Gullah Genetics

I have published another new page within the 23andme section of my blog. It features my survey findings based on 100 23andme results as well as 68 AncestryDNA results for African Americans with deep roots from South Carolina. Incl. several Gullah persons! Most of my findings are in agreement with previous published studies on African American genetics. In line with expectations Rice Coast related DNA seems to be more elevated indeed among South Carolinians.¹ As indicated firstmost by a high frequency of primary “Ghanaian, Liberian & Sierra Leonean” scores on 23andme. As well as prominent “Mali” scores on Ancestry. But in fact also Central African lineage and strictly Senegambian²ancestry appear to be more pronounced in South Carolina than elsewhere in the USA. To be sure Nigerian (related) ancestry is very common in South Carolina too but intriguingly it seems to be relatively subdued among Gullah persons.

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Table 1 (click to enlarge)

This overview is exploring regional substructure between various parts of South Carolina. Obviously only preliminary due to minimal sample size. However already a very insightful constrast between coastal and inland areas is surfacing. The Lowcountry and Pee Dee clearly having relatively elevated group averages for “Senegambian & Guinean” and especially “Ghanaian, Liberian and Sierra Leonean”. While “Nigerian” scores are much more prominent in Upstate and Midlands. Intriguingly the substantial Central African level showing up in coastal areas is also maintained into Midlands.

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My analysis is also zooming into coastal areas and contrasting with inland areas within South Carolina. And this kind of granularity might be a first when compared with other research projects (along with the inclusion of Southeast Asian admixture statistics). Atleast as far as I know and also when dealing with regional admixture within Africa as well (otherwise see Parra et al. (2001) for a truly pioneering study). Such a comparison is particularly insightful when wanting to grasp the localized formation of the Gullah people in the Lowcountry and adjacent Pee Dee area! In order to avoid any assumptions being made on my part I will not use Gullah as a synonym for people from the Lowcountry and/or Pee Dee.³ Although of course this is the main area where they are located. Follow the link below for fully detailed analysis, references and screenshots (incl. also AncestryDNA results):

• 100 South Carolina 23andme results

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Genetic Landscape of Gullah African Americans (Zimmerman et al., 2020)

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“Relative to southeastern non-Gullah African Americans, the Gullah exhibit higher mean African ancestry, lower European admixture, a similarly small Native American contribution” […]

“Despite a slightly higher relatedness to Sierra Leone, our data demonstrate that the Gullah are genetically related to many West African populations.” 

“This study confirms that subtle differences in African American population structure exist at finer regional levels. Such observations can help to […] guide the interpretation of genetic data used by African Americans seeking to explore ancestral identities.” (Zimmerman et al., 2020)

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• Genetic Landscape of Gullah African Americans (Zimmerman et al., 2020)

In this blogpost I will compare my own research findings with a very interesting recent study on Gullah genetics. This paper, linked above, is currently still in preprint. But it is consistent with several of my own research outcomes. Especially in regards to the quotes above. Impressively the study is based on the autosomal DNA results of 883 unrelated Gullah African Americans! A much larger sample size than I was able to use therefore.

However due to differences in methodology regrettably its potential for breakthrough insights is not fully realized. Resulting in less regionally detailed outcomes than I was able to obtain with my surveys based on 23andme and Ancestry results. To their credit the authors of the study largely succeed in sketching an appropriate historical framework for properly contextualizing their research outcomes. But at times essential details are still lacking while some of the information given appears to be outdated or not well referenced. Within the remaining part of this current blog post I will discuss the following:

1. Summary of my own survey findings based on 23andme and AncestryDNA results
2. Review of Genetic Landscape of Gullah African Americans (Zimmerman et al.; 2020)
3. African DNA matching patterns, beneficial for creating your own narrative about your personal African roots!
4. Screenshots of 23andme & Ancestry results for African Americans from South Carolina

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23andme & AncestryDNA results for 2 confirmed Gullah persons

(click to enlarge)

Dr. Henry Louis Gates Jr, Pay Attention 😉 2 (nearly) 100% African results. I have actually seen several similar results because unlike persistent reports to the contrary such results are no unicorns! In fact the interval of 90%-100% African admixture was the most frequent one (41%) during my 23andme survey among African Americans from South Carolina.

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1) My Survey Findings

Of course my own 23andme survey may have several limitations. The group averages I have calculated for my survey-(sub)groups are neither absolute or conclusive but rather to be seen as indicative. One main aspect to take to heart is that  there will always be individual variation around the mean! My current surveyfindings are naturally still somewhat preliminary, due to minimal sample size for the areas within South Carolina. Still the overall sample size of n=100 should be sufficiently robust to pick up on the main tendencies.

I find it very remarkable how much can already be supported by additional reasoning. Resulting in plausible outcomes when looking at the relevant context and the relevant statistics! Unlike commonly assumed you do not need to sample entire populations to obtain informational value with wider implications. Naturally greater sample size does (usually) help matters. However I find it reassuring that also in my previous survey efforts published studies based on larger sample size have usually vindicated or confirmed my own findings.  While due to free format on my blog I am often able to provide greater detail and more appropriate context.⁴

Continental breakdown

Table 1.1 (click to enlarge) 

Similar to other African Americans also people from South Carolina tend to be clearly of predominant African descent combined with minor other ancestral components. Despite inner-state variation it is however quite likely that people from South Carolina might have the highest degree of African DNA, nation wide. At least on average. Tellingly also the most frequent African admixture interval being 90%-100%, instead of 80%-90%.  See this screenshot for an overview of my previous 23andme survey findings (n=200). As well as this one specifying the group average for 20 results from South Carolina (2018 version).

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Table 1.2 (click to enlarge) 

The within-South Carolina origins of my survey participants are not based on a 4 grandparents criterium per se. But often this was indeed confirmed by their profile details on 23andme. Obviously minimal sample size for the most part. But still insightful variation on display. Take notice especially of the highest subgroup averages which have been highlighted in red. As expected the highest African group average is found in the Lowcountry. With the interior areas of Upstate and Midlands actually more so conforming with national group averages. And Pee Dee being somewhat intermediate, although tending more so towards Lowcountry.

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In Table 1.2 above I am exploring if there is any differentiation based on regional origins within South Carolina. The results are more preliminary than shown in Table 1.1. Because the sample size for the 4 main regions within South Carolina is of course minimal. And obviously these regional divisions are only meant to be approximate. As I am aware various definitions may exist. Also naturally I did not have complete knowledge about the family origins of all of my survey participants. Although often I was actually able to confirm the county birthplaces of all 4 grandparents. Merely meant as an exploratory excercise therefore. But still already quite insightful for indicating that as expected African ancestry is most elevated in the Lowcountry. While the interior areas of Upland and Midlands are actually conforming with nationwide group averages! See maps below for regional definitions:

• Gullah/Geechee Corridor map
• Map of 4 main regions with South Carolina (source)
• Rice Coast Map (taken from Gullah Roots)

Dr. Henry Louis Gates Jr, Pay Attention!

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“The average African-American is 24 percent European.“, (Dr. Henry Louis Gates Jr., 2019)

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Chart 1.1 (click to enlarge) 

This chart is showing the full extent of African ancestry among my South Carolina survey participants. The most frequent African admixture interval is 90%-100%.  Very useful to compare with my overall African American surveyfindings (n=200, see this chart). As actually for African Americans as a whole it is instead the 80%-90% admixture interval which seems to be most frequent. Notwithstanding wider variation of course.

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African breakdown

Table 1.3 (click to enlarge)

“Ghanaian, Liberian & Sierra Leonean” is slightly more prominent than “Nigerian” for my South Carolina survey group. Very telling outcome because for African Americans as a whole it is actually the other way around! See this overview for 100 African American 23andme results (2020 version). Also noteworthy that “Angolan & Congolese” showed up as primary region a few times (see ranked #1).  Aside from the group averages do take notice too of the complete range (min-max) for greater insight!

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Comparing with other US states

Table 1.4 (click to enlarge)

This table is combining the data from my South Carolina survey with the findings from my additional African American survey which did not include any South Carolina results. The data has been sorted on lowest to highest score for “Nigerian”. The highest group averages for each region have been encircled in red. Obviously several limitations might apply, however the ranking order is mostly in agreement with historical plausibility. The greatest contrast existing between South Carolina and Virginia. Compare also with my previous findings based on the 2018 version of 23andme.

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Table 1.5 (click to enlarge)

This overview shows how many times each African region was reported as number 1 region with the highest amount in the African breakdown. Measured as a relative frequency. The data should be interpreted carefully because hypothetically if a region is consistently mentioned in second place it will not be shown in this overview. Main takeaway being that only South Carolina has “Ghanaian, Liberian & Sierra Leonean” as most frequent primary region. However a declining gradient seems to be at work whereby Georgia and Florida as well as Louisiana are shown to have similar regional patterns as South Carolina.

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Substructure according to within-state origins

Table 1.6 (click to enlarge) 

This overview is exploring regional substructure between various parts of South Carolina. Obviously only preliminary due to minimal sample size. However already a very insightful constrast between coastal and inland areas is surfacing. The Lowcountry and Pee Dee clearly  having relatively elevated group averages for “Senegambian & Guinean” and especially “Ghanaian, Liberian and Sierra Leonean”. While “Nigerian” scores are much more prominent in Upstate and Midlands. Intriguingly the substantial Central African level showing up in coastal areas is also maintained into Midlands.

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Table 1.7 (click to enlarge) 

This overview shows how many times each African region was reported as number 1 region with the highest amount in the African breakdown. Measured as a relative frequency. The data should be interpreted carefully because hypothetically if a region is consistently mentioned in second place it will not be shown in this overview. Main takeaway being that only the Lowcountry and Pee Dee have “Ghanaian, Liberian & Sierra Leonean” as most frequent primary region. The inland areas of Midlands and especially Upstate showing a greater prevalence of “Nigerian” scores. Probably indicative of a greater reliance on Domestic Slave Trade, originating mostly from Virginia.

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Table 1.8 (click to enlarge) 

2013-2018 version. My final AncestryDNA surveyfindings (2013-2018) are clearly demonstrating how results from South Carolina can be distinguished from nationwide African American results. Reflected among other things in a lower “Nigeria” group average. But notice especially the 24% Upper Guinean share and 34% Central African share for my Gullah survey group. These macro-regional components are more prominent when compared with African Americans as a whole. But in fact also more pronounced when compared with my other South Carolina survey participants.

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2) “Genetic Landscape of Gullah African Americans”

Link to study:

• Genetic Landscape of Gullah African Americans (Zimmerman et al., 2020)

Chart 2.1 (click to enlarge)

This chart is displaying how Rice Coast related DNA is showing a “slightly higher relatedness” among Gullah persons. When comparing with a separate set of 1,322 African Americans from Jackson, Mississippi (JHS AA).

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Main Outcomes

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“[…], 883 unrelated Gullah African Americans, 381 unrelated Sierra Leone Africans, 7 Mixtecs, and 1,322 unrelated JHS African Americans  [from Jackson, Mississippi] were retained for analyses.”

“Despite a slightly higher relatedness to Sierra Leone, our data demonstrate that the Gullah are genetically related to many West African populations.”

“The results of this analysis support the multi-African ancestry and reduced European admixture of the Gullah compared to other U.S. African American populations. These results are consistent with historical data, which indicate that the Gullah are a mixture of numerous people from different genetic, ethnic, and linguistic currents who formed their own culture and language.“

“[…] with the average African contribution to the Gullah African Americans being 90.7% compared with 82.2% in JHS African Americans (Table 1). Among studies of African ancestry in different U.S. regions, the high African ancestry proportion seen in the Gullah was nearly matched in a U.S. cohort of African Americans sampled within rural Southeast U.S. (89% in Florida and 88% in South Carolina) (3). Thus, the Gullah show the highest average African ancestry proportion of any U.S. African American group studied to date.”

“A slightly tighter bottleneck in the Gullah 13 generations ago suggests a largely shared demographic history with non-Gullah African Americans“

“Although the subtle genetic differences relative to Southeastern non-Gullah African Americans support somewhat different demographic histories, these results also reveal largely shared common ancestries. As such, our data shows that the Gullah are not a genetically distinct group per se, but rather a culturally distinct group of African Americans with subtle variation in its genetic structure.” (Zimmerman et al., 2020)

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This recent study offers several valuable insights into Gullah genetics! Usually also in agreement with my own findings shown in the previous section. In particular a higher than average degree of African ancestry among the Gullah (91.5% for the Lowcountry, see Table 1). As well as confirming that in line with historical documentation the Gullah have varied West African roots (as well as from Central Africa actually!). But still Rice Coast related DNA does stand out somewhat. In particular when comparing with African Americans from elsewhere. In this study the comparison being made is between 883 Gullah African Americans with “parents born and raised in the Sea Islands region of South Carolina“. As well as 1,322 African Americans from Jackson, Mississippi. Laying a promising groundwork for this line of research.

As shown previously in my survey findings I was also able to compare with a sample group from Mississippi and five other states (see Table 1.4). As well as actually making a comparison between coastal and inland areas within South Carolina (see Table 1.6). Based on my own smaller-sized but more granular dataset I am inclined to think that the degree of genetic distinction among Gullah people might be greater than found in this study. As epitomized especially by the frequency of primary “Ghanaian, Liberian & Sierra Leonean'” scores (see Table 1.5 & Table 1.7).⁵ Although I certainly agree that there is a great deal of overlap and shared ancestry as well with African Americans from elsewhere.

A fascinating section of this study deals with the genetic effects of founder events and population bottlenecks. Intriguingly the authors mention “a bottleneck event 13 generations ago for both groups, an estimate consistent with the turn of the 18th century.” I suppose this would be around the time Domestic Slave Trade from mostly Virginia underwent an acceleration due to the Cotton Boom and the Louisiana Purchase. This probably requires further research/interpretation. But quite likely this finding could be enhanced and given greater meaning when focusing on geographical patterns of IBD matching among African Americans (incl. Gullah). As well as looking into what kind of genetic clusters they form. Akin to the Genetic Community feature on Ancestry.

Inadequate African reference panel

Chart 2.2 (click to enlarge)

This overview is taken from the study’s supplement. It shows which African reference populations are being used to determine regional admixture for the Gullah study participants. Notice that historically relevant Bantu speaking populations from Central Africa are missing. Only marginal so-called hunter-gatherer samples (Biaka & Mbuti) are representing Middle Africa. See this overview for a more detailed listing of the samples being utilized by this study.

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As shown above the African dataset being used by this study is quite limited in scope. West Africa being represented by the usual Yoruba and Mandenka samples. Something which has been almost a default feature in DNA studies since at least 2009 (see this page).  A somewhat outdated approach therefore. Especially given that much more ample academic databases are now available. Containing a much greater variety of African samples. Although the addition of Sierra Leonean samples certainly is very meaningful.⁶ Instead of Yoruba samples from Nigeria Igbo samples would probably be more appropriate for the African American context. Given that Bight of Biafra origins will generally be prevailing over Bight of Benin ones (see this overview). Also Ghanaian samples might have been useful. In a previous study involving Gullah genetics (male haplogroups) their absence was also an issue. See my review:

• Y Chromosome Lineages in Men of West African Descent (Torres et al., 2012)

A much more crucial shortcoming however is the absence of historically relevant Bantu samples from Central Africa. As shown in chart 2.2 the only samples representing Middle/Central Africa are taken from so-called hunter-gatherer populations (Biaka & Mbuti). These people are known to be genetically very distinct which is why they are often featured in DNA testing. But they are also hardly if at all contributing to the African DNA of African Americans and other Afro-descendants! This can also be verified from chart 2.1 in which the orange component (indicative of “Central and South African ancestry”) is practically absent. A much more obvious choice would have been to compare with Central African Bantu samples instead. For example Bakongo samples from DRC Congo which are also used by 23andme and Ancestry. Because this enables a reasonable indication of Central African DNA  by both DNA testing companies. Central African ancestry of course being quite substantial for South Carolinians. As reflected in my survey findings as well as testified by plentiful historical and cultural evidence. See also:

• African breakdown on 23andme
• African breakdown on Ancestry
• Rituals of Resistance: African Atlantic Religion in Kongo and the Lowcountry South in the Era of Slavery (J. Young, 2007)

Historical context

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“This striking linguistic resemblance, coupled with multiple cultural links (e.g., rice growing techniques, quilts, songs, stories), has led to a commonly held folk history that the Gullah are descendants of enslaved Africans from the African Rice Coast, the traditional rice-growing region stretching south from Senegal to Sierra Leone and Liberia.”

“The recorded legal slave trade into Charleston, South Carolina, documents approximately 39% of enslaved Africans as originating from West Central Africa (present day Angola, Congo, and part of Gabon), 20% from Senegambia (present day Senegal and Gambia), 17% from the Windward Coast (present day Ivory Coast and Liberia), 13% from the Gold Coast (present day Ghana), 6% from Sierra Leone (present day Sierra Leone and Guinea), and 5% from the Bights of Benin and Biafra (Togo, Benin, Nigeria, Cameroon, and part of Gabon” (Zimmerman et al., 2020)

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Whenever I read genetic studies I always pay close attention to how the authors attempt to contextualize or explain their main research findings. As I find that historical aspects often tend to be oversimplified or even misrepresented. Given that the authors of genetic studies are usually mathematically trained naturally they tend to be focused rather on the technical aspects of whatever it is they are researching. However genetics is embedded in the social sciences as well. Especially the history of population migrations. Not meant to be exhaustive but read these pages for more background and references on the Gullah:

• Gullah/Geechee History and Culture (Library of Congress)
• Comparing the Gullah language with other English-based Creoles (2015)
• Ethnic Origins of South Carolina Runaway Slaves (2015)
• Gullah Roots (2020; documentary about a homecoming experience in Sierra Leone, a sequel to SCETV’s 1990 documentary Family Across the Sea)

I actually find that this study does a good job at describing an appropriate historical framework that fits their research outcomes quite well. Possibly because the authors received external advice from Queen Quet, leader of the Gullah/Geechee Nation. As she is mentioned as one of the contributors. For example I was pleasantly surprised to see various linguistic theories about the Gullah language and its origins being mentioned. Also the minor but still detectable Native American heritage of the Gullah was well supported by also referring to the great historical source of Runaway Slave advertisements. A topic I blogged about already in 2015. But at times essential details are still lacking while some of the information given appears to be outdated or not well referenced. Given that this paper is still in pre-print naturally this is just meant as constructive criticism.

Generally speaking I was missing any discussion of the possible impact of Domestic Slave Trade as well as Illegal Slave Trade after 1808 (often involving Sierra Leone!). For South Carolina as a whole these incoming flows of people certainly seem to be relevant. Aside from the more widely known founding effect of Intra-American Slave Trade. The early connection with in particular Barbados is certainly also significant (see this page). However as discussed in my own surveyfindings I greatly suspect that especially Domestic Slave Trade might be a major factor accounting for the differentiation I found between inland and coastal areas within South Carolina. As well as actually between South Carolina and other states. Reflected especially in the variation of “Nigerian” scores but possibly also in the levels of European and even Southeast Asian admixture. Perhaps ultimately introduced mostly by way of Virginia.⁷

More specifically I greatly suspect that the study uses outdated estimates of Trans Atlantic Slave Trade into South Carolina. The quote shown above is quite likely based on the classic “The Atlantic Slave Trade: A Census” written by Philip D. Curtin in already 1969! This highly influential book from fifty years ago is still a very valuable source of information. But for many years already actually the Trans-Atlantic Slave Voyages Database has become a standard reference among researchers. Because it is simply the most comprehensive and up-to-date resource available when wanting to look into Trans-Atlantic Slave Trade patterns. The estimated share of slave trade originating from Sierra Leone right now being around 16% (35,042/210,476) instead of 6%. See also:

• Table 45 from “The Atlantic Slave Trade: A Census” (Curtin, 1969)
• Trans Atlantic Slave Trade Estimates for South Carolina/Georgia (www.slavevoyages.org)

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“The Mende (31%), who live mostly in the Southeast and the Kono District, originated in a region near western Sudan, but migrated from the inland to the coast between the 2nd and 16th centuries to trade woven cloths for salt” (Zimmerman et al., 2020)

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In regards to the quote above there is still quite some uncertainty about the exact origins of the Mende. As it has been a topic of debate for several decades already. However their spectacular migration into presentday Sierra Leone from neighbouring Liberia during the 1500’s has been rather well documented by Portuguese and actually also Cape Verde-born writers of that time (see this page). Given that the Mende people speak a southwestern Mande language and other cultural practices I would think therefore that their West African origins are well established.  Atleast for the last thousand years, but probably also beyond that. As has in fact been confirmed by several genetic studies! So in order to avoid any confusion this should also be the main departing point. Frankly I have never read anything about documented or even orally transmitted western Sudanese origins for the Mende (unless a reference is being made to the western Sahel instead?) For quick reference:

• The “Mende Problem” (D. Dwyer, 2005)
• “Ivory Coast/Ghana” most notable for Sierra Leoneans (scroll down to section 3)

3) African DNA Matching Patterns

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“as a result of the Trans-Atlantic slave trade, African Americans were robbed of their African heritage and left with limited information about ancestors and homelands. The longing for identity and belonging leads many African Americans to actively draw together and evaluate various sources of genealogical information (historical, social and genetic) in order to weave together ancestry narratives.” (Zimmerman et al., 2020)

“Similar to the famous Gullah craft of sweetgrass basket weaving it seems that the Gullah themselves have richly intertwined origins hailing from several parts of West & Central Africa. The same goes of course for almost all Afro-diasporic groups who are also mixed in between many African regions & ethnic groups. Ancestral locations within western Africa will generally speaking be the same ones but the relative share of specific ethnic groups in the overall ancestral mix might vary.” (Fonte Felipe, 2015)

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DNA studies such as Zimmerman et al. (2020) as well as my own surveyfindings can serve as helpful tools in your own personal quest to Trace African Roots. Although as always you do need to keep in mind inherent limitations. For those not accustomed to reading DNA studies they might seem daunting at first. Still I think that if you wish to see your personal DNA test results being placed in a wider context DNA studies can be very valuable. This is besides any general interest of course. See link below for some tips on how to “read” DNA studies.

• Tips from a layman

I firmly believe that given correct interpretation regional admixture estimates can be very useful as a stepping stone for follow-up research. And just to get a general idea of where most of your African ancestors hailed from. All according to the latest state of knowledge. Which naturally may be improved upon across time. I find it important to stay positive and focus on what ever informational value you can obtain despite imperfections. Instead of taking an dismissive stance right from the start. Preferring to see the glass as half full rather than half empty 😉 You do need to make an effort yourself and stay engaged to gain more insight though!

In particular your follow-up research may include a focus on your African DNA matching patterns and how your African DNA matches may validate or correlate with your regional admixture scores. For example if you find around 10 African matches and 3 of them appear to be Sierra Leonean then this solidifies and also potentially specifies any major “Ghanaian, Liberian & Sierra Leonean” score you might have obtained on 23andme.

To be kept in mind though is that the “Ghanaian, Liberian & Sierra Leonean” category can have various ancestral implications. Also covering Mali and surrounding countries in fact (see this map and also this page for the 23andme results of a few (mixed) Malian persons). But given the South Carolina context a main Sierra Leone connection or better yet a proxy of Rice Coast lineage should be very likely. Looking into associated DNA matches will usually provide greater clarification. See also:

• Relative proportions of Trans Atlantic Slave Trade from Sierra Leone, Liberia, Ivory Coast & Ghana
• African DNA matches reported by Ancestry for 50 African Americans (incl. some persons from South Carolina) (under preparation)

Table 3.1 (click to enlarge)

This is the first page of an African DNA Matches Report I made for a person with confirmed Gullah background. See this screenshot for his 100% African results, including a primary “Mali” score! Showcasing the potential of how your African DNA matching patterns may enable further ethnic specification of your Rice Coast lineage. As actually this person has DNA matches from several countries across Upper Guinea, stretching into Liberia! And aside that also from Ghana and Nigeria. Intriguingly the number of Nigerian matches being quite subdued when compared with the African DNA matches of African Americans from elsewhere.

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4) Screenshots

Just a small selection. Go to the main page for many more screenshots, including several profiles with 100% African admixture. As well as outliers for each African region, Southeast Asian as well as Native American admixture.

• 100 South Carolina 23andme results

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SOUTH CAROLINA (Lowcountry: Jasper)

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2020 version. Regionally quite balanced breakdown but favouring Rice Coast lineage. Notice the 20.3% “Senegambian & Guinean” score!  Also interesting to see Jamaica being specified as recent ancestor location. But this is quite ambivalent as it might signal various ancestral scenario’s based on DNA matching strength! See also my detailed discussion on this page. Generally speaking Jamaicans and African Americans will often show similar results on 23andme. But is is very apparent from this distinctive South Carolina breakdown that African Americans show greater variety and more regionally balanced results. Aside from more elevated “Senegambian & Guinean” scores also often featuring more elevated “”Angolan & Congolese” scores.

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SOUTH CAROLINA (Pee Dee: Williamsburg, 4gp)

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2020 version.  Nearly 100% African profile without any European admixture! After the 2020 update this person’s “Angolan & Congolese” score has  become primary even with 28.2%! See this screenshot for this person’s earlier results. Curiously his Southeast Asian admixture (all of it on the X chromosome) was then described as Native American! Possibly he has both types of admixture but due to 23andme’s homogenizing algorithm it is being fit into just one category.

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SOUTH CAROLINA (Midlands: Richland 4gp)

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2020 version. Primary “Nigerian” scores have been more frequent among my Midland survey participants (7/11) than for either my Lowcountry or Pee Dee subgroup. Possibly a indication of (partial) lineage hailing from Virginia and its main Bight of Biafra connection.  An additional reason for such a scenario seems to be suggested by the relatively high “Southeast Asian” score.  Second-highest score in my survey.  But intriguingly rather high “Angolan & Congolese” scores were also still reported for persons from Midlands.

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SOUTH CAROLINA (Upstate: Laurens, Anderson, Spartanburg)

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2020 version. Highest scaled “Nigerian” score in my survey. Representing more than half of the African breakdown (41.7/80.3=51.9%). Not surprising that it should occur for someone from Upstate. As my 8 survey participants from that area showed the highest “Nigerian” group average overall (44.1%). Also in other aspects being more similar to African Americans nationwide rather than coastal South Carolinians.

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SOUTH CAROLINA (Lowcountry)

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2013-2018 version. On Ancestry primary “Mali” scores often seem to overlap with “Ghanaian, Liberian & Sierra Leonean” scores on 23andme for South Carolinians. In both cases highly suggestive of broader Rice Coast lineage.

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SOUTH CAROLINA (Lowcountry: Beaufort)

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2020 version. I have not done any extensive surveying yet for updated AncestryDNA results among African Americans. However from what I have seen sofar I greatly suspect that both “Mali” and “Cameroon, Congo & Western Bantu” will be more prominent for many people from South Carolina’s coastal areas. When compared with African Americans nationwide but also infact from South Carolina’s inland areas who instead will much mor frequently show primary “Nigeria” scores. Btw notice that this person only has African and Native American admixture!

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SOUTH CAROLINA (Midlands 4gp: York & Chester)

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2020 version. This person is from the interior part of South Carolina. As confirmed also by the genetic communities. Very insightful primary combination of  “Nigeria” as well as “Cameroon, Congo & Western Bantu”. And “Mali” being relatively subdued. Notice also the additional “Early Virginia AA’s” assignment. Combined with the minimal but distinctive “Southeast Asian” score greatly suggestive of  Domestic Slave Trade reaching interior parts of South Carolina. And in fact through extensive familytree research this person was already aware that on almost all of his family lines his pre-1900’s American roots trace back to Virginia.

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SOUTH CAROLINA (Upstate or Midlands?)

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2020 version.  Fascinating results, tending more so towards Lower Guinea (“Nigeria”) and Central Africa. With Upper Guinean DNA being rather subdued.  I have no certainty about this person’s exact background within South Carolina. But his African breakdown is already quite suggestive of the inner-state substructure I have explored between coastal and interior areas of South Carolina. Apparent not only when based on 23andme results but also to be seen through Ancestry results!

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Notes

1) Various important and insightful studies have been published on African American genetics. At times also including South Carolina. One does need to take into account some differences in methodology. Not meant as an exhaustive overview but these are a few recommended papers:

• Ancestral proportions and admixture dynamics in geographically defined African Americans living in South Carolina (Parra et al., 2001)
  • European admixture among Gullah, Lowcountry and Columbia/Midlands samples
  • Distribution of European admixture among Gullah, Lowcountry and Columbia/Midlands samples
  • Haplogroup frequencies (African, European, Native American)
• Characterizing the admixed African ancestry of African Americans (Zakharia et al., 2009)
• The genetic ancestry of African, Latino, and European Americans across the United States (Bryc et al., 2014)
• The Great Migration and African-American genomic diversity (Baharian et al., 2015)
• Genetic Consequences of the Transatlantic Slave Trade in the Americas (Micheletti et al., 2020)
• Genetic Landscape of Gullah African Americans (Zimmerman et al., 2020)

For an exciting new research project on Gullah Genetics see link below:

• Anson Street African burials project (The Gullah Society)

Follow links below for a section of my blog which features DNA studies on African American genetics which I have reviewed in the past.

• Autosomal DNA studies on African Americans
• Haplogroup studies on African Americans
• Are African Americans really mostly “Nigerian”? (review of Micheletti et al., 2020)

Table 2 (click to enlarge) 

Source. Four different sample groups of African Americans (see this slide, for specification) are being compared with 1,449 Gullah persons.Very insightful research outcomes! Echoing my own surveyfindings to a great extent. In particular a higher than average degree of African admixture (91.5%). As well as a higher level of Rice Coast related DNA. As indicated by the red bar for “Far West Africa”.

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It is very useful also to compare my findings (especially Table 1) with previous but sofar unpublished research from possibly already 2012! Amazingly it appears to provide meaningful within-Africa admixture analysis for no less than 1,449 Gullah samples! I actually only have access to a presentation (originally done for the ASHG conference 2012?) which was based on this research. Although the slides mention “Huang et al. in preparation” I am not aware of this research ever having been published in greater detail. Unfortunately I can only provide this link therefore:

• Differential relatedness of African Americans to populations within West Africa (Katarzyna Bryc, Amy L. Williams*, Yiqi Huang*, Nick Patterson, Solomon, 2012)

Although only containing slides which feature their main research outcomes this presentation is actually already very insightful and pioneering. Especially given that it was apparently already done in 2012! Using a macro-regional set-up (see this map) which is very similar to what I have been using in all my surveys actually. Making a distinction between “Far West Africa” (= Upper Guinea, a.k.a. the Rice Coast); West Africa (=Lower Guinea) and “Central Africa“. Also the general outcomes being quite close to my own.

In particular they report an average amount of 91.8% African ancestry for their Gullah samples (see this slide). While my survey subgroup from Lowcountry had 91.5% African (n=25, see Table 1). Also they mention a scaled share of 28.9% “Far West Africa” or “WestWest” (see this slide) Which is clearly most elevated among their Gullah samples when compared with various other groups of African American samples they analyzed as well (see this slide, for specification) In other words like myself they established that Rice Coast related DNA seems to be more elevated among Gullah. Although to be sure they also found solid indications of DNA hailing from other parts of West Africa as well as Central Africa.

Not that surprising perhaps given that the African Reference Panel which is being used for their analysis is quite similar to 23andme’s African breakdown. In fact one of the persons behind this presentation, Katarzyna Bryc, is currently a Senior Scientist, Population Genetics at 23andMe! Highly fascinating and well-founded research therefore. But also somewhat puzzling and regrettable that this research (as far as I know) has never been officially published.

2) The fact that the balance between “Senegambian & Guinean” and  “Ghanaian, Liberian and Sierra Leonean” is clearly tending more so towards the latter category is quite telling when wanting to find out where Upper Guinean (a.k.a. Rice Coast) lineage for South Carolinians gravitates, on average. It might be useful to compare with Cape Verdean 23andme results in this regard. Because the so-called “Senegambian & Guinean” region is clearly serving as a primary signature region for pinpointing Upper Guinean lineage among all my Cape Verdean survey participants. The group average for “Senegambian & Guinean” being 73.1% of their scaled African breakdown for 100 Cape Verdeans. But in addition also “Ghanaian, Liberian and Sierra Leonean” showed up as a minor but still considerable secondary component at around 10%. And it was also consistently appearing for Cape Verdeans (atleast in the 2018/2019 version). Most likely describing an additional part of Upper Guinean lineage for Cape Verdeans. Sierra Leonean ancestry (Temne) is historically speaking quite likely in fact for Cape Verdeans. See also this page:

• 100 Cape Verdean 23andme results

3) In order to avoid any assumptions being made on my part I will not use Gullah as a synonym for people from the Lowcountry and/or Pee Dee. Although of course this is the main area where they are located (see this map). Within my 23andme survey I did not systematically ask my survey participants if they self-identified as Gullah. However in several cases this was indeed confirmed to me. In my previous Ancestry survey (2013-2018) 14 persons self-identified as being of Gullah descent. Fortunately nowadays Gullah culture is increasingly being celebrated, researched etc.. However not too long ago there may also have been social stigma’s being attached to especially the Gullah language. Which is why especially older generations may not always self-identify as Gullah and newer generations may not always be aware of having (partial) Gullah roots. See also:

• The Real Reason Clarence Thomas Rarely Speaks (US News, 2016)

To be kept in mind as well is that African Americans will have their own perspective on ethnic identity and how it may overlap with racial classification. While certain subgroups such as Louisiana Creoles or also South Carolina Gullah, have their own distinctive culture/history and may also choose to identify accordingly. Naturally I fully respect all of this! And obviously beyond the scope of my research no further implications are intended.

Just as a general disclaimer I should also point out the following. I am aware that admixture test results can be a sensitive topic. My research is purely scholarly. But it also stems from my deep fascination with the entire Afro-Diaspora. I highly admire the many achievements of African Americans in not only the cultural field but also in the social and political domain. But I do not condone the misuse of my research for identity politics! And I will also not allow my blog to be used as a platform for any divisive speech or extremists. DNA testing can be very educational and may have many positive effects. However in some cases it may also be abused by narrow-minded people with bad intentions.

• Can DNA Ancestry Testing Make You More Racist/Tribalistic? (Scientific American)

4) “More is better” is a very current belief. Not only in DNA testing but also generally speaking. However this assumption does not always hold true. I would argue that quality of content should come first. Unlike commonly assumed you do not need to sample entire populations to obtain informational value with wider implications. Naturally greater sample size does (usually) help matters. But if you randomly test a given population, and if your sample group is fairly representative of the whole population, you can make meaningful inferences. Naturally methodology and the assumptions being made should be made explicit, but this is common scientific practice. See also:

• Representative Samples: Does Sample Size Really Matter? (SurveyGizmo)

This is an important lesson I learnt while performing my previous AncestryDNA surveys: robust patterns (in line with historical plausibility) might already be discernible from a sample-size of around n=30. Which is actually often considered a general rule of thumb. Adding more results will indeed lead to greater finesse and more detailed statistics but the main outline might then already be established. Even more so when you are aware of any possible sampling bias or substructure and know how to account for it in your analysis.

And in fact officially published studies based on much larger sample size have usually vindicated or confirmed my own findings. While due to free format on my blog I am often able to provide greater detail and more appropriate context. This goes for example for my survey of 350 African American AncestryDNA results which I published in 2015 already. I was able then to independently verify the coherency of my regional ranking patterns for not only my overall African American survey group. But in fact also for my South Carolina survey subgroup! Because at that time Ancestry publicized the summarized Ethnic Estimates for over 250.000 of their American customers! By way of its so-called “Genetic Census of America” I was able therefore to find confirmation by way of Big Data! Other survey findings of mine on both Ancestry and 23andme have also been independently confirmed or I suspect will be confirmed eventually in upcoming academic studies. In particular this goes for my overall Afro-Diasporan findings:

• Ancestry surveys (regional admixture: 2013-2018)
• Ancestry surveys (DNA matches: 2017- ongoing)
• 23andme surveys (2013-ongoing)

5) Of course several limitations need to be taken into account when relying on the frequency of primary African regions as shown in Table 1.5 & Table 1.7. It is essential to realize these findings represent a simplification of more complex patterns. So this frequency of primary regions is only to be used with discretion and in combination with my other findings and any other relevant details! Focusing on the primary regions can indeed put certain things into clearer perspective but as a consequence secondary regions are being left out of consideration. Also to be kept in mind is that 23andme’s West African breakdown is quite restricted. While the “Broadly..” scores also tend to reach high levels. As soon as 23andme introduces new African categories undoubtedly new patterns will arise (although macro-regionally speaking things should still be quite consistent).

6) The African reference panel being used by Zimmerman et al. (2020) is rather limited in scope. Especially the absence of any historically relevant samples from Central Africa is a crucial drawback. But it does contain many samples from Sierra Leone! Which is certainly very useful for the purposes of their study. But actually they also provide additional analysis for their Sierra Leonean samples which I found quite intriguing. As shown in the quotes below.

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“Our results showed that the most populous ethnic groups (Mende and Temne) form relatively different, but overlapping clusters. The Limba clustered among the Temne, which was unexpected given their distinct, unrelated language, and an early analysis of mtDNA genetic diversity purporting that the Limba could be distinguished from the Mende, Temne, and Loko groups (15). The Limba are indigenous to Sierra Leone, and their dialects are largely unrelated to the other languages in the region.”

“The Krio or Creole formed a relatively distinct cluster along PC2. This pattern of population structure was broadly consistent with individual ancestry estimates (Figure 2 and Supporting Figure S4), where the Temne and Mende showed similar ancestry proportions, and the Creole appeared more variable in their African ancestry than other groups (Figure 2 and Supporting Figure S4). The Creole were also slightly more similar to the Yoruba, while other Sierra Leone ethnic groups showed more genetic similarity to the Mandenka”

“The genetic composition of the Creole was intermediate between that of other Sierra Leone ethnic groups and the Yoruba, with ancestral diversity similar to that of the Gullah African Americans. This finding suggested that they were likely the descendants of individuals from various parts of Africa, including Sierra Leone and beyond, as well as African descended individuals with European admixture. This finding is also consistent with their demographic history, which suggests the Creole descended from freed enslaved Africans (25, 28) who mixed with other ethnic groups”

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In my previous AncestryDNA survey (2013-2018) I have actually described a similar form of substructure among Temne, Mende and Krio persons. Albeit based on minimal sample size still greatly indicative. See overview below as well as these links:

• Results from Sierra Leone (scroll down to section 4 and also read footnote 10)
• Krio from Sierra Leone: Afro-Diasporans with a twist?

Table 3 (click to enlarge) 

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7) For a quick reference on the presence of enslaved Virginians in South Carolina already in the mid 1700’s:

“Governor James Glen [of South Carolina] noted in 1754 that intercolonial merchants seized the moment. “As Negroes are sold at higher Prices here than in any part of the King’s Dominions,” he reported, “we have them sent from Barbadoes, the Leeward Islands, Jamaica, Virginia and New York.” (O’Malley, 2014, p.178)

In later decades Domestic Slave Trade from Virginia and possibly also North Carolina probably increased. I suspect mostly heading towards the inland parts of South Carolina. But also affecting the Lowcountry and PeeDee judging from Runaway Slave advertisements. I am not aware yet of more detailed research on the impact of Domestic Slave Trade into South Carolina. Many historians as well as the general public seemingly seem to be focused rather on South Carolina as an exporter of enslaved labourers to other states. In line with the oft repeated narrative of Charleston being the largest slave port of the USA. Even when it is known as well that due to higher mortality rates etc. the circumstances in the Lowcountry were much less “favourable” than in Virginia for creating a self-reproducing population of enslaved people. And it appears that South Carolina only became a “net -exporter” of enslaved labourers after 1820. When official Trans-Atlantic Slave Trade had already ended. As can be seen from this map from the highly informational In Motion website:

Map 1 (click to enlarge) 

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Just to offer a few more references based on Runaway Slave advertisements published in South Carolina newspapers. Especially the last advertisement being quite evocative as it seems to imply that a local South Carolina accent was being distinguished from a Virginia accent. Possibly therefore referring to the Gullah language? See also this blogpost:

• Ethnic Origins of South Carolina Runaway Slaves

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SouthCarolina Gazette (Timothy), March 12 to March 19, 1763.
RUN away about the 20th of January last, a negro man named NED; he is about 30 years old, short and well made, speaks good English, but thick; he is Virginia born, and it is supposed he will make to the Northward. Whoever will deliver him to the warden of the workhouse, or to me at Congarees, shall have ten pounds and all reasonable charges. AUDEON ST. JOH

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Charleston SouthCarolina Gazette and Country Journal, June 10, 1766.
RAN AWAY the 28th May last, a lusty Negro Fellow named JAMES, about 26 Years of Age, born in North Carolina, or Virginia, he squints a little, is about five Feet ten Inches high, had on when he went away a green Jacket, an Osnaburg Shirt, a Pair of brown Negro Cloth Breeches, an under Jacket of Swanskin lined with Check, and an old beaver Hat; his Hair is cut short; he had also an Iron Boot on his right Leg, but as he has taken two Files with him, may perhaps get it off. He is a sensible Fellow, and as I have been informed, can read and write, therefore may endeavour to pass for a free Fellow; it is supposed he will direct his Course for the back Part of North Carolina. Any Person who shall apprehend the said Negro, and deliver him to me, in St. James’s Parish, Santee, or to the Warden of the WorkHouse, in Charlestown, shall receive Ten Pounds Reward, and all reasonable Charges paid, by PETER MOUZON.

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SouthCarolina Gazette (Timothy), April 5, 1770. Supplement.
RUN AWAY from the Subscriber, in JULY last, A Likely, wellmade, black NEGRO FELLOW named TOM, about 5 Feet 6 Inches high; was some Time ago brought from Wilmington in Virginia, to Salisbury in NorthCarolina, thence sent to CharlesTown, there sold by Mr. William Glen to Mr. Francis Rose, and afterwards sold at GeorgeTown,where I bought him: It is likely he may be gone to, or harboured by some evilminded Person, at some of the above Places: I hereby offer a Reward of FIFTY POUNDS to whoever will prove his being so harboured, to be paid on Conviction of the Offender; or TWENTY

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Charleston SouthCarolina and American General Gazette, August 14 to August 21, 1776.
FIFTY POUNDS REWARD.
RUN away from the subscriber in June last, a very likely Negro Fellow named ELIJAH, of a yellow complexion, is Virginia born, and speaks with the accent of that country; he is about five feet ten or eleven inches high, and about 22 or 23 Years of age, by trade a Blacksmith, an excellent workman at that business. He had on when he went away a scarlet camblet waistcoat, buckskin breeches almost new, an osnaburg shirt and a leather jockey cap. It is supposed, as he is an artful sensible fellow, that he will endeavour to pass for a free man, but all persons are hereby forbid to harbour him on any pretence whatsoever, as any person so offending may depend on the severest prosecution. The above reward of Fifty Pounds currency will be given to any person that will apprehend and deliver the said fellow to the subscriber, or to the Warden of the Workhouse in Charlestown, besides all reasonable charges, provided he is taken out of this province. If the said fellow is harboured by any white person a further reward of One Hundred Pounds, and if by a negro of Fifty Pounds, will be paid on conviction of the offender or offenders. PETER LEPOOLE.

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