The hidden fuel of the human brain: How gut bacteria shape intelligence?

Bacteria that aid in producing more metabolic energy may have been key to the evolution of large brains.

The evolution of large brains , a hallmark of humans and some other primates, has long fascinated scientists. While many theories have been proposed, a new study from Northwestern University offers a completely new perspective on the role of gut bacteria in this process. The finding not only opens up new insights into evolutionary biology, but also underscores the importance of the microbiome in brain development.

Researchers have found that gut bacteria from large-brained primates such as humans and squirrel monkeys can promote energy production, suggesting a role for microbes in the evolutionary development of large brains.

Brain tissue is considered one of the most energy-consuming organs in the body.

Secrets hidden in gut bacteria

Brain tissue is considered one of the most energy-consuming organs in the body. Therefore, large-brained animals such as humans require a lot of energy to support both brain development and maintenance. However, how our ancestors met this huge energy demand during the evolutionary process remains a question that has not been satisfactorily answered.

Research published in the journal Microbial Genomics on December 2 has shown that gut bacteria play a key role in meeting the brain's energy requirements. Scientists found that bacteria from large-brained primates not only influence how the body processes energy, but also regulate energy use in the brain.

Breakthrough Experiment: Bacteria from Humans to Mice

To test the hypothesis of the role of gut bacteria in the evolution of large brains, the team conducted a unique experiment. They transplanted bacteria from three different primate species into mice: humans, squirrel monkeys (a large-brained primate), and common baboons (a smaller-brained primate).

The results showed that mice with bacteria from humans and squirrel monkeys consumed more food, grew more slowly, and accumulated less body fat. Instead of storing energy as fat, these mice used excess energy to produce glucose, the main fuel source for the brain. Meanwhile, mice with bacteria from normal monkeys tended to store more energy as fat.

New research suggests that the gut microbiome may influence the energy available to develop a larger brain.

Gut bacteria: Companions of a big brain

According to Katherine Amato, associate professor of anthropology at Northwestern University and lead author of the study, the bacterial community that lives in the large intestine has the ability to produce compounds that have powerful effects on the host's biology.

'We know that gut bacteria can regulate metabolism and influence aspects like insulin resistance and weight gain. This new finding suggests they also play an important role in fueling the brain,' Amato explains.

Notably, the mice that received bacteria from humans and squirrel monkeys showed similar biological traits, even though the two primates are not closely related. This suggests that the independent evolution of large brains in both species led to similar changes in gut bacterial communities, in response to increased energy demands.

Impact on understanding of evolution

This finding is the first evidence that gut bacteria not only aid in digestion but can also influence evolution by regulating how the body uses energy. This provides a new perspective on how internal factors and the symbiotic relationship between the host and gut bacteria can drive biological evolution.

Gut bacteria not only aid digestion, but may also influence evolution.

The research also lays the groundwork for other important questions: Did gut bacteria play a similar role in the evolution of other large-brained animals? And if so, can these insights be harnessed to improve human health?

To better understand the role of gut bacteria, the team plans to conduct experiments with different primate species. They also hope to gather more information about the compounds the bacteria produce, as well as their impact on host behavior and immune function.

'We believe that the microbial community is an important factor in explaining how primates, including humans, adapted to increasing brain energy demands during evolution,' Amato shared.

Research on gut bacteria and the evolution of large brains not only provides answers to fundamental questions in evolutionary biology but also opens up possibilities for applications in medicine and nutrition.

If we can understand and manipulate the gut bacterial community, we may find ways to improve brain health, control metabolic diseases, and even optimize cognitive abilities.

The journey into understanding the complexity of gut bacteria is just beginning, but early findings show great potential for improving the quality of life and expanding our understanding of the amazing evolution of humanity.