Gut Microbes Linked to Brain Size Evolution in Primate Study

New research has identified a connection between gut microbes and metabolic patterns related to brain size in primates, providing insight into how microbiota may influence host physiology.

The study, published in Microbial Genomics, involved transferring gut bacteria from humans, squirrel monkeys, and macaques into germ-free mice and observing changes in the animals' metabolism and physiology.

Researchers measured several physiological traits in the mice, including weight gain, body fat percentage, fasting glucose, and liver function, to assess how different primate microbiota affected their hosts.

Mice that received gut microbes from humans and squirrel monkeys, both species with larger brains, showed metabolic changes that favored increased energy production and usage. In contrast, mice given microbes from macaques, which have smaller brains, demonstrated greater fat storage.

What the numbers show

• The study was published on December 2, 2024
• Gut microbiota from three primate species were used: human, squirrel monkey, and macaque
• Physiological traits measured included weight gain, fat percentage, fasting glucose, and liver function

According to the publication, this research is the first to show that gut microbes from different animal species can directly cause metabolic differences associated with brain size across species.

Katherine Amato, associate professor of anthropology at Northwestern University and first author of the study, stated that differences in gut microbiota may represent an unexplored mechanism supporting the energetic needs of primate brains.

The findings indicate that gut microbes could have contributed to the evolution of larger brains by influencing energy metabolism in their hosts. This suggests a possible link between microbiota composition and brain development across primate species.

Researchers have announced plans to expand their investigation by including additional primate species with a range of brain sizes and by examining other factors such as microbial compounds, immune function, and behavior.

* This article is based on publicly available information at the time of writing.