- • Scientists transferred gut microbes from different primates into germ free mice and the mice showed brain activity patterns that resembled the donor species.
- Microbes from larger brained primates were linked to higher activity in genes involved in energy production and learning related pathways, while microbes from smaller brained primates produced different patterns.
- The research strengthens the gut brain connection but it is not evidence that probiotics can treat mental health or boost intelligence.
Humans have unusually large brains for our body size and brains demand a lot of energy.
Researchers have long debated what helped fuel this evolutionary jump.
A new study suggests gut microbes may be part of the story, by shaping energy supply and brain development pathways.
In the experiment, scientists took gut microbes from primates with different relative brain sizes and introduced them into mice raised without any microbes of their own.
They used microbes from humans and squirrel monkeys as examples of larger brained primates and from macaques as an example of a smaller brained primate.
After eight weeks, the mice showed clear differences in brain gene activity depending on which microbes they received.
Mice given microbes from the larger brained primates had higher activity in genes linked to energy production and synaptic plasticity, which supports learning and adaptation.
Mice given microbes from the smaller brained primate showed different patterns and the researchers reported overlaps with gene expression signatures that have been associated in other research with conditions such as ADHD, schizophrenia, bipolar disorder and autism.
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The most important point is what this does and does not show.
It supports a causal role for the gut microbiome in shaping aspects of brain function during development in an animal model.
It does not show that changing your microbiome will improve cognition or treat mental health conditions in humans.
For people living with diabetes, the gut microbiome is already a major area of interest because of its links with metabolism, inflammation and insulin sensitivity.
Studies like this underline how interconnected these systems are, but the practical advice remains grounded: prioritise a varied, fibre rich diet, regular activity, good sleep and evidence based medical care rather than unproven microbiome shortcuts.
