The diversity of the gut microbiome impacts the health and nutrition of humans and (some) animals. While diet exerts the strongest influence on microbiome diversity, ecological factors like industrialization (for humans) and domestication (for animals) play a role, too.

Domestication can cause differences in mammalian gut microbial signatures, and this has been surveyed in a few mammals in independent studies. However, a recent study attempted to examine these differences across nine wild versus domesticated pairs of mammals, using pets, livestock, and laboratory animals. 

The researchers collected fecal samples of wild and domesticated mammals to extract the genetic information about their gut microbial communities. Though they did not see a single hallmark of domestication, they observed a common shift in the microbial composition of all domesticated animals. When they exchanged the diets of wild-caught and lab mice, they found that the dietary swap could only partially erase the microbiome differences between the groups. 

But the researchers were curious to know if the microbiota of lab mice could be artificially "re-wilded." So, they transplanted lab mice with poop from wild mice and also kept them on a wild diet. They saw that just this one fecal transplantation successfully shifted the microbiota of lab mice toward the wild donor profile, even without much help from the wild diet. 

The researchers also tested the swap diet on wolves versus dogs. Interestingly, while wolves gained microbial diversity on dog food, dogs lost diversity when fed with carcasses. Finally, the researchers compared wild chimpanzees to humans to draw parallels between domestication and industrialization. The profile of non-industrialized humans was more similar to chimpanzees than that of their industrialized counterparts, who were, in fact, similar to their pets.

Domestication has, therefore, left significant effects on the microbial gut community across multiple species of mammals. Examining these differences is essential to understanding host-microbiome-environment relationships, especially in the context of zoonotic diseases and antibiotic-resistant bacteria being harbored in domesticated animals.