It turns out that we are only 10 percent human: for every human cell that is intrinsic to our body, there are about 10 resident microbes — including commensals (generally harmless freeloaders) and mutualists (favor traders) and, in only a tiny number of cases, pathogens. To the extent that we are bearers of genetic information, more than 99 percent of it is microbial. And it appears increasingly likely that this “second genome,” as it is sometimes called, exerts an influence on our health as great and possibly even greater than the genes we inherit from our parents. But while your inherited genes are more or less fixed, it may be possible to reshape, even cultivate, your second genome.
Such a paradigm shift comes not a moment too soon, because as a civilization, we’ve just spent the better part of a century doing our unwitting best to wreck the human-associated microbiota with a multifronted war on bacteria and a diet notably detrimental to its well-being. Researchers now speak of an impoverished “Westernized microbiome” and ask whether the time has come to embark on a project of “restoration ecology” — not in the rain forest or on the prairie but right here at home, in the human gut.”
Bruce Sterling call the human gut the great unexplored rain forest of the 21C.
This would definitely caution against subsisting purely on Soylent… at least until you can start synth-bio’ing up hacks to your microbiota.