Microbiology of the Anthropocene

Human influences on the planet's atmosphere, hydrosphere and biosphere are of such magnitude as to justify naming a new geological epoch, the Anthropocene. Different starting dates and phases have been proposed for this epoch, depending on the criteria used. Recent advances in microbial genomics and ecology show that human perturbations to microbial populations correspond closely to the proposed phases of the Anthropocene: the 'paleoanthropocene' which began with the rise of agriculture; the industrial revolution, from the late 1700s; and the 'Great Acceleration' from the 1950s to the present day. As the Anthropocene unfolds, environmental instability will trigger episodes of directional natural selection in microbial populations, adding to contemporary effects that already include changes to the human microbiome; intense selection for antimicrobial resistance; alterations to microbial carbon and nitrogen cycles; accelerated dispersal of microorganisms and disease agents; and selection for altered pH and temperature tolerance. Microbial evolution is currently keeping pace with the environmental changes wrought by humanity. It remains to be seen whether organisms with longer generation times, smaller populations and larger sizes can do the same.