When the Spanish arrived in the New World, they conquered great empires through a combination of Guns, Germs, and Steel — but mainly germs:
In 1519, when forces led by Spanish conquistador Hernando Cortés arrived in Mexico, the native population was estimated at about 25 million. A century later, after a Spanish victory and a series of epidemics, numbers had plunged to around 1 million.
The largest of these disease outbreaks were known as cocoliztli (from the word for ‘pestilence’ in Nahuatl, the Aztec language). Two major cocoliztli, beginning in 1545 and 1576, killed an estimated 7 million to 18 million people living in Mexico’s highland regions.
“In the cities and large towns, big ditches were dug, and from morning to sunset the priests did nothing else but carry the dead bodies and throw them into the ditches,” noted a Franciscan historian who witnessed the 1576 outbreak.
There has been little consensus on the cause of cocoliztli — although measles, smallpox and typhus have all been mooted. In 2002, researchers at the National Autonomous University of Mexico (UNAM) in Mexico City proposed that a viral haemorrhagic fever, exacerbated by a catastrophic drought, was behind the carnage2. They compared the magnitude of the 1545 outbreak to that of the Black Death in fourteenth-century Europe.
A couple new studies point to salmonella:
In an attempt to settle the question, a team led by evolutionary geneticist Johannes Krause at the Max Planck Institute for the Science of Human History in Jena, Germany, extracted and sequenced DNA from the teeth of 29 people buried in the Oaxacan highlands of southern Mexico. All but five were linked to a cocoliztli that researchers think ran from 1545 to 1550.
Ancient bacterial DNA recovered from several of the people matched that of Salmonella, based on comparisons with a database of more than 2,700 modern bacterial genomes.
Further sequencing of short, damaged DNA fragments from the remains allowed the team to reconstruct two genomes of a Salmonella enterica strain known as Paratyphi C. Today, this bacterium causes enteric fever, a typhus-like illness, that occurs mostly in developing countries. If left untreated, it kills 10–15% of infected people.
It’s perfectly reasonable that the bacterium could have caused this epidemic, says Schroeder. “They make a really good case.” But María Ávila-Arcos, an evolutionary geneticist at UNAM, isn’t convinced. She notes that some people suggest that a virus caused the cocoliztli, and that wouldn’t have been picked up by the team’s method.
Krause and his colleagues’ proposal is helped by another study posted on bioRxiv last week, which raises the possibility that Salmonella Paratyphi C arrived in Mexico from Europe.
A team led by Mark Achtman, a microbiologist at the University of Warwick in Coventry, UK, collected and sequenced the genome of the bacterial strain from the remains of a young woman buried around 1200 in a cemetery in Trondheim, Norway. It is the earliest evidence for the now-rare Salmonella strain, and proof that it was circulating in Europe, according to the study.
If you read the firsthand account of The Discovery And Conquest Of Mexico by Bernal Diaz Del Castillo — and I highly recommend that you do! — he mentions smallpox specifically five separate times:
Xicotencatl made various other offers of his services in the name of his country. This Xicotencatl was a tall man, broad shouldered, and well built, with a large fresh coloured face, full of scars, as if pitted with the smallpox. He may have been about thirty-five years of age, and was earnest and dignified in his deportment. Cortes thanked him most sincerely, saying, ” he would acknowledge them as vassals of our emperor, and would, for the future, look upon them as our friends.
But to return to Narvaez. He happened to have a negro servant with him ill with the smallpox, through whom this terrific disease, which, according to the accounts of the inhabitants, was previously unknown in the country, spread itself through New Spain, where it created the greater devastation, from the poor Indians, in their ignorance, solely applying cold water as a remedy, with which they constantly bathed themselves; so that vast numbers were cut off before they had the blessing of being received into the bosom of the Christian church.
About this time another king had been raised to the throne of Mexico, as the former, who beat us out of the town, had died of the smallpox. The new monarch was a nephew, or, at least, a very near relative of Motecusuma, and was called Quauhtemoctzin. He was about twenty-five years of age, and a very well-bred man for an Indian. He was likewise a person of great courage, and soon made himself so greatly feared among his people that they trembled in his presence. His wife was one of Motecusuma’s daughters, and passed for a great beauty among her countrywomen.
This expedition was attended by many beneficial results ; for the whole country was thereby tranquilized, while it spread a vast idea of Cortes’ justice and bravery throughout the whole of New Spain; so that every one feared him, and particularly Quauhtemoctzin, the new king of Mexico. Indeed Cortes’ authority rose at once to so great a height, that the inhabitants came from the most distant parts to lay their disputes before him, particularly respecting the election of caziques, right of tenure, and division of property and subjects. About this time thousands of people were carried off by the smallpox, and among them numbers of caziques ; and Cortes, as though he had been lord of the whole country, appointed the new caziques, but made a point of nominating those who had the best claim.
On our arrival in Tlascalla, we found that our old friend Maxixcatzin, one of his majesty’s most faithful vassals, was no more, he having died of the smallpox. We were all sorely grieved at this loss, and Cortes himself, as he assured us, felt it as much as if he had lost his own father. We put on black cloaks in mourning for him, and paid the last honours to the remains of our departed friend, in conjunction with his sons and relations.
My reaction to that book, by the way, was, Why didn’t we read this in school?
Real history is nothing like school history. Oddly, real history is more like a swords-and-sorcery novel: evil priests, hair matted with blood, commit human sacrifices atop pyramids amidst a city built on a lake inside a volcanic crater; frenzied fighting ensues.