February 02, 2013

Aztec conquest of Xaltocan led to population replacement

This study represents a good example of how ancient DNA analysis can supplement traditional archaeology. Issues of population replacement/continuity are often encountered in archaeology, especially when there are traditions of conquest/resettlement, or such events might be hypothesized by changes in the material record.

But, such events are often difficult to interpret, because people living through periods of turmoil might have a tendency to exaggerate their importance, while culture is malleable and may shift without large-scale population replacement.

Am J Phys Anthropol DOI: 10.1002/ajpa.22152

The Genetic Impact of Aztec Imperialism: Ancient Mitochondrial DNA Evidence From Xaltocan, Mexico 

Jaime Mata-Mıguez et al.

In AD 1428, the city-states of Tenochtitlan, Texcoco, and Tlacopan formed the Triple Alliance, laying the foundations of the Aztec empire. Although it is well documented that the Aztecs annexed numerous polities in the Basin of Mexico over the following years, the demographic consequences of this expansion remain unclear. At the city-state capital of Xaltocan, 16th century documents suggest that the site's conquest and subsequent incorporation into the Aztec empire led to a replacement of the original Otomí population, whereas archaeological evidence suggests that some of the original population may have remained at the town under Aztec rule. To help address questions about Xaltocan's demographic history during this period, we analyzed ancient DNA from 25 individuals recovered from three houses rebuilt over time and occupied between AD 1240 and 1521. These individuals were divided into two temporal groups that predate and postdate the site's conquest. We determined the mitochondrial DNA haplogroup of each individual and identified haplotypes based on 372 base pair sequences of first hypervariable region. Our results indicate that the residents of these houses before and after the Aztec conquest have distinct haplotypes that are not closely related, and the mitochondrial compositions of the temporal groups are statistically different. Altogether, these results suggest that the matrilines present in the households were replaced following the Aztec conquest. This study therefore indicates that the Aztec expansion may have been associated with significant demographic and genetic changes within Xaltocan.



terryt said...

"these results suggest that the matrilines present in the households were replaced following the Aztec conquest".

That does indicate major replacement. I would expect males to be replaced but females to be adopted into incoming groups.

Rob said...

whether mtDNA or Y DNA, the fact that the occupants spread couple hundred years apart should not be too suprising. We dont know what kind of tenorial systems they had, nor what kind of settlement mobility. Looks like too many assumptions made , but certainly, they could be correct tho.

fmgarzam said...

Eugenics should be considered a possibility. I learned a little bit about the Aztecs from a local university Professor. Even tough my late friend and I usually discussed postConquest New Spain, the first Viceroy’s brilliant tenure, he always described his admiration for the Aztecs (we hardly know about them here in Northern Mexico). He saw them as ruthless disciplinarians, so well organized that German Hasburg Catille’s conquistadores just took over their political system. He even saw some Nazi like features there. Ethnic cleansing might have been possible then.
I like to see them more Asian like, as DNA shows, as well as for their way of living in their high altitude Venice like lake stronghold. I see them, perhaps, more Singapore like.

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