Why is showering bad for our skin bacteria? (evolutionary questions)

After reading Alanna Collen’s 2015 book 10% Human: how your body’s microbes hold the key to health and happiness, I have become interested in, among other topics featured in the book, the work of the AOBiome company. Collen mentions this company in the context of aspects of our modern lifestyle which may be detrimental to the beneficial microbes that live on and in us. In this particular case, it is the practice of showering every day with body soap and deodorant that may be disproportionately displacing certain types of bacteria that process ammonia and help control the bacteria responsible for giving us body odor. AOBiome proposes that by replenishing these ammonia-oxidizing bacteria (AOBs) on our skin, we can reduce or eliminate the need for deodorants and showers. We can also replenish them through contact with soil or untreated (an unpolluted) water, according to Collen. I have read up on AOBiome a bit, and their scientific logic seems sound and is backed up by pilot studies they have done (see end for links). However, I have some questions about the evolutionary biology side of things: Continue reading