Bacteria that support higher metabolic energy production may be the key to the evolution of large brains.
The evolution of large brains, a prominent feature of humans and some other primate species, has long attracted the attention of scientists. While many theories have been proposed, a recent study from Northwestern University has provided a completely new perspective on the role of gut bacteria in this process. This discovery not only opens up new understandings of evolutionary biology but also underscores the importance of the microbiome in brain development.
Researchers found that gut bacteria from large-brained primates like humans and squirrel monkeys can enhance energy production, indicating the role of microorganisms in the evolutionary development of large brains.
The brain is considered one of the most energy-consuming organs in the body.
The Secrets Hidden in Gut Bacteria
The brain is considered one of the most energy-consuming organs in the body. Therefore, animals with large brains, such as humans, require a significant amount of energy to support both the development and maintenance of the brain. However, how human ancestors met this immense energy demand during evolution remains an unanswered question.
The study published in the journal Microbial Genomics on December 2 showed that gut bacteria play a crucial role in meeting the energy requirements of the brain. Scientists discovered that bacteria from large-brained primates not only affect how the body processes energy but also regulate energy usage for the brain.
Breakthrough Experiment: Bacteria from Humans to Mice
To test the hypothesis about the role of gut bacteria in the evolution of large brains, the research team conducted a unique experiment. They transplanted bacteria from three different primate species into mice: humans, squirrel monkeys (a species with a large brain), and macaques (a species with a smaller brain).
The results showed that mice transplanted 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 primary fuel for the brain. In contrast, mice transplanted with bacteria from macaques tended to store more energy as fat.
New research indicates that the gut microbiome may have influenced the energy available for developing a larger brain.
Gut Bacteria: The Allies of Large Brains
According to Katherine Amato, an assistant professor of anthropology at Northwestern University and the lead author of the study, the community of bacteria living in the large intestine can produce compounds that significantly affect the biology of the host.
“We know that gut bacteria can regulate metabolism and influence aspects such as insulin resistance or weight gain. This new finding shows they also play an important role in providing energy for the brain,” Amato explained.
A notable point in the study is that the mice transplanted with bacteria from humans and squirrel monkeys exhibited similar biological traits, even though these two primate species are not closely related evolutionarily. This suggests that the independent evolution of large brains in both species has led to similar changes in the gut microbiome to meet increased energy demands.
Implications for Understanding Evolution
This finding is the first evidence that gut bacteria not only support digestion but may also influence evolution by regulating how the body uses energy. This offers a fresh perspective on how internal body factors and the symbiotic relationship between hosts and gut bacteria can promote biological development.
Gut bacteria not only support digestion but may also influence evolution.
The study also lays the groundwork for other important questions: Do gut bacteria play a similar role in the evolution of other large-brained animals? And if so, can these insights be leveraged to improve human health?
To better understand the role of gut bacteria, the research team intends to conduct experiments with various primate species. They also hope to gather more information about the compounds produced by bacteria, as well as their effects on host behavior and immune function.
“We believe that the microbiome is a critical factor in explaining how primates, including humans, have adapted to the increasing energy demands of the brain during evolution,” Amato shared.
Research on gut bacteria and the evolution of large brains not only provides answers to fundamental questions about evolutionary biology but also opens up possibilities for applications in medicine and nutrition.
If we can understand and manipulate the gut microbiome, humans may find ways to improve brain health, manage metabolic-related diseases, and even optimize cognitive abilities.
The journey to understand the complexities of gut bacteria has just begun, but initial findings show great potential for improving quality of life and expanding our understanding of the remarkable evolution of humanity.
