What did the lost microbes do? If they helped digest things that aren't part of our diet then the there would be no selective pressure maintaining them, so they could be easily dropped, independent of the issues of vast over-application of antibiotics, etc.
Over application of antibiotics and anti-bacterial stuff is clearly causing problems, but that's not the only thing that is happening that impacts something as complex as the gut. Just as with genes, the microbiome is under constant selective pressure from evolution, and we will - over time - gain new microbes as we lose ones that aren't beneficial.
Over application of antibiotics and anti-bacterial stuff is clearly causing problems, but that's not the only thing that is happening that impacts something as complex as the gut. Just as with genes, the microbiome is under constant selective pressure from evolution, and we will - over time - gain new microbes as we lose ones that aren't beneficial.