Sharon Begley
|
Jan 14, 2008 03:32 PM
Although the Europeans got silver, gold, converts and tobacco out of
their conquest of the New World in the 1500s, the Native Americans got
nothing but genocide, as what UCLA biologist Jared Diamond called “guns, germs and steel” killed an estimated 90 to 95 percent of the Native Americans—a
horrifying 20 million souls. Nothing was more one-sided than the
direction that germs traveled. European conquistadors thoughtfully
introduced smallpox, influenza and measles, against which the
populations of the Americas had no immunity. Result: disease killed
more of them than guns or steel.
Only one disease, scholars have long suspected, might have made the trip east to Europe: syphilis.
Circumstantial evidence supported an America-to-Europe trajectory: the
first recorded epidemic of syphilis occurred in Europe in 1495, upon
Columbus’s return. Although some medical historians have argued that the syphilis pathogen (the bacterium Treponema pallidum)
existed in Renaissance Europe long before Columbus returned from his
voyage to the New World, the most sophisticated study to date, being
published today in the journal PLoS Neglected Tropical Diseases,
concludes otherwise: a genetic analysis of the treponeme bacteria
supports the “Columbian theory” of syphilis’s origins in the Americas.
Call it Montezuma’s revenge, squared.
To trace the origins of syphilis, scientists have mostly studied old
bones, which preserve evidence of late-stage syphilis. But because it
is tough to pinpoint the exact age of the bones, these studies have
been inconclusive. Kristin Harper
of Emory University and colleagues therefore studied 21 genetic regions
in the genomes of 26 geographically disparate strains of treponemes.
Based on how much the different strains had diverged from the basic
genetic blueprint, the scientists were able to create a family tree for
treponemes. It showed that the strains that cause venereal syphilis
originated most recently. Their closest relatives were strains
collected in South America that cause the disease yaws. Together, they
say, the analyses supports the idea that syphilis originated in the
Americas.
But wait. The syphilis that was present in the Americas when
Columbus landed (there was a treponemal infection in the Dominican
Republic when he arrived) might not have been venereal—that is, spread
sexually. “Therefore, it is not clear whether venereal syphilis existed
in the New World prior to Columbus’s arrival,” write the scientists.
“While it is possible that Columbus and his crew imported venereal
syphilis from the New World to Europe, it is also possible that the
explorers imported a non-venereal progenitor that rapidly evolved into
the pathogen we know today only after it was introduced into the Old
World.” If so, then the Americas provided the ancestral germ, but that
germ assumed its deadly venereal form only after it became ensconced in
Europe.
Critics of the new study
say the analysis compared too few DNA sites to reach the conclusions it
did, arguing that “no evolutionary order” for the syphilis family of
bacteria can be inferred, and urging “caution” in accepting Harper’s
claim. Still, this study, combined with earlier work, presents the
strongest evidence that the Native Americans got at least a modicum of
revenge on their killers.
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