It used to be, a New Scientist editorial says, that bacteria were either good or bad. They either helped us digest our food or they made us sick.
Increasingly, though, bacteria seem to be able to do both. For instance, the New Scientist points out that Mycobacterium tuberculosis, which causes the disease tuberculosis, has also been implicated in allowing people to evolve large brains.
"This is just a theory," it adds, "but it is clear there is still a lot to learn about the interactions between us and our microbes."
Microbiome research, the New Scientist says, is taking off and has the potential to uncover other such benefits.