Years ago, I read [b:Life On Man|9347542|Life On Man|Theodor Rosebury|https://images.gr-assets.com/books/1437958401s/9347542.jpg|3805548] by [a:Theodor Rosebury|1602817|Theodor Rosebury|https://s.gr-assets.com/assets/nophoto/user/u_50x66-632230dc9882b4352d753eedf9396530.png]. (and also his [b:Microbes and Morals|3971855|Microbes and Morals|Theodor Rosebury|https://s.gr-assets.com/assets/nophoto/book/50x75-a91bf249278a81aabab721ef782c4a74.png|4017612]) yet I remember little about them. I remember liking them (why I read two of them). I bring them up because Mr Roseburry is frequently quoted in I Contain Multitudes, a book that is in a very real sense it's predecessor. Interestingly, Rosebury was a scientist and researcher while Ed Yong is a journalist yet Rosebury is the better writer of the two (if I recall my reading experience correctly). I say this because at times Mr. Yong gives too much detail for a lay reader such as myself and I found it hard to follow what I probably didn't need to follow at all.

There is so much I learned from this book. Multitudes, perhaps. Much has been discovered since Rosebury's day thanks to advances in genetics technology, primarily gene sequencing and genomics. (The one review I read of Microbes and Morals on Goodreads declared it as "dated" though my guess is that the reviewer was talking more about changes in morals than in our knowledge of microbes)

Still, the most surprising thing about this book is how it changes our view of who we are in the same way Roseburry's did (which didn't last and I needed it to be done again.) Only about 50% of our cells are "human," the remainder belonging to various colonies of microbial life without which we wouldn't be able to survive. For example, they are part of our immune system and our digestive tract. They evolved along side us in cooperation with us (preceding us for millions of years) and yet we tend to think of them as enemies, characterizing them by the tiny percentage of them which cause disease. Even as I sit here typing on a computer keyboard that is swarming with them, there are millions more microbes hanging out on my face and hands, living in the forest of my hair and the tropic beach of my mouth crossing the unpatrolled borders of my lips like undocumented aliens when I breathe in and out. We continually exchange our microbes with strangers, on light switches and doorknobs, and with intimates more directly in other ways.

One of the reasons people become ill in hospitals is not merely because of the proximity to sick people but because the internal environment is over-cleaned removing those microbes that protect us. The same antibiotics that kill the germs that make us ill also make us more vulnerable to an influx of different pathogens from which we previously had been protected. In fact, those toilet seats that are sanitized for our protection soon after have more bacteria than before they were cleaned because they lack the "good" microbes that had been killed of in the sanitizing process. Florence Nightingale, Yong tells us, would open windows in hospitals because she noticed that the health of patients near them would improve. We now know that this is because it allows external bacteria into the oversanitzed environment.

Along with this change in how I view myself (and my cats) I learned about the kinds of research being done, e.g. the effects of gut bacteria on anxiety and depression, the project to eliminate dengue fever, studies investigating the relationship of our microbial partners to hypertension and obesity, how the rise in autoimmune diseases my be related to the eradication of many childhood diseases.

I recently tried to discuss some of these ideas with a germaphobe of my acquaintance but he found what I was saying toxic and refused to listen. Don't be like him. Read this book.