The science and philosophy writer Dorion Sagan, son of Lynn Margulis, began his 2011 lecture in the Anthropological Society’s series The Human is More than Human by quoting from Claire Folsome’s entry for ‘Microbes’ in the 1985 book The Biosphere Catalogue. Folsome describes a thought experiment in which an alien drops down through the ceiling and points a gun at you. The gun is trained to ‘annihilate every human cell in your body’. According to Folsome, after the alien shoots it at you,
What would remain would be a ghostly image, the skin outlined by a shimmer of bacteria, fungi, roundworms, pinworms and various other microbial inhabitants. The gut would appear as a densely packed tube of anaerobic and aerobic bacteria, yeasts, and other microorganisms. Could one look in more detail, viruses of hundreds of kinds would be apparent throughout all tissues.
Folsome’s imagery is provocative, highlighting that each one of us, apparently singular and self-contained, is an ecology of untold depth unfolding at multiple scales and temporalities. The thought experiment relies on the very distinction that it calls into question, that is, the distinction between ‘self’ and ‘other’. The new microbiology shows us that the nonhuman matter that remains once all human cells have been eliminated is not a residue of contingent parasites, but microorganisms absolutely integral to our being and becoming, organisms without which ‘we’ could not even extract energy from food. In fact, our relation to microbes is, as Myra Hird argues, radically asymmetrical: ‘microbial life invented the basic metabolic processes, including photosynthesis and chemical conversion, that every other life form remains utterly dependent on’. It is this new microbiology that contributes to a decentering of the human in a development that is postanthropocentric, posthumanist and post-dualist.
As a bounded, continuous and materially identifiable entity, the figure of the human cast under the light of the new microbiology is ruptured. In this loss of self identity, however, the human becomes more strongly integrated into an ecological understanding. Firstly, the human body itself is considered as an ecology of many species, a temporarily discrete node of activity, materialised around and rooted significantly in microbial presence and metabolism. Secondly, the human body is figured as necessarily acting and being acted upon within the context of an open ecosystem, linked by chains of connection to microbial life-worlds beyond its own skin and extending into every environment.
What seems to come ‘after’ the human then, in light of this new microbiology, is the recognition that, as Scott F. Gilbert claims, ‘we have never been individuals’. We become posthuman in the recognition of our entwinement with, and responsibility to, nonhuman actors. Following Peter Sloterdijk, Bruno Latour suggests that history was never about modernisation and emancipation from our connections to the nonhuman material world, but about the ‘explicitation’ of these very connections:
As we moved on, through our technologies, through our scientific inquiries […] we rendered more and more explicit the fragility of the life support systems that make our ‘spheres of existence’ possible. Everything that earlier was merely ‘given’ becomes ‘explicit’. Air, water, land, all of those were present before in the background: now they are explicitated because we slowly come to realize that they might disappear —and we with them.
Latour collapses the distinction between scientific knowledge of the world and the effects of our actions upon that world. Thus, as we learn more about our connection to microbes, it is increasingly in the context of their waning diversity, of dysbiosis, of their necessity in human health, and antimicrobial resistance, contexts in which humans as actors are deeply implicated.
The notion of history as a linear development towards the liberation of humanity from the constraints of the natural world, therefore, can only be maintained insofar as the unintended effects of these ‘liberations’ lag behind their immediately intended effects. In the case of antimicrobial resistance, the temporal split between these effects — the gap in which the illusion of emancipation can be sustained — is as thin as a hair, thereby thrusting us into an acknowledgement of our worldly entanglement. As Hannah Landecker recounts, ‘penicillin was first given to patients in 1941. Penicillin resistant bacteria were detected in 1942. And so it goes: Methicillin introduced 1960. Methicillin resistance reported in 1961’. Indeed, it was precisely attempts to make microbes (specifically, pathogenic microbes) ‘disappear’ with drugs targeted to their metabolism that hastened their evolution, redoubling humanity in a crisis of its own making.
In this story, microbes appear less as an element that deconstructs the figure of a self-bounded and autonomous human agent, and more as a form of resistance to assumptions of the centrality of human agency in control of a predictable and pliable material world. Here too, explicitation is given another, somewhat inverted, dimension. This is not about humanity’s dependence on certain biotic and abiotic conditions, and how the degradation of these conditions implicates our own disappearance; it is about how the attempt to eradicate those factors which are already causing the disappearance of (some) humans in the present will not necessarily ensure our survival in the future, but may actually throw it into greater doubt and uncertainty. The dynamics of antimicrobial resistance call into question the boundary between ‘health’ and ‘disease’ and the scale(s) at which this boundary operates.
The ‘failures’ of antibiotic use (or rather, the paradigms in which they are mobilised en masse) reveal fundamental features of the co-evolution of humanity’s technological capacity and its microbiological counterparts. Because microbial life-worlds are emergent, and humanity depends upon bacteria as much as it is halted by them, ‘we’ cannot get rid of ‘them’. To do so is neither possible, nor desirable. Paradoxically, it is the micrological mechanisms catalysing the processes of antimicrobial resistance, namely transduction and recombination of DNA, that are technologised in some of the more recent attempts to extract humanity from biological limitations: genetic engineering. Peter Mahon discusses the posthuman implications of humanity’s ‘discovery’ of genetic engineering:
The fact that human genetic engineers have learned to perform ‘sex’ [genetic transduction and recombination] like ancient bacteria underscores how genetic manipulation is posthumanist insofar as it repeatedly puts into question any notion of a hard and fast boundary between human and nonhuman.
He goes on to elaborate this question, stating how the ‘processes and mechanisms of genetic manipulation cannot be considered as simply human tools since they were originated by viruses and bacteria’. Moreover, because ‘genetic engineering can splice together the genetic material of different species […] it has the power to splice human genes with nonhuman genes to create genetically enhanced or designer posthumans’. It is this power and its associated ethico-political ambiguities that renders the microbial, as Stefan Herbrechter notes, ‘a true ‘Pharmakon’ […] representing both poison and remedy’.
Ultimately, the figure of the microbe embodies a tension between critical posthumanist discourses that embed humanity in the material world, rendering it accountable to that world, and a transhuman posthumanist discourse that valorises the overcoming of humanity’s biological limitations, emancipating it from that very material world. Although microbes and bacterial lifeforms, and their repertoires of genetic ‘tools’, are increasingly upheld as exemplars of the precision of human agency, the potential of the microbial resides in its ability to continually disrupt these notions and thereby provide new articulations for a posthuman future.
– University College London, June 2020
 Lynn Margulis was an evolutionary biologist instrumental in reconfiguring notions on the evolution of complex life, and consequently the position of humanity in relation to nonhuman organisms, especially microbial organisms. She argued that symbiosis is the driver of evolution and offered a theory of symbiogenesis, in which microbes are at the beginning of all life. For example, endosymbiosis, developed by Margulis in the 1960s and not adopted in mainstream biological canon until the 1980s, is the proposition that the energy-producing mitochondria found in all of our bodies’ cells were once free-living microbes that fused with other cells, entering a symbiotic relationship. In fact, in Margulis’ view, ‘it is not preposterous to postulate that [our] very consciousness…may have been born of the concerted capacity of millions of microbes that evolved symbiotically to become the human brain’ (Sagan and Margulis, Microcosms, Four Billion Years of Microbial Evolution (Berkeley: University of California Press, 1986) p. 34).
 Dorion Sagan, ‘The Human is More than Human: Interspecies Communities and the New “Facts of Life”’ (2011); available on the Fieldsights site at: https://culanth.org/fieldsights/the-human-is-more-than-human-interspecies-communities-and-the-new-facts-of-life (accessed 21/06/2020).
 Clair Folsome, ‘Microbes’, in The Biosphere Catalogue, ed. by T. P. Snyder (Fort Worth: Synergetic Press, 1985), pp. 51–56.
 In developing a ‘microontology’ of life, Hird and Clark argue that certain theories of human-microbe relations fail to acknowledge that such relations do not operate with equal potency in both directions. Microbial life preceded human life by billions of years, provided the biological machinery from which all ‘complex’ life emerged, and, in all likelihood will continue to exist after humanity has vanished. Importantly, microbial life can be viewed as engaging in subtending relations ‘in which one realm or field of existence [the microbial] provides the conditions of possibility for that which emerges out of it or comes to pass within it [the human]’. Nigel Clark and Myra J. Hird, ‘Microontologies and the Politics of Emergent Life’, in Handbook on the Geographies of Power, ed. by Matt Coleman and John Agnew (Cheltenham: Edward Elgar, 2018), pp. 245-258. See also Myra Hird, The Origins of Sociable Life: Evolution After Science Studies (Basingstoke: Palgrave, 2009), pp. 21-57.
 Scott Gilbert et al., ‘A symbiotic view of life: we have never been individuals’, The Quarterly Review of Biology 87 (2012): 325-341.
 Bruno Latour, ‘A Plea for Earthly Sciences’, in New Social Connections, ed. by J. Burnett, S. Jeffers and G. Thomas (London: Palgrave Macmillan, 2010), pp. 72-84 (p. 75).
 See Timothy Morton: ‘Ecological facts [amongst which I include antimicrobial resistance] are, at present, very often facts about the unintended consequences of our actions’ (Morton, Being Ecological (London: Pelican, 2018) p. 16).
 Hannah Landecker, ‘Antibiotic Resistance and the Biology of History’, Body & Society, 22:4 (2016): 19-52.
 See Melinda Cooper’s chapter ‘Preempting Emergence’ in her Life as Surplus (Seattle: University of Washington Press, 2008), pp. 74-101.
 Melinda Cooper summarises these processes, in which bacteria share genetic material horizontally (in contrast to the vertical transmission that limits genetic propagation in most animals): ‘It has been known, since the late 1950s, that bacteria are able to exchange sequences of DNA, often between unrelated species, through a general process of horizontal transfection. Only recently has the full extent of this mobility become apparent: Under certain conditions mobile sequences of bacterial DNA jump across species, genuses, and kingdoms; once integrated into a new genome, these sequences are able to mutate and recombine; the bacterial genome itself is highly fluid, capable of mutating under stress and accelerating its own mutation rate. While many leading infectious disease specialists continue to see microbial resistance as a form of (highly accelerated) Darwinian evolution, a growing body of new research is suggesting that bacteria do not even have to wait around for random mutation to confer resistance; they can share it among themselves. The new microbiology is discovering that for bacteria resistance is literally contagious’ (Life as Surplus, p. 77).
 Peter Mahon, Posthumanism: A Guide for the Perplexed (London: Bloomsbury, 2017), p. 70.
 Stefan Herbrechter, ‘Microbes’, in The Edinburgh Companion to Animal Studies, ed. by Lynn Turner, Undine Sellbach and Ron Broglio (Edinburgh: EUP, 2018), pp. 354-366 (p. 356). Herbrechter notes that he adopts the term ‘pharmakon’ with reference to Jacques Derrida’s usage of it (cf. Dissemination (London: Continuum, 2004 )).
 The latest being the ‘CRISPR-cas’ system, a ‘programmable’ system, harnessed from microbial immune systems, that allows for precise changes to be introduced into target DNA sequences. See Mahon, Posthumanism, pp. 71-79.