Microbiome‑driven brain evolution

Transplanting gut microbes from primates with very different brain sizes into germ‑free mice produced brain gene‑expression patterns in the mice that resembled those of the donor species within weeks, including changes in energy and synaptic‑plasticity pathways and signals tied to neuropsychiatric risk. If reproducible, this suggests host‑associated microbes could be a causal axis in the evolution of brain energetics, cognitive capacity, and disorder vulnerability. — This reframes questions about the origins of human cognitive differences and psychiatric risk toward ecology (microbiomes) as well as genetics, implying new research funding priorities, clinical screening concerns, and ethical debates about microbiome engineering.