https://www.sciencemag.org/news/2021...ain-aging-mice
Arya Biragyn, a molecular biologist at the National Institute on Aging, says he would have liked the team to have done more to show the microbiomes had actually changed in the older mice. Because the researchers checked for differences in the gut microbiome soon after the transplants, there’s no way to know whether the new microbes had truly moved in or were just passing through, he argues.