Genetic Consequences of the Transatlantic Slave Trade in the Americas

Abstract

According to historical records of transatlantic slavery, traders forcibly deported an estimated 12.5 million people from ports along the Atlantic coastline of Africa between the 16th and 19th centuries, with global impacts reaching to the present day, more than a century and a half after slavery’s abolition. Such records have fueled a broad understanding of the forced migration from Africa to the Americas yet remain underexplored in concert with genetic data. Here, we analyzed genotype array data from 50,281 research participants, which—combined with historical shipping documents—illustrate that the current genetic landscape of the Americas is largely concordant with expectations derived from documentation of slave voyages. For instance, genetic connections between people in slave trading regions of Africa and disembarkation regions of the Americas generally mirror the proportion of individuals forcibly moved between those regions. While some discordances can be explained by additional records of deportations within the Americas, other discordances yield insights into variable survival rates and timing of arrival of enslaved people from specific regions of Africa. Furthermore, the greater contribution of African women to the gene pool compared to African men varies across the Americas, consistent with literature documenting regional differences in slavery practices. This investigation of the transatlantic slave trade, which is broad in scope in terms of both datasets and analyses, establishes genetic links between individuals in the Americas and populations across Atlantic Africa, yielding a more comprehensive understanding of the African roots of peoples of the Americas.

Genetic landscape of Gullah African Americans

“…Within Africans, red indicates a West African (aka African Rice Coast) ancestry (highest in the Mandenka of Senegal and Sierra Leone ethnic groups), orange a Central and South African ancestry (highest in the San of Namibia and Mbuti of Democratic Republic of the Congo), yellow an East African ancestry (highest in Maasai and Luhya of Kenya), and green a West-Central African ancestry (aka Bight of Benin) ancestry (highest in the Yoruba of Nigeria) analyses showed that, despite the highly variable levels of European and West African ancestry in all African American groups, the Gullah had a lower average level of European admixture than JHS African Americans (Figure 2). The lower European contribution in the Gullah corroborates known differences in ancestry proportions among African Americans in different U.S. states (Baharian et al, 2016;Bryc et al, 2015;Dai et al, 2020;Mathias et al, 2016;Micheletti et al, 2020;Patin et al, 2017), and confirms that subtle differences in African American population structure can exist at finer regional levels.…”

Recent shifts in the genomic ancestry of Mexican Americans may alter the genetic architecture of biomedical traits

“…Demographic forces such as population bottlenecks, expansions, and migration as well as adaptation to novel environments resulted in observable differences in continental patterns of genetic variation ( Nelson et al, 2008 ; Abecasis et al, 2012 ; Auton et al, 2015 ). These differing patterns were shaped by many historical events of migration which included the founding of the Americas by Amerindigenous populations, the colonization by Europeans, and the African slave trade ( Gravel et al, 2013 ; Homburger et al, 2015 ; Moreno-Estrada et al, 2014 ; Moreno-Estrada et al, 2013 ; Reich et al, 2012 ; Bryc et al, 2015 ; Conomos et al, 2016 ; Han et al, 2017 ; Baharian et al, 2016 ; Jordan et al, 2019 ; Micheletti et al, 2020 ). However additional complexities surrounding these events remain highly understudied.…”

Impact of obstructive sleep apnoea on cardiometabolic health in an ageing population in rural South Africa: Building the case for the treatment of sleep disorders in deprived settings

“…(Egan, Knutson, Pereira, & von Schantz, 2017; Whitesell, Obi, Tamanna, & Sumner, 2018). However, significant differences in genetic (including admixture), environmental and socio-economic circumstances (Micheletti et al, 2020), precludes extrapolating those findings to the situation of Africans living in Africa. Sub-Saharan Africa, and particularly South Africa, is experiencing a profound health transition, characterized by the emergence of non-communicable diseases (NCDs) and the ageing of the population in both rural and urban areas (Mayosi et al, 2009).…”