative brain sizes.
• Metabolic changes in the host mice were analyzed following colonization.

Main Results:

• Gut microbiota from larger-brained primates induced a host metabolic shift towards increased energy expenditure and production.
• Gut microbiota from smaller-brained primates promoted energy storage in adipose tissues.
• These findings demonstrate a causal link between primate gut microbiota composition and host metabolic phenotypes related to brain size.

Conclusions:

• The gut microbiome plays a causal role in interspecific metabolic variation associated with relative brain size.
• The gut microbiome may have been a critical factor in facilitating the metabolic adaptations required for encephalization during human evolution.