The turkey out of the Americas: two indigenous domestications, one of which fed the world
The only large livestock animal the Americas domesticated was domesticated twice, independently, by indigenous peoples - once in Mesoamerica and once in the US Southwest - and ancient DNA says the two stocks never mixed. The bird Spaniards carried to Europe in the early sixteenth century, and which came back to North America as the commercial turkey, is the Mesoamerican one. The earliest Spanish page describing it records it being handed over on Cozumel in 1518.
Why this wins its question: The standard English sentence is that Spaniards brought the turkey from Mexico to Europe, and it stops there. This object supplies what that sentence leaves out and can be checked: the sample counts and the haplogroup behind the claim of two independent indigenous domestications, the isotopic evidence that Mesoamerican turkeys were being fed maize, the finding that no maternal lineage is shared between the two centres, the researchers' own statement of what remains unresolved, and the earliest Spanish page that describes the bird - with the armed entrada and the discontented crew printed next to the gift, rather than cropped out of it.
Claims
Every assertion below is bound to registered sources and carries its own confidence. Weight them; do not treat the page as uniformly authoritative.
A 2010 study in the Proceedings of the National Academy of Sciences sequenced ancient mitochondrial DNA from 149 turkey bones and 29 coprolites recovered at 38 archaeological sites and spanning 200 BC to AD 1800. It found a single dominant maternal lineage, designated haplogroup H1, in more than 85 per cent of the samples that sequenced successfully, with 116 of 143 archaeological samples carrying one identical haplotype - a degree of uniformity the authors read as a distinct domestic breed in the precontact Southwestern United States.
The same study concluded that there were at least two occurrences of turkey domestication in precontact North America, and specifically ruled out the South Mexican domestic turkey, Meleagris gallopavo gallopavo, as the progenitor of the Southwestern birds - which descend instead from wild populations of the Eastern and Rio Grande type.
Work published in Royal Society Open Science in 2018 analysed 55 archaeological turkey remains from 14 sites between northern Mexico and the Yucatan peninsula, 53 of them large enough for both isotopic and genetic analysis, and identified three taxa in the assemblage - Meleagris gallopavo mexicana, M. gallopavo gallopavo and the ocellated turkey M. ocellata - which is to say that Mesoamerican peoples were handling several local populations rather than one.
The isotopes in that Mexican assemblage record a spread of husbandry rather than a single practice: feeding behaviours range from wild foraging through mixed ecologies to heavy provisioning with maize or other C4 plants, with the enrichment strongest in Postclassic birds. Captive rearing is visible as early as the Preclassic, though on a small scale.
No maternal haplotypes were found to be shared between the Mesoamerican and the Southwestern assemblages. The two domestications are therefore independent in the strong sense: not one tradition spreading north, but two, with no living birds demonstrably moving between them.
The 2018 authors state their own limits, and they are worth carrying: the overall chronology of human intervention, and the number of wild progenitor populations that contributed to the domestic stocks, remain unanswered questions. Dates for a first domestication should be read against that, not as settled.
The earliest layer of the Spanish written record already describes the bird as kept and given. Oviedo, in book XVII chapter IX of his Historia general y natural de las Indias, recounts that on Cozumel in 1518, after the chaplain of Juan de Grijalva's fleet had said mass on the top of a stone tower, "truxeron los indios al capitan ciertas gallinas de las de aquella isla, que son grandes, como pavos, e no de menos buen gusto, e vasijas de miel, e se lo presentaron" - the Indians brought the captain certain hens of that island, large as peacocks and of no worse flavour, and jars of honey, and made him a present of them. The following page names them again as "aquellos pavos o gallinas grandes".
The setting of that gift belongs in the record beside it. The same chapter has the captain take formal possession of the tower under the royal banner, and then proclaim ordinances on pain of penalties: that none of his men should do the Indians harm or injury, anger them, mock them, speak with the women, or take anything from them against their will, and that anyone finding an Indian willing to trade gold, pearls or precious stones should bring him to the captain. Oviedo adds that the proclamation "no plugo a todos los que oyeron el pregon: antes muchos se resabiaron e quedaron mal contentos del capitan" - it did not please everyone who heard it; many took it badly and were left discontented with their captain.
Mexican turkeys were transported to Europe in the early sixteenth century after Spanish contact, and modern commercial turkeys descend from that Mesoamerican stock, which was carried back across the Atlantic to North America in the eighteenth century. The bird now farmed in the country where the second domestication happened is the descendant of the first.
The credit usually handed to Spanish transport therefore attaches to only one of the two American domestications, and to the carriage rather than to the animal: the achievement being moved was indigenous, and it was already several centuries old when it was moved. What became of the Southwestern domestic breed after contact is not established by the sources read here and is not asserted; the archaeological series that defines it ends at about AD 1800.