Ecosystems go all the way up and all the way down. Just as humans affect -- and are affected -- by the bigger world of animals, forests, oceans, and sky, we are also part of a deeper micro-sized world of bacteria and viruses, many (most?) of them far older than we are, and constantly adapting to all the harshness of life, including the new realities of human-made antibiotics and hygiene. Control over nature is an old goal of science, but nature is never fooled forever. The great bridges and dams that make one side of our lives better can have unforeseen consequences to other parts of our world.
So it is with the micro world too. Even the simplest steps we take to keep clean or warm, conveniences like indoor plumbing or heating, induce changes to unseen world of microbes, which not only outnumber us but out-class us in diversity and complexity. Eliminate one from our lives and who knows what it will do.
Moises Velasquez-Manoff presents an intriguing and sometimes terrifying survey of what little is known about the microbes around us. Focusing on allergies and autoimmune diseases, he writes in detail about the "hygiene hypothesis", that as the world gets richer and cleaner, our under stimulated immune systems get bored and turn on the body itself. A whole range of new diseases, from hay fever to asthma to crohn's disease, all seem to co-occur with modernity. People of the same genetics and culture -- Finns separated by the Iron Curtain, for example -- suffer these diseases at very different rates. Even zoo animals develop afflictions unknown in the wild. The more "clean" and "modern" you are, the more you invite previously unheard of conditions.
Even more intriguing is the "old friends" hypothesis, that having co-evolved with us, many of these microbes are actually necessary for health. From digestion to mood, when you take away the organisms that have covered us for millions of years, you invite trouble. Sadly, by driving many of these creatures to extinction -- an inadvertent result of hygiene practices intended to wipe out other afflictions -- we may be adversely affecting our human ecosystem in ways we don't yet understand. Wipe out a wolf population to spare human livestock and the deer begin to trample wild plants, carving the forest in unpredictable directions. There is some good, of course, but some bad too, and the scary part is that science doesn't know way too little about which is which.
I am extremely fortunate to have been spared many of the awful afflictions presented in this book: hay fever, peanut allergies, asthma, eczema and more. So little is known about how to treat the sometimes terrible discomforts involved, and if you suffer from them, you may understandably be willing to try just about anything, including treatments with parasites like hookworm, so mainly you want to know: does it work? The answer is maybe, but not definitely, and you may also introduce other problems. The author recounts how he self-inflicted in a Tijuana clinic (sadly, the treatment is illegal in the US) and yes, it helped. But the side effects (headache, diarrhea) were no picnic, and the treatment is no cure: to maintain relief from allergies, he needs to continue taking the worms. With no independent auditors in place, you run the risk of acquiring other diseases along with the worms: HIV maybe or hepatitis -- the cure can be worse than the disease.
This definitely was one of the best science books I've read in a long time, and if you or a loved one suffers from autoimmune diseases, you'll appreciate the well-written and thorough survey of what is known. I doubt there is any work nearly as good; I think this is one of those areas of science that is so new, and so potentially different from centuries of medical progress, that you really need somebody like this author -- not a scientist, but a science journalist -- to look into the issues and present them for you (which he does, well, and with the right amount of both optimism and skepticism).
A sampling of some ideas: how pregnancy is central to the passing of important microbes. Yes, you should lick your baby's pacifier, and chew their food for them if you can -- the microbes in your saliva are highly optimized for your genes and environment. Even autism may have a microbe component: some kids reverse their symptoms when fighting a fever, or an infection. H. pylori, the strange bug whose role in ulcers earned its discoverers a Nobel prize, may actually be necessary in many of us.
In fact, the lesson of h. pylori or the EVB virus is a good summary of many of the bugs around us: often they are neither all good nor all bad. Nature is not a fight between pure good and pure evil, but rather a constant tension among multiple constituencies vying for power. Rather than focus on permanently vanquishing one or another "foe", we need to consider the entire ecosystem and realize how little we really know after all.
