 Most recently, a new topic has arisen in the context of multilevel selection, involving the evolution of “holobionts,” i.e., the combination of a eukaryotic organism with its microbiotic load (Zilber-Rosenberg &amp; Rosenberg 2008). It has become clear that each “individual” human being is actually a community of organisms co-evolved for mutual benefit (Gilbert, Sapp, &amp; Tauber 2012). Our microbiota (the collection of bacteria, viruses, and fungi living in our gut, mouth, and skin) is necessary for our survival and development, and our species is also needed in turn for their survival. Bacterial symbionts help induce and sustain the human immune system, T-cells, and B-cells (Lee &amp; Mazamanian 2010; Round, O’Connell, &amp; Mazamanian 2010), as well as providing essential vitamins to the host human being. Gut bacteria are necessary for cognitive development (Sampson &amp; Mazamanian 2015), as well as for the development of blood vessels in the gut; lipid metabolism, detoxification of dangerous bacteria, viruses, and fungi; and the regulation of colonic pH and intestinal permeability (Nicholson et al. 2012).