https://www.selleckchem.com/products/s-glutamic-acid.html Since the time of Darwin, evolutionary biology has recognized that groups are the key to the evolution of cooperation. With many small groups, chance associations of cooperators can arise, even if cooperation is selected against at the individual level. Groups of cooperators can then outcompete groups of defectors, which do not cooperate. Indeed, numerous symbioses may have arisen in this way, perhaps most notably the symbioses of host cells and chemiosmotic bacteria that gave rise to the eukaryotic cell. Other examples in which one partner relies on chemiosmotic products supplied by the other include lichens, corals or other metazoans and dinoflagellates, sap-feeding insects, and plant-rhizobia and plant-mycorrhiza interactions. More problematic are cases of gut microbiomes-for instance, those of termites, ruminants, and even human beings. Under some but not all circumstances, chemiosmosis can be co-opted into punishing defectors and enforcing cooperation, thus leading to mutualistic symbioses.Symbiogenesis presents the biologist with very different explanatory issues compared to the lineal and selectionist view of evolution based on individual entities, whether genes, organisms or species. A key question is how the co-existence of two or more partners in close association during a given generation can ultimately be stabilized enough to be transmitted to the next, how the ensuing complexity is maintained and how this arrangement impacts the reproductive fitness of the collective over evolutionary time. In this chapter, we highlight some observations gleaned from the microbial world that could shed light on this problem if viewed within the framework of constructive neutral evolution.Many complex diseases are expressed with high incidence only in certain populations. Genealogy studies determine that these diseases are inherited with a high probability. However, genetic studies have been unable to identify the