The Tangled Tree by David Quammen

Author:David Quammen
Language: eng
Format: epub, mobi
Publisher: Simon & Schuster

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During the late 1960s and early 1970s, scientists began to realize that the implications of horizontal gene transfer go far beyond the problem of bacterial resistance to antibiotics. Those implications include the whole matter of how evolution works—by Darwinian mechanisms, or otherwise?—and how it has worked for much of the past four billion years. A British bacteriologist named Ephraim S. Anderson hinted at this in 1968.

Anderson, born in 1911, came from an Estonian Jewish immigrant family in a working-class neighborhood of Newcastle upon Tyne, an unadvantaging start for an aspiring British scientist in the hard years between the world wars. He showed his brilliance in school, won a scholarship to study medicine, then struggled to find work, disfavored for at least some positions because he was a Jew. He joined the Royal Army Medical Corps and spent five years in Cairo, Egypt, tracing typhoid outbreaks among British troops. Returning to England, he took a research job at the Enteric Reference Laboratory, a national facility with a practical mission: identifying and characterizing strains of intestinal bacteria that threaten human health. Within a few years, Anderson became its director. By then, he was an expert on enteric bacteria such as the Salmonella group, which includes the typhoid bug, and during the 1960s he emerged as an influential voice on public health, warning early and loudly about the dangers of antibiotic resistance. He was known for his brusqueness, his feistiness, his “great gift” for rubbing people the wrong way, and for his strong opposition to the routine use of antibiotics for growth promotion in livestock. He was among the earliest bacteriologists in England who recognized what Watanabe and his Japanese colleagues had seen: that resistance genes could spread quickly, from strain to strain, from species to species, on plasmids. For that alone, he would be notable. But in one of his journal papers, Anderson went a step further, speculating that another important effect of such transfer factors “is their possible importance in bacterial evolution in general.”

The fact that resistance genes could move sideways so easily was a clue that genes for other traits might be moving too. And so, Anderson wrote, “the temptation is very strong to suggest that the transfer factors may have influenced bacterial evolution.” Maybe it wasn’t all just a matter of mutation and natural selection after all. Maybe horizontal gene transfer also played a big role in the long history of microbial life.

This was a gentle statement of a revolutionary prospect. Was the history of evolution—at least among one group, the bacteria—really that different from Darwin’s theory as we have come to embrace it?

Anderson’s suggestion was echoed in 1970 by a pair of British researchers in a different area of bacteriology. Dorothy Jones and Peter Sneath were microbial systematists—namers and classifiers—at the University of Leicester. They worked in the same long tradition as Ferdinand Cohn, the great early classifier of bacteria, but with a concerted effort to make use of new data, modern methods, and fresh thinking. Their preferred

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