From Victorian England to contemporary America, creationists have often denied that we are related to other primates. But the hard truth of our genealogy does even greater damage to human pride. We are cousins of every living thing, including the billions of E. coli bacteria in our intestines. This kinship may not be flattering, but it is useful. By studying these tiny creatures, we learn about other organisms, including ourselves. As the French biologist Jacques Monod once said, “What is true for E. coli is true for the elephant.”
Carl Zimmer effectively applies this principle in his engrossing new book, “Microcosm,” relating the study of these microbes to larger developments in biology and thoughtfully discussing the social implications of science. If you must limit yourself to only one title on bacteria this year, “Microcosm” is a good pick.
As Zimmer explains, a number of landmark discoveries have involved E. coli, including experiments confirming the universality of biochemistry and revealing how genes function. Studying the many strains of E. coli (most are innocuous) suggests something further: the divergent behavior of genetically identical bacteria, Zimmer writes, is “a warning to those who would put human nature down to any sort of simple genetic determinism.”
Along with some more familiar material, Zimmer vividly describes the unfamiliar microscopic world of E. coli and their tightly packed, rod-shaped bodies: “If you prick us, we bleed, but if you prick E. coli, it blasts.” And unlike mammals, bacteria often swap genetic material, placing limits on Monod’s dictum. However, species large and small absorb DNA from viruses. For E. coli and humans alike, Zimmer emphasizes, “there are no fixed essences in life.”
“Microcosm” also examines E. coli’s contentious public life. Creationists claim its tail-like, propulsive flagellum is proof of someone’s intentional design. But at the 2005 trial over the teaching of “intelligent design” in Dover, Pa., scientists showed that the flagellum is not inexplicably complex. The resistance some E. coli have developed to antibiotics (whose limits are given their own slightly disquieting chapter) provides yet more evidence for evolution.
In the 1970s, tinkering with E. coli helped scientists learn to manipulate genes, making the bacterium, Zimmer says, “the monster and the mule” of bioscience — a symbol of fears about genetic experimentation, as well as a workhorse used to make drugs. Here, he calmly finds a middle ground. While these initial concerns have remained largely unrealized, “genetic engineering has fallen far short of the more extravagant promises” about the eradication of major diseases that were offered 30 years ago.
Broadly, Zimmer sees public tolerance for genetic engineering increasing as science further reveals our patchwork genomic cloth. “New research on human evolution,” he writes, “makes it impossible to believe that a thing either is or is not a whole human being,” as some conservative opponents of biomedical inventions have argued. If our attempts to define a uniquely human core are arbitrary, however, they help us decide how to live. Zimmer thus hopes a debate over genetic engineering will produce a “deeper understanding of what it means to be human: not as an inviolable essence but as a complex cloud of genes, traits, environmental influences and cultural forces.”
Desirable as this discussion sounds, is it likely? As Zimmer notes, a bit too briefly, the emergence of biotechnology as an economic force dampened this debate three decades ago. Still, some public advocacy groups remain wary of bioscience, and coming innovations could revive opposition from cultural conservatives, rights-based interest groups and liberals upset at the uneven distribution of these goods. Genetic engineering and new forms of biomedicine could therefore engender a worthy civic dialogue or aggravate old political fractures. Or biotechnology may simply roll on. In any case, Zimmer adroitly links the common heritage we share with E. coli and the emerging horizons of science: “Through E. coli we can see the history of life, and we can see its future as well.”
