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1. Colonialism, ethnogenesis, and biogeographic ancestry in the US Southwest

   https://doi.org/10.1002/ajpa.24380  

   Hunley, Keith ; Moes, Emily ; Edgar, Heather ; Healy, Meghan ; Mosley, Carmen ; Dixon, Aurelia ( August 2021 , American Journal of Physical Anthropology)

   Differences between self‐perceived biogeographic ancestry and estimates derived from DNA are potentially informative about the formation of ethnic identities in different sociohistorical contexts. Here, we compared self‐estimates and DNA‐estimates in New Mexico, where notions of shared ancestry and ethnic identity have been shaped by centuries of migration and admixture.

   We asked 507 New Mexicans of Spanish‐speaking descent (NMS) to list their ethnic identity and to estimate their percentages of European and Native American ancestry. We then compared self‐estimates to estimates derived from 291,917 single nucleotide polymorphisms (SNPs), and we examined how differences between the estimates varied by ethnic identity.

   Most NMS (94%) predicted that they had non‐zero percentages of European and Native American ancestry. Self‐estimates and SNP‐estimates were positively correlated (r_European = 0.38,r_{Native‐American} = 0.36,p < 0.001). The correlations belie systematic patterns of underestimation and overestimation based on ethnic identity. NMS with ancestral ties to 20th century immigrants, who identified as Mexican or Mexican American, often underestimated their European ancestry (self‐estimate < SNP‐estimate) and overestimated their Native American ancestry. The pattern was reversed for NMS who emphasized deep connections to colonial New Mexico and identified as Spanish or Spanish American.

   While NMS accurately predicted that they had European and Native American ancestry, they predicted ancestry percentages with only moderate accuracy. Differences between self‐estimated and SNP‐estimated ancestry were associated with ethnic identities that were shaped by migration to the region over the past 400 years. We connect ethnic identities and patterns of ancestry estimation to resistance to colonial hegemony and discuss the implications of our results for the construction of ethnic identities, now and in the past.

    

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2. On the number of genealogical ancestors tracing to the source groups of an admixed population

   https://doi.org/10.1093/genetics/iyad079  

   Mooney, Jazlyn A. ; Agranat-Tamir, Lily ; Pritchard, Jonathan K. ; Rosenberg, Noah A. ; Novembre, ed., J. ( July 2023 , GENETICS)

   Members of genetically admixed populations possess ancestry from multiple source groups, and studies of human genetic admixture frequently estimate ancestry components corresponding to fractions of individual genomes that trace to specific ancestral populations. However, the same numerical ancestry fraction can represent a wide array of admixture scenarios within an individual’s genealogy. Using a mechanistic model of admixture, we consider admixture genealogically: how many ancestors from the source populations does the admixture represent? We consider African-Americans, for whom continent-level estimates produce a 75–85% value for African ancestry on average and 15–25% for European ancestry. Genetic studies together with key features of African-American demographic history suggest ranges for parameters of a simple three-epoch model. Considering parameter sets compatible with estimates of current ancestry levels, we infer that if all genealogical lines of a random African-American born during 1960–1965 are traced back until they reach members of source populations, the mean over parameter sets of the expected number of genealogical lines terminating with African individuals is 314 (interquartile range 240–376), and the mean of the expected number terminating in Europeans is 51 (interquartile range 32–69). Across discrete generations, the peak number of African genealogical ancestors occurs in birth cohorts from the early 1700s, and the probability exceeds 50% that at least one European ancestor was born more recently than 1835. Our genealogical perspective can contribute to further understanding the admixture processes that underlie admixed populations. For African-Americans, the results provide insight both on how many of the ancestors of a typical African-American might have been forcibly displaced in the Transatlantic Slave Trade and on how many separate European admixture events might exist in a typical African-American genealogy.

    

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3. Historical genomes elucidate European settlement and the African diaspora in Delaware

   https://doi.org/10.1016/j.cub.2023.04.069  

   Fleskes, Raquel E. ; Owsley, Douglas W. ; Bruwelheide, Karin S. ; Barca, Kathryn G. ; Griffith, Daniel R. ; Cabana, Graciela S. ; Schurr, Theodore G. ( June 2023 , Current Biology)

   The 17th-century colonization of North America brought thousands of Europeans to Indigenous lands in the Delaware region, which comprises the eastern boundary of the Chesapeake Bay in what is now the Mid- Atlantic region of the United States.1 The demographic features of these initial colonial migrations are not uni- formly characterized, with Europeans and European-Americans migrating to the Delaware area from other countries and neighboring colonies as single persons or in family units of free persons, indentured servants, or tenant farmers.2 European colonizers also instituted a system of racialized slavery through which they forcibly transported thousands of Africans to the Chesapeake region. Historical information about African- descended individuals in the Delaware region is limited, with a population estimate of less than 500 persons by 1700 CE.3,4 To shed light on the population histories of this period, we analyzed low-coverage genomes of 11 individuals from the Avery’s Rest archaeological site (circa 1675–1725 CE), located in Delaware. Previous osteological and mitochondrial DNA (mtDNA) sequence analyses showed a southern group of eight individ- uals of European maternal descent, buried 15–20 feet from a northern group of three individuals of African maternal descent.5 Autosomal results further illuminate genomic similarities to Northwestern European refer- ence populations or West and West-Central African reference populations, respectively. We also identify three generations of maternal kin of European ancestry and a paternal parent-offspring relationship between an adult and child of African ancestry. These findings expand our understanding of the origins and familial relationships in late 17th and early 18th century North America. 

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4. Admixture in Africanized honey bees ( Apis mellifera ) from Panamá to San Diego, California (U.S.A.)

   https://doi.org/10.1002/ece3.8580  

   Zárate, Daniela ; Lima, Thiago G. ; Poole, Jude D. ; Calfee, Erin ; Burton, Ronald S. ; Kohn, Joshua R. ( February 2022 , Ecology and Evolution)

   The Africanized honey bee (AHB) is a New World amalgamation of several subspecies of the western honey bee (Apis mellifera), a diverse taxon historically grouped into four major biogeographic lineages: A (African), M (Western European), C (Eastern European), and O (Middle Eastern). In 1956, accidental release of experimentally bred “Africanized” hybrids from a research apiary in Sao Paulo, Brazil initiated a hybrid species expansion that now extends from northern Argentina to northern California (U.S.A.). Here, we assess nuclear admixture and mitochondrial ancestry in 60 bees from four countries (Panamá; Costa Rica, Mexico; U.S.A) across this expansive range to assess ancestry of AHB several decades following initial introduction and test the prediction that African ancestry decreases with increasing latitude. We find that AHB nuclear genomes from Central America and Mexico have predominately African genomes (76%–89%) with smaller contributions from Western and Eastern European lineages. Similarly, nearly all honey bees from Central America and Mexico possess mitochondrial ancestry from the African lineage with few individuals having European mitochondria. In contrast, AHB from San Diego (CA) shows markedly lower African ancestry (38%) with substantial genomic contributions from all four major honey bee lineages and mitochondrial ancestry from all four clades as well. Genetic diversity measures from all New World populations equal or exceed those of ancestral populations. Interestingly, the feral honey bee population of San Diego emerges as a reservoir of diverse admixture and high genetic diversity, making it a potentially rich source of genetic material for honey bee breeding.

    

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5. Biological diversity in an Islamic archaeological population: A radiogenic strontium isotope and craniometric analysis of affinity in Ottoman Romania

   https://doi.org/10.1002/ajpa.23999  

   Allen, Kathryn_Grow ; Mills, Ryan_D ; Knudson, Kelly_J ; von_Cramon‐Taubadel, Noreen ( January 2020 , American Journal of Physical Anthropology)

   Written accounts, as well as a previous craniometric study, indicate that migrations of non‐Europeans and conversions of Europeans to Islam define Ottoman communities in Early Modern Europe. What is less clear are the roles of migration and admixture in generating intra‐communal variation. This study combines craniometric with strontium isotope data to compare the cranial affinities of locally born and immigrant individuals. We predict that locally born individuals are more likely than non‐locals to show evidence of admixture.

   Radiogenic strontium isotope data for 21 Ottomans were compared against archaeological faunal values. Sixteen individuals with intact crania were also measured and compared against two comparative source populations from Anatolia and Europe. Discriminant function analysis assigned unclassified Ottoans to either comparative group based on typicality probabilities, with potential admixture established via intermediate morphology between the two source populations.

   Strontium isotope values revealed relatively high proportions of non‐locals, consistent with high mobility documented historically. The sexes differed, with more males classifying as “typically Anatolian” than females. Locals and non‐locals also had different cranial affinity patterns, with most classifying either as “typically Anatolian” or “typically European.” Contrary to expectation, none of the locals were identified as intermediate, suggesting admixture rates were relatively low.

   Consistent with historical records, the results revealed high levels of extra‐regional migration, with most individuals identifiable as either typically Anatolian or European. Moreover, locals and non‐locals differed craniometrically, with no signs of admixture between Anatolian migrants and European converts in locals. This suggests intra‐communal divisions were maintained.

    

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