Across the span of a human life, the invisible ecosystem within us may quietly shape the fate of our minds — a possibility that modern science is only beginning to trace with precision. A new review in Frontiers in Molecular Neuroscience draws together a growing body of evidence suggesting that the gut microbiota, sculpted by what we eat, communicates with the brain through immune, metabolic, and neural channels in ways that may influence cognitive aging. The pathways are increasingly legible, the biological logic is compelling, and yet the honest conclusion is that most of what we know was le