The Anthropocene names an antibiotic age: an era marked by systematic efforts to extinguish or control the diversity and complexity of the living world. Some of us have proved remarkably capable of such endeavors. Landscapes have been ordered, bodies purified, and many forms of difference subsumed to the anthropocentric logics of modernity.

Concerns are now brewing that such dreams of control and their simplified, stable worlds may be as pathological as worlds of excessive abundance. For example, anxieties about the loss of biological diversity and ecosystem function out there (Holling and Meffe 1996) resonate with worries about missing microbes and dysbiosis in here (Blaser 2014). Modern life is said to be plagued by “an epidemic of absence” (Velasquez-Manoff 2012). The loss of bodily microbes and shifting encounters with nonhumans large and small are being linked to spectacular rises in noncommunicative diseases of both mind and body. Allergies, autoimmunity, depression, and a host of other complaints are cast in terms of our disentanglement from the nonhuman worlds in and around us. Archetypal modern innovations like sanitation, urbanization, Caesarean sections, and bottle-feeding have been flagged as deleterious to our microbial selves (Blaser and Falkow 2009).

In response, alternative modes of managing life are emerging that I want to describe as probiotic. I use this term advisedly. Probiotic is much more than what you buy in a health food shop: an expensive foodstuff distinguished by the addition of a single strain of microbial life. What I have in mind is a more expansive set of interventions geared toward the systematic modulation of political ecologies conceived as dynamic milieu characterized by multiple stable states, intensive relations, and spatiotemporal rhythms punctuated by tipping points. Probiotic interventions target ecologies that have already tipped, seeking to revert, restore, or rewild them in the interests of improved functionality. They involve environmental modes of biopower (Foucault 2010), working with and against the various logics of biosecurity (Massumi 2009; Braun 2014).

Two sets of examples might suffice to illustrate this probiotic turn. The first comes from the management of life in those flagship sites for nature: national parks. A shift is underway in the priorities of some forms of wildlife conservation from species composition to ecological function, resilience, and adaptive capacity. A growing awareness of the novelty of the ecologies of the Anthropocene has coincided with a popular interest in rewilding. Rewilding comes in several guises (Lorimer et al. 2015), linked by a common interest in introducing so-called keystone species: organisms capable of reorganizing target landscapes by virtue of their disproportionate ecological agencies.

The most famous example is the wolves of Yellowstone. Their dwindling over the course of the twentieth century unleashed what is known as a trophic cascade on the park’s ecology, causing corollary effects on the grazing practices of Elk and other herbivores. But the deliberate reintroduction of the wolves in the 1990s was given credit for reversing these effects; wolves, here, engineer entire landscapes. Rewilding forms part of a wider rethinking of the management of ecological disturbances. Coastal and river managers speak of rewetting floodplains and working with natural processes, while forest managers consider naturalistic modes of fire management or biological forms of pest control.

A second set of probiotic interventions are underway in relations with human microbiomes. Long vilified as pathogenic, there is now a growing interest in the salutary potentials of some microbes. For example, immunologists draw attention to the vital role played by a range of microbes in training the human immune system. Martial metaphors of a body primed for the defense of an essential human self are giving way to more variegated understandings of bodily tolerance, experimentation, or even active recruitment of microbial organisms for the symbiotic maintenance of bodily functionality (Gilbert, Sapp, and Tauber 2012).

Formerly taboo parasites have come to the fore as potential biotherapy agents. Species like human hookworm have been revalorized for their keystone qualities, promoted—like the wolves of Yellowstone—for the ability to train and modulate human bodily ecologies prone to autoimmune and inflammatory disease. It seems that hookworm can communicate with our gut microbes, shaping internal ecologies to establish mutualistic relations (Bilbo et al. 2011). Several thousand people currently self-medicate with a range of hookworms and other helminths. There is a form of inner rewilding underway here.

Such biotherapies can be positioned alongside broader probiotic enthusiasms in late modern societies. For instance, there is a growing interest in the hygienic potential of bacterial mixtures for deodorizing and sanitizing both bodies and the built environment. Other interventions seek to replicate the bacterial colonization associated with vaginal birth for babies born by Caesarean section, or else provide safe fecal matter for transplants to inhibit antibiotic-resistant bacteria. The publishing world is awash with popular science and self-help books encouraging us to work on our microbiomes, in incarnations ranging from the neoprimitivist to the techno-optimist. Their efforts are assisted by the rise of personalized metagenomic sequencing companies. These allow consumers to map their inner ecologies and cross-reference this data with other metrics of their quantified selves.

These tendencies are heterogeneous, and it might be a little grandiose to talk of a single probiotic turn. They are also fissured by familiar and unequal political geographies and ecologies. For example, antibiotic programs to deworm the world persist in parts of the global South marked by poor sanitation and drug delivery, where absence is more desirable than excessive presence. Similarly, rewilding in temperate nature reserves and abandoned marginal agricultural landscapes must be viewed in the context of the globalization of agriculture and the persistent, antibiotic, and often violent intensification of land use in tropical areas.

Even so, might these diverse probiotic trends offer some directions for an Anthropocene yet unseen? As an environmental mode of biopolitics, being probiotic still involves making live and letting die. In the Anthropocene, such calculations are now necessarily performed at a global scale. But perhaps there are the makings here of new worlds attuned to living with feral relations (Tsing 2015). There are stories to be told across these fragments about future epochs to be made in common, within ecologies kept within safe and habitable limits.