the human body as ecosystem

When invaders to manage to get in, our ecosystem changes. Experiments have shown that when pathogens invade a mouse’s gut, the diversity of its residents drops. The effect is akin to what happened when [fish called] alewives recolonized Connecticut lakes: they sent shock waves through the food webs. Another shock to our inner ecology comes from antibiotics. Antibiotics not only wipe out the pathogens that make us sick, but a lot of the ones that make us healthy. When antibiotics work, only the beneficial bacteria grow back. But the body’s ecosystem is different when it recovers, and it can remain different for months, or even years.

In the September 2010 issue of the journal Microbiology and Molecular Biology Reviews, a team of researchers looked over this sort of research and issued a call to doctors to rethink how they treat their patients. One of the section titles sums up their manifesto: “War No More: Human Medicine in the Age of Ecology.” The authors urge doctors to think like ecologists, and to treat their patients like ecosystems. ….

[O]bese mice have a different microbial ecosystem than regular mice. And if you take the stool from one of these obese mice and transplant it into a mouse that has been raised germ-free, the recipient mouse will gain more weight than recipients of normal gut microbes. The microbes themselves are altering how obese mice are processing energy.

Obesity is just one medical disorder among many that the microbiome can influence. It’s also been linked inflammatory bowel disease, obesity [sic], colon cancer, hypertension, asthma, and vascular disease. If we can manipulate our inner ecosystem, we may be able to treat some of these diseases.

Carl Zimmer, “The Human Lake“, Loom (Discover blogs), 31 March 2011.

Science writer Carl Zimmer (b. 1966) is author of numerous books, including Microcosm: E. coli and the New Science of Life (Pantheon, 2008). In this blog entry, he takes us on a long journey from G. Evelyn Hutchinson (1903-1991), regarded as the father of modern ecology, to biophysicist Max Delbrück (1906-1981), who received a Nobel Prize in 1969, then on to the recent work of University of Minnesota gastroenterologist Dr Alexander Khoruts.

This is a fascinating story, richly illustrated, that all will enjoy.

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