Social bonds steer wild horses' gut microbes, outpacing bloodlines

On Sable Island off Nova Scotia, feral horses from the same herd share more similar gut microbiomes than would be expected by genetics alone, and social interactions appear to shape these microbial communities even more than kinship, with microbiome differences linked to survival; the study suggests microbiome-mediated adaptive evolution in a wild population, though it remains preliminary and focused on one island.