In:
Science, American Association for the Advancement of Science (AAAS), Vol. 380, No. 6645 ( 2023-05-12)
Abstract:
Between 1100 and 900 years ago, a global warming episode affected numerous civilizations worldwide. In the Americas, severe droughts reconfigured the demography of pre-Hispanic civilizations as well as the ecological landscape. We report ancient genomic data from 12 pre-Hispanic individuals from before and after this climate change episode to investigate the population dynamics at the limit between the two biocultural regions of Aridoamerica in the north and Mesoamerica in central and south Mexico. RATIONALE The archaeological evidence indicates that the droughts shifted the border southward between desertic Aridoamerica and the verdant and culturally rich Mesoamerica, which was home to large civilizations like the Aztecs and Mayans. This climate change allegedly led to a population replacement in the northern frontier of Mesoamerica by seminomadic hunter-gatherers from Aridoamerica. However, this hypothesis relies solely on archaeological data, so we generated ancient genomic and mitochondrial DNA data to test it. In addition, we leveraged these data to describe the ancient population structure of Mexico and to investigate the contribution of unsampled genetic lineages to the ancient genomes. RESULTS The pre-Hispanic population structure closely resembles the structure observed in present-day Mexico, which clearly differentiates northern and central Indigenous populations. This reflects an overall conservation of the genetic structure of the populations inhabiting the Mexican territory for at least 1400 years (which is the date of the most ancient individual in our study). We found genetic continuity in the ancient individuals from before and after the climate change episode. This contradicts the hypothesis of population replacement by Aridoamerican groups in this region and suggests that the local population stayed in their homeland despite the long-standing droughts. The population continuity at the studied site can be explained by the favorable location in the high and humid Sierra Gorda mountain range and the fact that cinnabar mining was the main economic activity, not agriculture. We identified the contribution of two distinct unsampled “ghost” genetic ancestries to pre-Hispanic populations of northern and central Mexico, respectively. Whereas the unsampled genetic ancestry contributing to the northern genome coincides with one previously identified in a present-day population from south Mexico, the second ghost genetic ancestry was previously unknown. CONCLUSION The ancient genomes revealed a conservation of the genetic structure in Mexico in the past 1400 years and population continuity in the northern frontier of Mesoamerica despite the severe droughts 1100 years ago. It is likely that the mining-based economy allowed the population to subsist in their homeland during this climate change period when the border between Aridoamerica and Mesoamerica shifted southward. The identification of a new ghost genetic ancestry (UpopA2), along with that observed in ancient Sierra Tarahumara and present-day Mixe (UPopA), reveals a complex population history in the late Pleistocene in the Americas. The recovery and study of ancient genomes from Mexico, conducted ethically, can help fill important gaps in our understanding of the deep population history of the Americas. Population continuity and ghost genetic ancestries in pre-Hispanic Mexico. Ancient individuals who inhabited the northern frontier of Mesoamerica (NFM) before and after a 200-year period of severe droughts (shown in timeline) belong to a continuous population. This is in contrast to a previous hypothesis suggesting that hunter-gatherers from Aridoamerica replaced the populations at the NFM following the southward shift of its limits with Mesoamerica (solid and dashed lines). Individuals from Sierra Tarahumara and Cañada de la Virgen show genetic ancestry from two distinct ghost populations (UpopA and UpopA2).
Type of Medium:
Online Resource
ISSN:
0036-8075
,
1095-9203
DOI:
10.1126/science.add6142
Language:
English
Publisher:
American Association for the Advancement of Science (AAAS)
Publication Date:
2023
detail.hit.zdb_id:
128410-1
detail.hit.zdb_id:
2066996-3
detail.hit.zdb_id:
2060783-0
SSG:
11
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