Cosmic Apprentice: Dispatches from the Edges of Science (3 page)

PART I

FROM “PROTOZOAN” TO POSTHUMAN

CHAPTER 1

THE HUMAN IS MORE THAN HUMAN

Interspecies Communities and the New Facts of Life

MOTLEY CREWS

“This universe,” says the physicist Richard Feynman, “just goes on, with its edge as unknown as the bottom of the bottomless sea . . . just as mysterious, just as awe-inspiring, and just as incomplete as the poetic pictures that came before. But see that the imagination of nature is far, far greater than the imagination of man. No one who did not have some inkling of this through observation could ever have imagined such a marvel as nature is.”
1

Well, it is to this universe that I want to turn again, and to a specific part of it. I want to turn to life, and within that part a fascinating subsystem, the one in which, of course, we are most interested: ourselves. Yet there is a paradox that precisely the nonanthropic, the nonhuman, the posthuman, the transhuman, the more-than-human, the animal has recently captivated the interest of anthropologists, whose ostensible focus is precisely
anthropos,
the human.

It might be called the paradox of exclusion, or even the return of the repressed. We see it in quantum mechanics, in the recognition of the role of, or the need to take account of, the experimental apparatus, the experimenter’s decisions (what Karen Barad calls “the agential cut”) in making a measurement.
2
We see it in thermodynamics, where descriptions of behavior in thermally sealed boxes were boldly extrapolated to the whole universe, thus predicted to undergo a “heat death,” the running out of energy. And we see it in genocentric biology, where Max Delbrück simplified the study of life by studying nonmetabolizing viruses of bacteria, so-called bacteriophages, to home in on the genetic mechanism.
3
In each case, simplifying assumptions or experimental designs blocking out most of the world not only reveal natural processes but are hastily applied beyond the limited arena in which they were developed. We are stressed by what is repressed. Anthropology—the study of human beings—obeys this same logic of the return of the ghost of what was excluded, in this case all the systems, living and nonliving, that make our kind possible.

But I think there is another reason, more specific to anthropology, for why “the nonhuman” is pressing. There are twice as many people on the planet today as when I was born. This is unsustainable. At this rate there will be 6.5 trillion of us by the year 2525—and 13.312 quadrillion by the year 3000, just around the corner in geological time.

Nicholas of Cusa said the universe is a sphere whose center is everywhere and circumference is nowhere. I don’t know about you, but that sounds about right. We love to think we are special, but the history of science suggests otherwise. Now the
anthropos,
the human itself, is coming under pressure.

Imagine that an alien penetrated the roof of this building, materializing from a scintillating beam of blue to train a cell gun on you. He, she, or it pulls the trigger. “You” begin to dematerialize. The beam annihilates every human cell in your body. Still, your form, like the recognizable smile of the Cheshire Cat, would persist:

Life deals in such mixed cultures. It has been working with crowds for billions of years. Most of the DNA of the trillions and trillions of cells in our bodies is not “ours” but belongs to cohabiting bacteria.

HYPERSEX AND FRENEMIES

Ten percent of our dry weight is bacteria, but there are ten of “their” cells in our body for every one of “ours,” and we cannot make vitamins
K
or
B12
without them. The maverick Russian geochemist Vladimir Vernadsky thought of life as an impure, colloidal form of water. What we call “human” is also impure, laced with germs. We have met the frenemy, and it is us.

But before leaving this point of the pointillist composition that is our Being made of beings, please notice that even those cells that
do not
swarm in our guts, on our skin, coming and going, invading pathogenically or aiding probiotically—please notice that even these very central
animal
cells, the differentiated masses of lung, skin, brain, pancreas, placental, and other would be
strictly human
tissues that belong to our body proper—even they are infiltrated, adulterated, and packed with Lilliputian others. The mitochondria, for example, that reproduce in your muscles when you work out come from bacteria.

We come messily from a motley. Indeed, we literally come from messmates and morphed diseases, organisms that ate and did not digest one another, and organisms that infected one another and killed each other and formed biochemical truces and merged. About forty genes are shared exclusively by humans and bacteria, suggesting they have been incorporated specifically into our genome.
5
Our guts are packed with bacteria whose aggregate microbiogenome has about 150 times more genes than “we” do, 3.3 million to our 23,000.
6
But
they,
though they come and go more easily than the rest of us, changing our mood and food, are also
us.
The immune system itself seems to be an evolved metasystem, a convoluted go-between, marshaling regulation and inflammation, and making sure that our animal cells and the rest of us—our bacteria and archaea—take it easy on each other.
7

Hypersex is a provisional name for the commingling of organisms that meet, eat, engulf, invade, trade genes, acquire genomes, and sometimes permanently merge.
8
Life displays mad hospitality. The Korean biologist Kwang Jeon of the University of Tennessee received in the 1970s a batch of amoebas infected with a deadly bacterial strain. Most died. In a set of careful experiments after culturing the survivor amoebas for several generations, he found that the survivors, with fewer bacteria per cell, could no longer live without their infection. Deprived of their new friends and former enemies, the nuclei would not function without micro-injections of bacteria into the cytoplasm. The sickness had become the cure; the pathogens had become organelles; the last had become the first.

Had Jeon, who was a Christian, witnessed speciation in the laboratory? It seems so. But it was not gradual, as neo-Darwinism predicts. It was near-instantaneous, the result not of mutations accumulating in a lineage but of transformative parasitism.

SYMBIOGENETICS

Peculiar behavior, you say? Not really. Considering that life has been growing on Earth for some 3.8 billion years, it is not surprising that life has grown into itself, eaten itself, and merged with itself. Crowd control has long been an issue. Radical solutions have long been the norm. In 2006 researchers at Texas A&M University and the University of Glasgow Veterinary School in Scotland reported in the
Proceedings of the National Academy of Sciences
that endogenous retroviruses called enJSRVs are essential for attachment of the placenta and therefore pregnancy in sheep. We are as pure as the driven slush.

Like bacteria, viruses “R” us: They have moved into our genomes. Viral structural proteins have been “hijacked” and integrated into mammal reproductive tissues, immune systems, and brains. Some retroviruses disable receptors that lead to infection by other retroviruses. There is no racial, let alone genetic, purity in life. At bottom we are part virus, the offspring not just of our parents but of promiscuous pieces of DNA and RNA. The road to humanity is paved with genetic indiscretions and transgressions, no less than sheep would not be sheep without their acquired enJSRV.

The symbiosis expert Margaret McFall-Ngai asked a roomful of doctors what it meant for our marine ancestors to be surrounded by all those germs—about a hundred million cells per liter. They had no answer, but she told them: She has proposed that the immune system evolved not to eliminate pathogens but to select for symbionts in the microbe-packed waters of our metazoan ancestors.
9
The immune system in its origin may thus be more like an employment agency, recruiting desired species, than like a national security state, recognizing and refusing entry to guard the fake purity of the Self.

Today it is widely recognized that the cells of animals were once a wild party of two if not three ancient beings: the oxygen-poisoned archaeon host, the oxygen-using bacteria that became mitochondria, and perhaps wildly squirming spirochetes, which abound in anaerobic environments. These wrigglers often penetrate their fellows, which have no immune systems. They feed at the edges, becoming snaky motors propelling their brethren, or take up residence inside them, wiggling happily ever after.

According to my mother, who’s been right before,
10
ancient bacterial symbioses gave our ancestors the intracellular motility abilities we see in mitosis and in the growth of undulating appendages. The creation of new symbioses by mergers on a crowded planet is called symbiogenesis. And we might call all aspects of its study “symbiogenetics”—the science of normative symbioses, the word commanding respect because of its apparent coinage from genetics; in fact, I derived it directly from symbiogenesis, though the connotation is a good one. Although this type of evolution sounds bizarre—a monstrous breach of Platonic etiquette in favor of polymorphous perversity—it is now confirmed by genetic evidence, taught in textbooks. It is a fact, or what the French philosopher of science Bruno Latour and the Belgian physicist-turned-philosopher Isabelle Stengers, not putting too fine a point on it, would call a factish. Nonetheless, although symbiogenesis—the evolution of new species by symbiosis—is now recognized, it is still treated as marginal, applicable to our remote ancestors but not relevant to present-day core evolutionary processes.

This is debatable. We are crisscrossed and cohabited by stranger beings, intimate visitors who affect our behavior, appreciate our warmth, and are in no rush to leave. Like all visible life-forms, we are composites. Near unconditional hospitality is necessary when we consider the sick factish that most of the human genome may be viral DNA.
11
Lactating women transfer their six hundred species of bacteria to their babies, as well as oligosaccharides their babies cannot digest but that feed certain bacteria. Bruce Sterling writes science fiction about humans engineered not to have any bacteria, but experiments with real mice deprived of their bacteria developed abnormal levels of immune system cells called invariant natural killer T cells that turned on their hosts, causing higher levels of inflammation, asthma, and inflammatory bowel disease. Although we are not mice, human studies show that early exposure to antibiotics is associated with asthma. The idea that we need to be pure and free of microbes to be healthy is as medically misguided as eugenicist dreams of triumph through racial homogeneity. Hundreds of species of fungi live in mammal guts despite or because of our immune systems. Indeed, scientists found that immune cells produce dectin-1, a protein that feeds skin fungi of mice; when they engineered the mice not to produce it, the mice experienced tissue damage from excess inflammation. It appears that our immune systems are designed not just to get rid of dangerous strangers but to entice needed others. No notion so disrupts the Pasteurian meme of health through biotic purity as the interest recently generated in fecal transplants, which have been declared safe in treating overgrowth of
Clostridium dificile
in patients needing to restore gut biota devastated from antibiotics, and are being investigated for the treatment of obesity. Another new medical approach is to develop skin creams that feed beneficial bacteria, warding off pathogens like
Staphylococcus aureus.
12

Of course these are medical avenues developing within a disease industrial complex that has long been in an emergency mode and makes its money from treatments. But symbiotic partnerships have the possibility not just to restore health but to improve it and alter us, to evolve us into new forms. I can envision future people with harmless luminous patches of bacteria, like tattoos but glowing in the dark, perhaps responding to mood or flashing like fireflies.

Some partnerships are fantastic. Luminous bacteria cram together to provide various marine animals with organs to light their way; deep-sea anglerfish females even use their shiny bacteria lights as lures to catch other fish. Luminescent bacteria, of the species
Vibrio fischeri,
provide the bobtailed squid,
Euprymna scolopes,
a nocturnal animal that feeds in the moonlight, so-called counterillumination: it projects light downward from its light organ, so it doesn’t show up as a tasty morsel outlined in silhouette for hungry predatory fish below.

Nestled within the chromosomes of some parasitic wasps lie bacteria. Multiple insect species transform because of
Wolbachia
bacteria. The genus is nearly ubiquitous in insect tissues. Too big to fit within the sperm of insects, infective
Wolbachia
can confer parthenogenesis on insect populations, that is, transform a population with two genders into one that is all females, this of course to the advantage of the “selfish” bacteria, as the sperm bottleneck impedes their propagation. By disabling the gender-bending bacteria, antibiotics can make separate species of jewel wasps interbreed again. More bizarre than the space aliens we imagine abducting and toying with us on their saucers, these gender-changing bacteria bring in suites of genes for metabolic and reproductive features as they establish symbioses, often permanent, in arthropods.