His­tory in the News

Sci­en­tists have sunk their teeth into new DNA anal­y­sis to ex­plain how mil­lions per­ished

History Revealed - - CONTENTS -

The head­lines in the his­tory world

From 1545-50, the Aztecs fell prey to one of his­tory’s dead­li­est epi­demics. It be­gan with blem­ishes or rashes on the skin, fevers, headaches and vom­it­ing, be­fore vic­tims started bleed­ing from the mouth, nose and eyes. Death fol­lowed within days. The mys­te­ri­ous dis­ease, named by the Aztecs as co­col­iztli (‘pesti­lence’), killed as many as 15 mil­lion peo­ple, or 80 per cent of the pop­u­la­tion.

It was only one of the out­breaks to oblit­er­ate the Aztec Em­pire since the ar­rival of Hernán Cortés in 1519, but the ex­act cause has never been de­ter­mined. A new study, pub­lished in the sci­en­tific jour­nal Na­ture Ecol­ogy and Evo­lu­tion, may re­veal a sig­nif­i­cant clue, though.

Sci­en­tists found traces of the bac­terium Sal­mo­nella en­ter­ica, which can cause fevers such as ty­phoid, in DNA ex­tracted from the teeth of 29 skele­tons buried in south­ern Mex­ico. It is the first di­rect ev­i­dence point­ing to a spe­cific cause.

The team – com­prised of re­searchers from the Max Planck In­sti­tute for the Sci­ence of Hu­man His­tory, Har­vard Univer­sity and the Mex­i­can Na­tional In­sti­tute of An­thro­pol­ogy and His­tory – used an ad­vanced screen­ing tech­nique, called MALT. This al­lowed them to test for any known pathogen, rather than test­ing for each in­di­vid­u­ally.

“This is a crit­i­cal ad­vance­ment in the meth­ods avail­able to us as re­searchers of an­cient dis­eases,” said Kirsten Bos, a mem­ber of the team. “We can now look for the molec­u­lar traces of many in­fec­tious agents in the ar­chae­o­log­i­cal record.”

While more re­search is needed, and sal­mo­nella can­not con­clu­sively be said to be the sole cul­prit, the find­ings are a com­pelling piece to the puz­zle.

CURSE OF CORTÉS Post­hu­mous den­tal work has shed light on the deadly out­break, one of many to plague the Aztecs af­ter the ar­rival of Hernán Cortés ( be­low)

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