Latin Americans show widespread Mediterranean and North African ancestry

Recent preprint Latin Americans show wide-spread Converso ancestry and the imprint of local Native ancestry on physical appearance, by Chacon-Duque et al. bioRxiv (2018).

Abstract:

Historical records and genetic analyses indicate that Latin Americans trace their ancestry mainly to the admixture of Native Americans, Europeans and Sub-Saharan Africans. Using novel haplotype-based methods here we infer the sub-populations involved in admixture for over 6,500 Latin Americans and evaluate the impact of sub-continental ancestry on the physical appearance of these individuals. We find that pre-Columbian Native genetic structure is mirrored in Latin Americans and that sources of non-Native ancestry, and admixture timings, match documented migratory flows. We also detect South/East Mediterranean ancestry across Latin America, probably stemming from the clandestine colonial migration of Christian converts of non-European origin (Conversos). Furthermore, we find that Central Andean ancestry impacts on variation of facial features in Latin Americans, particularly nose morphology, possibly relating to environmental adaptation during the evolution of Native Americans.

latin-america-finestructure
Reference population samples, fineSTRUCTURE groups and SOURCEFIND ancestry estimates for the five Latin American countries examined. (A) Colored pies and grey dots indicate the approximate geographic location of the 117 reference population samples studied. These samples have been subdivided on the world map into five major biogeographic regions: Native Americans (38 populations), Europeans (42 populations), East/South Mediterraneans (15 populations), Sub-Saharan Africans (15 populations) and East Asians (7 populations). The coloring of pies represents the proportion of individuals from that sample included in one of the 35 reference groups defined using fineSTRUCTURE (these groups are listed in the color-coded insets for each region; Supplementary Fig. 2). The grey dots indicate reference populations not inferred to contribute ancestry to the CANDELA sample. Panels (B) and (C) show, respectively, the estimated proportion of sub-continental Native American and European ancestry components in individuals with >5% total Native American or European ancestry in each country sampled (the stacked bars are color-coded as for the reference population groups shown in the insets of panel (A)). Panel (D) shows boxplots of the estimated sub-continental ancestry components for individuals with >5% total Sephardic/East/South Mediterranean ancestry. In this panel colors refer to countries as for the colored country labels shown in (A).

I don’t know how I missed this. It is probably the biggest sample of Latin American populations used for genetic analysis, and it seems it is due for publication soon.

One of its most interesting finds is the eastern Mediterranean and North African ancestry found in almost a quarter of the individuals sampled all over Latin America, which the authors attribute to Sephardic Jews or Conversos.

Although these Conversos were forbidden from migrating to the colonies, historical records document that some individuals made the journey, in an attempt to avoid persecution14. Since this was a clandestine process, the extent of Converso migration to Latin America is poorly documented. Genetic studies have provided suggestive evidence that certain Latin American populations, arguably with a peculiar history, could have substantial Converso ancestry1,18. Our findings indicate that the genetic signature of Converso migration to Latin America is substantially more prevalent than suggested by these special cases, or by historical records.

However, strictly speaking, Converso refers to a recent convert, while this ancestry could have also been part of older Sephardic (and obviously other North African) admixture found in Iberian populations during the Reconquista.

latin-america-native-spanish-conversos
Geographic variation of Native American (A), European (B), and East/South Mediterranean (C) ancestry sub-components in Latin American individuals. Each pie represents an individual with pie location corresponding to birthplace. Since many individuals share birthplace, jittering has been performed based on pie size and how crowded an area is. Pie size is proportional to total continental ancestry and only individuals with >5% of each continental ancestry are shown. Coloring of pies represents the proportion of each sub-continental component estimated for each individual (color-coded as in Fig. 1; Chaco2 does not contribute >5% to any individual and was excluded). Pies in panel (C) have been enlarged to facilitate visualization.

Discovered via Lizzie Wade’s article Latin America’s lost histories revealed in modern DNA, Science (2018).

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