Are African Americans really mostly “Nigerian”?

Last year 23andme’s research team published a major landmark study titled “Genetic Consequences of the Transatlantic Slave Trade in the Americas“. Arguably the largest DNA study to examine African ancestry in the Americas! Covering a wide span of the Afro-Diaspora, incl. also several thousands of African Americans. Highly interesting therefore. The research approach of this study consists of combining genetic data obtained from 23andme customers with Trans-Atlantic Slave Trade patterns. Which is practically the same approach I have been using ever since I started my AncestryDNA survey in 2013. This study by 23andme is even including Cape Verdean samples as a control group! Which is something I have done as well in all my research sofar.1 Since I have recently finished my survey findings based on 23andme results (2018/2019 version) it should be useful to compare notes.

23andme’s 2020 study

My own survey findings based on 23andme and AncestryDNA results

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Table 1 (click to enlarge)

This overview is showing the scaled African breakdown for the combined USA sample group (n=5785) featured in Micheletti et al. (2020). As well as for my own African American survey group (n=200). Despite smaller sample size actually very similar outcomes. Providing mutual corroboration. As can be seen “Nigerian” was clearly the most significant region. Going by group averages around 35%. Usually “Nigerian” is appearing as primary African category (162/200=81% in my survey). But even so “Nigerian” is still far from being predominant (>50%). Especially “Ghanaian, Liberian & Sierra Leonean” is also showing up as a substantial component. Furthermore regional scores indicative of Senegambian and Central African DNA are still considerable and nearly at 10%, on average. Making for an overall varied and rather balanced African breakdown. Do notice as well that around 20% of the African breakdown is falling in one of the “Broadly” categories!

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In this blogpost I will compare my own research findings (based on regional admixture) with 23andme’s study from 2020. In fact much of the data contained in 23andme’s study (based on the 2018 version of Ancestry Composition) is consistent with my own. As demonstrated above in Table 1. Which features the African breakdown for African Americans on 23andme (scaled to 100%).2 Despite smaller sample size on my part actually very similar outcomes. Providing mutual corroboration. The study’s main findings of lower Senegambian and higher Nigerian ancestry than expected for African Americans are in line with what I had already established in my 2015 survey. Based on AncestryDNA test results for 350 African Americans. As well as more recently in my 23andme survey. See also:

Within the remaining part of this blog post I will discuss the following:

  1. Why do so many African Americans have Nigerian ancestry?
    • Ancestral implications of “Nigerian” go beyond modern-day borders
    • Domestic Slave Trade from mostly Virginia spreading Bight of Biafra lineage
    • Lower Senegambian than expected because of less reproduction?
    • Substructure according to state origins
  2. African breakdown for other parts of the Afro-Diaspora 
    • Mostly in agreement with historical expectations
    • Overlap & differences with my own survey findings
    • Regional diversity and substructure
    • Confirmation of Upper Guinean Founding Effect?
  3. Discordances & limitations of 23andme’s study
    • Afro-descended samples taken from migrants underrepresent wider variation in countries of origin
    • Central African IBD disproportionately high when contrasted with regional admixture from Central Africa 
    • Sex-biased admixture: multiple & context-dependent historical narratives! 
  4. Exciting future prospects:  personalized 23andme results featuring African IBD specified according to ethnic groups Continue reading

23andme’s African breakdown put to the test: Afro Diaspora edition!

In the last couple of years 23andme has implemented several updates. Often beneficial for Tracing African Roots! Starting with the introduction of a new African regional framework in 2018. Finally providing a meaningful breakdown of West & Central African ancestry! Soon afterwards I started a survey of 23andme results among Africans as well as African Americans and other Afro-descended nationalities.1 Similar to my previous Ancestry surveys my main research goal has always been to establish how much these results on an aggregated group level can already (despite limitations of sample size and other shortcomings) be correlated with whatever is known about the documented regional African roots for each nationality. As well as to improve correct interpretation of personal results.

Two years ago in February 2019 I published the first part of my examination of 23andme’s African breakdown. Which was based on my surveyfindings for 173 African 23andme testers from 31 countries (see this blog post). My 23andme survey has been ongoing till 23andme’s update in October 2019.2 Because of other projects I have not been able to process my entire data-set earlier. But in this blog post I will at last present my main 23andme survey findings based on 889 results from 28 different countries across the Afro-Diaspora! Actually I have already analyzed these results in greater detail (incl. screenshots of individual results) on these pages:

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Figure 1 (click to enlarge)

A small selection of 23andme results from across the Afro-Diaspora.  Most of the outcomes are roughly corresponding with documented African roots  for each of my survey groups. Unrealistic expectations about “100% accuracy” as well as counter-productive obsessing about regional labeling should be avoided. Instead focus on what ever informational value you can obtain despite imperfections. Take notice as well how the additional Recent Ancestor Locations are on point!

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To summarize: I do indeed believe that 23andme’s African breakdown has passed the test! Although obviously there are several shortcomings to take into account. Based on both my African and Afro-Diasporan surveyfindings I find it quite impressive though that 23andme is often able to describe a person’s African origins in a meaningful regional framework. Which will usually quite closely correspond with either known genealogy or historical plausibility. The additional non-African scores and Recent Ancestral Locations actually reinforcing the robustness of 23andme’s predictions. In the remaining part of this blog post I will discuss the following:

  1. African Breakdown
    • Main outcomes
      • Upper Guinean Founding Effect for Hispanic Americans
      • Virginia’s African roots most impactful on African American overall genepool?
      • Meaningful differentiation between Anglo-Caribbeans, Dutch Caribbeans and Garifuna
    • Frequency of primary African regions
    • Historical plausibility
  2. Substructure
    • African Americans, Brazilians, Cape Verdeans, Haitians, Hispanic Americans, West Indians
  3. Continental Breakdown
    • Southeast Asian admixture indicative of Madagascar connection
  4. Recent Ancestor Locations:
    • Pinpointing African lineage
    • Cross-Diaspora connections
  5. Screenshots 
    • Distinctive results across the Diaspora
    • Similar results across the Diaspora
    • Underrepresented parts of the Afro-Diaspora
    • Hispanic results reflecting Upper Guinean Founding Effect
    • Partially Cape Verdean results

Continue reading

“Benin/Togo” also describes DNA from Ghana & Nigeria

I have created a new page featuring the AncestryDNA results for West Africans from the following countries: Liberia, Ivory Coast, Burkina Faso, Ghana, Togo & Benin. I will create a new section for the remaining part of West Africa (Upper Guinea) shortly. The number of results I have collected so far might be minimal but already my survey findings turn out to be quite insightful. I also provide some statistical data, analysis and relevant context. Follow this link to view the page:

In addition I also discuss the implications these findings might have for Afro-Diasporans in an attempt to improve proper interpretation of their West African regional scores, in particular for “Ivory Coast/Ghana” and “Benin/Togo”. One of these implications I will also discuss in greater detail in this blog post:

“Benin/Togo” is also predictive of Ghanaian & Nigerian DNA

The so-called “Benin/Togo” region seems to be quite predictive of Beninese origins (based on two results). However in addition ancestry from eastern Ghana and southern Nigeria might also be described by this region. You will need to perform your own follow-up research in order to find out more specifics.

Map 1 (click to enlarge)

Benin Togo

Source: ancestry.com

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Chart 1 (click to enlarge) 

Stats (GH=22)

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Continue reading

“Ivory Coast/Ghana” also describes Liberian DNA

I have created a new page featuring the AncestryDNA results for West Africans from the following countries: Liberia, Ivory Coast, Burkina Faso, Ghana, Togo & Benin. I will create a new section for the remaining part of West Africa (Upper Guinea) shortly. The number of results I have collected so far might be minimal but already my survey findings turn out to be quite insightful. I also provide some statistical data, analysis and relevant context. Follow this link to view the page:

In addition I also discuss the implications these findings might have for Afro-Diasporans in an attempt to improve proper interpretation of their West African regional scores, in particular for “Ivory Coast/Ghana” and “Benin/Togo”. One of these implications I will also discuss in greater detail in this blog post:

“Ivory Coast/Ghana” is also predictive of Liberian & Sierra Leonean DNA

The socalled “Ivory Coast/Ghana” region is indeed quite predictive of both Ghanaian and Ivorian origins. However in addition ancestry from Liberia and to a lesser degree (southern) Sierra Leone might also be described by this region. You will need to perform your own follow-up research in order to find out more specifics.

Map 1 (click to enlarge)

IvcGhana region

Source: ancestry.com. (text in red added by myself)

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Chart 1 (click to enlarge) 

Stats (GH=22)

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Continue reading

Guyanese Slave Census of 1819 , less specified but still representative?

Berbice (Guyana) Slave Census of 1819

SUMMARY

Number of slaves 23,881
Creole (i.e. born in the Americas) 10,954 (46% of total)
African 12,867 (54% of total)
African specified ethnically/regionally 1,198 (5% of total)

BREAKDOWN OF AFRICAN BORN SLAVES

Kongo (Congo) 212 – 18% of African specified
Coromantee (Ghana) 139 – 12% of African specified
Popo (Benin/Togo) 113 – 9% of African specified
Source

Origins of African-born slaves Berbice 1819 Continue reading