Here is a potentially disturbing thought for some of you: there are more bacterial cells in and on your body than there are cells for your body. Of course this is not a fact to be overly concerned about as these bacteria are there for a myriad of reasons, such as enabling us to digest certain foods. Some foods our body cannot naturally digest, so there are bacteria colonies within our guts to convert that food into something we can digest. Now researchers at the University of Oklahoma are looking into how these bacteria have changed over time, due to changes in our diet, medicine, and habits.
To perform this study the researchers collected DNA from multiple sources including thousand-year-old fecal samples and frozen human bodies, including Otzi the Iceman. The researchers also collected data from non-western communities with a more traditional lifestyle than what you will find in the US. The results have thus far shown that even in just the past 100 years, our gut bacteria have changed greatly, especially in cosmopolitan areas. This is likely due to our habits to sanitize our world and kill any microbe that could make us sick.
Of course destroying bad bacteria is not a bad idea but it is possible this behavior is causing some very unwanted side effects. Studies suggest there has been a recent increase in autoimmune risks, such as allegories, and others which may be linked to the disruption of good bacteria. If this link does exist then it may be by studying the human microbiomes of the past that these risks can be minimized.