I reached out to Dr. Jill Banfield, a geomicrobiologist at the University of California, Berkeley, because my fieldwork among human microbiome researchers had made me curious about the early history of life on Earth.

Could I engage her in a conversation?

I reached out, as well, because I was curious about the curatorial logic with which she had arranged the sites she studied: the Atacama Desert, the geysers of Wyoming, hot vents buried deep in the oceans, acidic mines pitches in Australia and Colombia, hypersaline lakes, and the human gut. What did these disparate landscapes have in common?

“Would it be fair to say that your research is focused on microbes in extreme environments?”

“No, I don’t approve of this phrasing,” she replied. “These environments are only extreme from a human perspective. For microbes, they are not extreme at all.”

For microbes. The phrase kept working on me long after I left her lab.

When I first reached out, Jill had hesitated to talk to me. Without engaging in any unnecessary niceties, she shared that she was not very interested in things human.

“Why not?” I wanted to know.

“Humans are not very interesting,” she replied. “Their importance for Earth or for life is not very significant, except perhaps in negative terms.”

For microbes. The longer I thought about Jill’s formulation, the more I was intrigued by the shift in perspective that emerged from it. What gripped Jill was the possibility of telling the microbial history of planet Earth, a history that not only dramatically exceeds any human time-scale; it also shrinks humans, documents them as an irrelevant, if unfortunate––destructive––side note to a singularly beautiful story of world-making.

If I was intrigued by Jill’s microbial antihumanism, this was not least because it seemed to open up the possibility of an anthropology that neither revolves around nor grounds itself in humans. Could I, as someone trained to study how humans make worlds (read: culture, society, history, politics) enter this microbial world and explore what notion of the human would emerge from it?

* * *

To conduct an anthropology of microbiology generally means to render visible the knowledge produced by microbiologists in human terms: to follow the humans that build the field, conduct experiments, make discoveries, apply for grants, engage in intrigues. It means to show that microbiology is a human practice, indebted to cultural forms and contingent on the social circumstances in which it is carried out.

The microbial worlds explored by microbiologists rarely come into view, as this would imply buying into science, losing sight of its contingency on the human.

The flipside of anthropology’s humanism, itself a reflection of the modern figure of the human as Man that emerged in seventeenth- and eighteenth-century Europe, is that it amounts to an exquisite (and unnecessary) epistemic poverty: all that the human sciences ever make visible is—the human.

How can anthropology, how can the human sciences escape the human? How can anthropologists enter the space for microbes? And how can they do so without abandoning anthropology and simply replacing it with microbiology?

More provocatively: hasn’t the world outgrown the figure of the human on which anthropology remains contingent? Isn’t “the human” by now an unfortunate, destructive anachronism?

* * *

I learn from Jill Banfield and other microbiologists that Earth is a microbial planet, formed and shaped by microbes over long stretches of time.

The first microorganisms, single-cell prokaryotes known as cyanobacteria, emerged about 3.5 billion years ago. For the next 2.5 billion years, they were the only life form on Earth and they gradually, haphazardly produced the biosphere on which all life is contingent.

Then as now, bacteria produce the oxygen we breathe. Then as now, they run the biogeochemical cycle on which all life on Earth depends.

Every multicellular form of life emerged from microbes and evolved in conversation with microbes and the molecules they produce.

The unusual status of Earth in our solar system, with respect to billions of other solar systems, as far as we can tell––is due to microbial life.

And the human?

If looked at in terms of our microbial planet, humans are late, chance descendants of microbial evolution, adapted to and contingent on a microbial world, inseparably interwoven with the microbial environment. From our brains to our circadian rhythm, from our metabolism to our immune system, from embryogenesis to heart rate, insulin level, or the clotting of our blood–– there appears to be no aspect of our physiology that is not contingent on the microbes that live in and on us.

The consequences of thinking from within the space that Jill reserved for microbes thus couldn’t be more far-reaching. Indeed, from the perspective of microbiology, the figure of the human as such—that figure on which all of the human sciences are contingent—does not exist. It is at best a sterile abstraction, as if the human sciences had cut out a slice of the (microbial) wild, put it in a Petri dish, and added bleach and antibiotics until nothing but a dead (sterile) mass was left: the human as such.

“We think about ourselves as having microbes,” Jill told me in our most recent conversation. “But really, it is much more plausible to me to think that microbes invented us as a habitat in which they cannot only survive but flourish.”

For Jill, humans are an environment invented by bacteria—for bacterial ends.

* * *

What would it take to seriously, stubbornly, rethink and rearticulate the human—all of it—in terms of the microbial unfolding of the world?

Not because microbiology is the decisive breakthrough to the truth (as if, at last, we found the really real). But rather because microbiology offers a possibility, one among several, for exploring possibilities of being human after “the human.”

Couldn’t one understand and practice anthropology as a ceaseless empirical exercise in deanthropologization? Not only with respect to microbes, but also with respect to . . . ?