Gut microbiota as a candidate for lifespan extension: an ecological/evolutionary perspective targeted on living organisms as metaorganisms.

An emerging central concept in evolutionary biology suggests that symbiosis is a universal characteristic of living organisms that can help in understanding complex traits and phenotypes. During evolution, an integrative circuitry fundamental for survival has been established between commensal gut microbiota and host. On the basis of recent knowledge in worms, flies, and humans, an important role of the gut microbiota in aging and longevity is emerging. The complex bacterial community that populates the gut and that represents an evolutionary adapted ecosystem correlated with nutrition appears to limit the accumulation of pathobionts and infections in all taxa, being able of affecting the efficiency of the host immune system and exerting systemic metabolic effects. There is an urgent need to disentangle the underpinning molecular mechanisms, which could shed light on the basic mechanisms of aging in an ecological perspective. Thus, it appears possible to extend healthy aging and lifespan by targeting the host as a metaorganism by manipulating the complex symbiotic ecosystem of gut microbiota, as well as other possible ecosystems of the body.