MICROBIOME NEWS: ‘Young poo’ makes aged fish live longer: The gut microbes of young killifish can extend the lifespans of older fish – hinting at the microbiome’s role in ageing. “Previous studies have hinted at a link between the microbiome and ageing in a range of animals. As they age, humans and mice tend to lose some of the diversity in their microbiomes, developing a more uniform community of gut microbes, with once-rare and pathogenic species rising to dominance in older individuals. The same pattern holds true in killifish, whose gut microbiomes at a young age are nearly as diverse as those of mice and humans, says Valenzano. ‘You can really tell whether a fish is young or old based on its gut microbiota.’ . . . The young microbiome ‘transplant’ also had dramatic effects on the longevity of fish that got them: their median lifespans were 41% longer than fish exposed to microbes from middle-aged animals, and 37% longer than fish that received no treatment (antibiotics alone also lengthened lifespan, but to a lesser extent).”