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):

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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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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

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

ROOTSTECH 25–27 FEBRUARY 2021: Don’t Miss It!

For those who are not aware: ROOTSTECH Connect is the world’s largest family-history technology conference. And this year it will be a completely FREE and VIRTUAL experience! Hundreds of amazing sessions will be available online during and also after RootsTech Connect has ended on February 27th! Many of those sessions will offer precious insight for Africans and Afro-descendants in their quest to Trace African Roots! All it takes to attend is a free online registration. Right now more than 315,000 participants from more than 200 countries and territories worldwide have already registered! For more details:

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I am very honoured, grateful and excited to also be part of this tremendous event! Because I will be giving an presentation as well! I will be demonstrating my scanning and filtering method to zoom into African matches or any other type of lineage you are interested in researching. I originally devised this technique in 2017. And I have been using it ever since to conduct my ongoing African DNA matches surveys. After registering for ROOTSTECH you should be able to find my class listed in the various search menus. But you can also just directly see it by following the link provided above.

If you are having trouble finding your African DNA cousins this can hopefully offer you a great opportunity to systematically look for your African DNA matches! During the event there will be an occasion to ask any questions by way of a chatroom. But of course you can also always reach me here on my blog if anything needs clarification or just to leave a comment. See also:

In the remaining part of this blog post I will show a few slides for a sneak preview 😉 Furthermore I will also provide all materials/links mentioned during my presentation. For those intending to watch my presentation: Thank you for your attention! I will be rooting for you that the ethnic filtering method I have discussed will be beneficial for you as well! 

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Let’s get this cocktail party started! 😉

Continue reading

200 African American 23andme results

I have just published a new page within the 23andme section of my blog. It features my survey findings for 200 African American 23andme results. Various themes/topics are discussed. Especially delving deeper into the African breakdown but also highlighting a remarkably widespread Madagascar Connection for my African American survey group! Follow the link below for fully detailed analysis, references and screenshots:

Of course my 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! Still the sample size of n=200 should be sufficiently robust to pick up on the main tendencies. I have made an extra effort to do justice to the entire African American spectrum across the country. Of course all done on a best-effort basis.

Continental breakdown

Table 1 (click to enlarge) 

Generally speaking most African Americans are clearly of predominant African descent, combined with minor other ancestral components. Almost all of this additional ancestry will usually be European in fact. Often to a minor but still substantial degree. Aside from much more diluted but still distinctive amounts of especially Native American and perhaps more surprisingly also Southeast Asian admixture! See this screenshot for an overview of my previous Ancestry survey findings (n=350). And also this one featuring the complete continental breakdown (n=200). The overall group averages being nearly identical!

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At the same time I have also focused on gathering atleast a minimum number of 20 survey participants each for Louisiana, South Carolina and Virginia. These are 3 key states when considering African American genetics & origins.

Table 2 (click to enlarge)

The state 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. Either way insightful variation according to state origins. Take notice especially of the highest subgroup averages which have been highlighted in red. The African admixture ranges (min. – max.) were as follows: Louisiana (51%-94%); South Carolina (75%-99%) ; Virginia (56%-94%). Compare also with my previous survey findings on Ancestry.

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Chart 1 (click to enlarge)

This chart is showing the full extent of African ancestry among my African American survey participants. The most frequent African admixture interval is 80-90%.  Which is the same as it was during my  previous Ancestry survey (n=350, see this chart).

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Update of 23andme’s African breakdown

After a long delay of any meaningful improvements 23andme has actually implemented several updates in the last two years. Often beneficial for Tracing African Roots! Starting with the introduction of a new African regional framework in 2018. In 2019 new reference samples were added for especially North Africa. While also the potentially very useful Recent Ancestor Locations feature has been greatly expanded. In this year 23andme has decided to upgrade their customized algorithm. Unlike the 2019 update this upgrade is poised to have a considerable impact on 23andme’s African breakdown. 

Not per se in a positive way though. As it seems that 23andme’s algorithm tends to be “over-smoothing”. That is to say it will tend to homogenize people’s DNA in just a few categories.1 As always one needs to refrain from being overly dismissive in order to also capitalize on any positive aspects. From what I have seen sofar this update does seem to be an improvement for many Afro-descendants, at least on balance. Of course I would need to see more updated results for a more substantiated judgement. For more details read:

Figure 1 (click to enlarge)

General trends of changes after 23andme’s update. According to 23andme (see this link).  The decrease in “unassigned” and most of the “broadly” categories is certainly observable. And especially within the European breakdown this will often be an improvement for Hispanics and African Americans. From what I have seen sofar actually an increase of “Nigerian” is not always happening for African Americans, or only marginally so. Also “Broadly West African” does not seem to change that much. But in particular “Angolan & Congolese” might often show a considerable increase. Often it seems at the expense of “Broadly Sub-Saharan African”.

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Either way it seems that this upgrade is likely to be rolled out to everyone and not just so-called V-5 customers. That is to say regardless of when you tested 23andme is aiming to eventually update your results using their new algorithm. At the latest early next year, 2021. Initially there was some confusion on whether “old” customers of 23andme (genotyped on the v1-v4 chips) would also receive this update. However quite recently 23andme’s customer service made this clarifying statement on 23andme’s forum:

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In October of this year, we completed testing and validating the updated algorithm for the latest genotyping platform (v5) and decided to release this update to v5 customers while continuing to work on testing and validating the updated algorithm for previous genotyping platforms (v1 through v4). These processes are independent: the set of variants tested on the v5 genotyping chip is different from the set tested on prior chips. This means that updates for customers on current and previous chips require independent research, testing, and validation. While we cannot guarantee that the new algorithm will pass quality control checks when applied to earlier genotyping platforms, we hope to provide this update to pre-v5 customers by early next year“. (source, or see also this screenshot for complete statement)

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For the sake of correct interpretation of 23andme’s African breakdown I performed a comprehensive survey among African 23andme testers from all over the continent in 2019. This survey (based on 23andme’s 2018/2019 version) was ongoing up till now. At this point my African 23andme survey includes 314 people from 36 countries! By looking into their group averages you can get a pretty good idea on how well 23andme is able to describe the African origins of people who are already aware of their specific African lineage. Because I have been able to expand my survey I can now comment in greater detail about the predictive accuracy of 23andme’s African breakdown (2018/2019 version). Beyond what I had already established in 2019.2 In the remaining part of this blog post I will discuss the following:

  1. African surveyfindings (2018-2019 version)
    • “Nigerian” also partially describes Ewe lineage from Ghana 
    • “Angolan & Congolese” is not always fully covering Central African DNA 
    • “Sudanese” is also being reported for Sahellian West Africans, incl. Tuareg
  2. Screenshots before & after 2019 update (Africans & Afro-descendants)
  3. Screenshots before & after 2020 update (Africans & Afro-descendants)

Continue reading

Slave Voyages: not only Trans-Atlantic but also Intra-American!

This blogpost is mainly intended to announce a major overhaul for one of the most important sections on my blog:

The page referred to above is now featuring new screenshots taken from the invaluable Trans-Atlantic Slave Trade Database as well as the additional Intra-American Slave Trade Database. Reflecting the current state of knowledge. I am convinced that the data contained on that page can be very educational and useful for anyone wanting to learn more about their African roots. Just as long as you keep in mind inherent limitations and inform yourself about the relevant context. This kind of aggregated information is probably most useful on a population level.1 But also for your personal quest it can provide you with a very valuable starting point! In particular in order to judge the historical plausibility of any DNA test results you may have received. Not only regional admixture or haplogroups but also African DNA matches. And even DNA matches from across the Afro-Diaspora!2

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Despite its limitations the Trans-Atlantic Slave Trade Database (TAST) is simply the most comprehensive and up-to-date resource available when wanting to look into Trans-Atlantic Slave Trade patterns. The website was updated in 2019. It now includes information about more than 36,000 Trans-Atlantic slave voyages! See also this recommendation by Henry Louis Gates.

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““If there were a Pulitzer Prize given for historical databases, the Transatlantic Slave Trade Database would win it, hands down,” says Gates, Alphonse Fletcher University Professor at Harvard.” (source)

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I myself have often relied heavily on the Trans-Atlantic Slave Trade Database as some sort of baseline. To establish historical plausibility within my ongoing research efforts on how personal DNA test results of Afro-Diasporans may already be in alignment with historical expectations. See also:

It can be very tempting to correlate slave trade records with population genetics or assumed ethnic/regional origins of Afro-descended populations. Given the absence of more straightforward information. But such an approach can hold many pitfalls. Even if the Slave Voyages database is deemed to provide nearly fully coverage for any particular country. This is because you cannot just simply assume that there will be a direct extrapolation from the data at hand. Reality is too complex regrettably. Several factors need to be taken into account. Mainly to do with incomplete knowledge about the demographic evolution of enslaved Africans and their descendants. See the updated section for more detailed discussion. This aspect might be most pertinent:

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  • Intra-American Slave Trade, Domestic overland Slave Trade and Post Slavery migrations have resulted in great deal of additional intermingling and diversification of African lineage. This is especially true for the USA and Brazil because of their continental size. But in fact also for most parts of the Caribbean and Latin America.

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Table 1 (click to enlarge)

Based on these estimates (taken from O’Malley, 2009),  Intra-American Slave Trade for North America was around 15%. The actual shares per state do show important variation. For Virginia and South Carolina this share of slave trade by way of the Caribbean is  quite minor: around 10%. However for other states it is more substantial. Do keep in mind though that Domestic (overland) Slave Trade is not taken into account. While actually going by sheer numbers this type of Slave Trade was most significant for the USA. An estimated 1 million enslaved African Americans (often with Virginia background) are known to have been victimized by the so-called Second Middle Passage (see this link).

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Obviously there will be other factors as well that could explain genetic results being disproportionate to what you might expect based on slave trade data. Substructure within any given Afro-descended population also being highly relevant. This is something which I have blogged about several times already and also in upcoming blog posts I will return to this important topic. Within the remaining part of this current blog post I will discuss the following:

  1. Trans-Atlantic Slave Trade Database
    • Newly added Portuguese & Spanish Slave Voyages (1500’s) corroborate Upper Guinean founding effect for many Hispanic Americans
  2. Intra-American Slave Trade Database
    • Disclaimers
    • Intra-American Slave Trade Patterns for the USA
  3. Final Passages: The Intercolonial Slave Trade of British America, 1619-1807 (G. E. O’Malley, 2014)

Ancestry’s new African Breakdown: merely cosmetic changes?

Only a few weeks ago Ancestry went ahead with their ill-advised deletion of smaller DNA matches (6-8 cM). Resulting in a great loss of customer value. But already the next update is being rolled out. This time once again our Ethnicity Estimates are being reshuffled. It almost seems Ancestry is making it a yearly tradition to perform their ethnicity updates in the Autumn. Or should I say a yearly marketing ploy? Either way this is already the third time in a row! Starting with the first distastrous make-over of Ancestry’s African breakdown in 2018. Things did get better though in 2019. My verdict of last year was: “a step in the right direction but no substantial improvements for the most part. At least not when compared with the original African breakdown from the 2013-2018 version”. And really this assessment still stands also for this 2020 update. There have been a few positive changes, but nothing game changing

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Map and full listing of all the 12 African regions available on Ancestry after its 2020 update. Despite the renaming of  a few regions the only new region is “Southern Bantu”. This region will however be minimal or absent for practically all Trans Atlantic Afro-descendants.  Because of the restored “Ivory Coast/Ghana” region the West African breakdown is now more coherent than in 2019. However it still has several shortcomings…All in all nothing substantial to make up for the recent purge of smaller DNA matches.

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I find it disappointing that most of my suggestions for meaningful improvements (originally posted in 2018) have still not been taken up by Ancestry. Yet again this update seems to be centred mostly around providing greater regional resolution for Europe and Asia. The African breakdown seems to be merely a sideshow. The finer distinction to be made for Scottish ancestry is certainly striking but probably also overambitious.1 Such a focus is to be expected given that Ancestry’s customer database is overwhelmingly of European descent. While Asia probably represents a promising growth market. However the relative neglect of African & Afro-descended customer needs does go against Ancestry’s selfproclaimed goal to make their product experience inclusive for everyone. In my previous blog post I stated that Ancestry should seek to offer new tools geared to facilitate specialized research for Afro-descended customers. It should be clear that this update does NOT compensate for the loss of small African matches, earlier this month.

It is still my belief that each updated version as well as each separate DNA testing company should be judged on its own terms.2 For the sake of correct interpretation I have therefore yet again performed a comprehensive survey among 135 African Ancestry testers from all over the continent to evaluate the changes before and after this update. In addition I have also looked into a representative array of 50 updated results from across the Afro-Diaspora. These findings will be described in greater detail further below. Again for the most part no major changes. Which is why I will keep this discussion brief and only highlight the main outcomes:

  1. African breakdown for Africans before and after the 2020 update
  2. African breakdown for Afro-descendants before and after the 2020 update
  3. Is Ancestry getting sloppy?
    • When will we have genetic communities for West/Central Africa?
  4. Screenshots of African updated results

As always make an attempt to inform yourself properly without being overly dismissive. Despite shortcomings I do still think you can get valuable ancestral clues from Ancestry’s African breakdown. The macro-regional breakdown also to be taken into account to get a grasp on the greater picture. Instead of being preoccupied about the appearance of any surprising but minimal %’s. Which might very well disappear with the next update 😉 Such an approach to be combined with your remaining/salvaged African DNA matches, historical plausibility etc.. My previous discussion of the 2019 update may still offer helpful guidance. Ancestry’s FAQ is also useful:

Continue reading

Why even small African matches matter!

On 14 July Ancestry announced that they will pull the plug on the smaller matches they have been reporting for years now. In particular distant matches which show a shared DNA amount within the range of 6cM – 8cM. For many people this may effectively wipe out more than half of their total matches. Furthermore for Afro-descendants this could mean the loss of many invaluable African matches! Overall I would estimate that on average in between 50-75% of all African matches might be erased by Ancestry’s update.1 In one big drastic operation… and with just a few weeks notice…

An alarming situation for anyone who is reliant on their DNA matches (incl. smaller ones) for their research. Fortunately there are some strategies to preserve your smaller matches. Especially by contacting them, grouping them, starring them or adding notes. For more details see this overview of various helpful blog articles:

An artisanal miner holds an uncut diamond in her hand in Kimberley

A South African woman is holding an uncut diamond in her hand (photo credits) African DNA matches can be as illuminating as diamonds. Even when small in size they can still be priceless! However carefull assessment is a MUST when dealing with potentially false matches because otherwise you’ll only end up chasing fool’s gold 😉

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In this blog post I will focus on the importance of smaller African matches. Something which has been revealed to me in my ongoing research on African DNA matches since 2017.2 Even when indeed many of them will be false matches. Precious informational value may still often be obtained. But it seems that this importance has not really sunk in yet with Ancestry or perhaps they have other priorities… Either way Ancestry’s announcement has been brutally abrupt and will catch many people by surprise. 

I hold no illusions about a complete reconsideration of this update (I love to be proven wrong though!). However I do hope the main arguments listed below may at the very least persuade Ancestry to delay their intended update. Even more so I wish that they wisen up and instead will implement tailor-made solutions which take into full account the diversity of their customer needs! If you agree please forward this blog post to Ancestry! For example in this suggestion box. See also the last part of this blogpost.

  1. Added value of small African matches
  2. Dangers of small African matches
  3. Appeal for true committment

 

Why even small African matches matter!

  • Afro-descendants face exceptional challenges when Tracing African Roots. Given the lack of a paper trail for the most part they have to go by any clues given! Out of sheer necessity the net has to be cast wide. An openminded and creative research approach is required. Both including but also going beyond genetic genealogy. All the while avoiding source snobbery in order to maximize any potential informational value.
  • Ancestry offers the biggest pond of African matches by far, when compared with other DNA testing companies. In great part because of its lower matching threshold which starts at 6 cM. This has been a precious resource for many which cannot be found elsewhere. It will be a tremendous loss when this pool of African matches will no longer be available or shrunk to a mere shadow of its former size!
  • Smaller matches may serve to reinforce more solid ancestral clues provided by related bigger matches (for example sharing the same meta-ethnic background). When combined with associated regional admixture and insights from other fields possibly leading to fruitful complementarity. See for example my survey of African DNA matches reported for 30 Jamaicans.
  • Small matches will indeed often be false matches or genealogically irrelevant but they may still be historically relevant (given correct interpretation). Leading to more insight of one’s African heritage within a greater timeframe. In particular when appearing with increased frequency. See for example my survey of African DNA matches reported for 50 Cape Verdeans.

Continue reading

African DNA matches reported for 30 Jamaicans on Ancestry

In this blog post I will analyze the African DNA matches being reported by Ancestry for 30 of my Jamaican survey participants.1 A follow-up to my previous blog post about 100 Jamaican AncestryDNA results (see this link). Most important finding arguably being that Nigerian & Ghanaian predominance in regional admixture (2013-2018 version) for Jamaicans is also reflected in their DNA matches. Notwithstanding recent updates on Ancestry 😉 Furthermore there is no longer any excuse NOT to be looking for African DNA matches. I found on average almost 30 African DNA matches for each one of my survey participants!!! There are plenty of Africans who have tested with Ancestry by now. So you only need to search for them and then you will be rewarded with greater insight and closer connection to your African heritage! See also these links:

Because I was given access to their profiles on Ancestry I was able to use my scanning and filtering method of DNA matches in Excel. Aside from African matches I will also be including Jewish and South Asian matches in my discussion. Below a statistical overview of my main findings. Going by group averages. For the individual results which do display greater variation follow this link:

Table 1 (click to enlarge)

Stats (n=30)

All of my 30 survey participants received African matches. Also I was able to find 5 close African matches (>20cM)! On average 29 African matches were reported for each person. Around 80% of all African matches are connected to either Nigeria (16/29) or Ghana (7/29). The African admixture averages are based on the old 2013-2018 version of AncestryDNA. As I believe that despite shortcomings this version still offers the best fit for Jamaica’s known regional roots within Africa (see this link). Calculation of average & maximum shared DNA is based on the outcomes per survey participant. In all other tables below it will be calculated based on all DNA matches taken together.

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Table 2 (click to enlarge)

Afro Matches

The background column is mostly based on informed speculation (plausible surnames/regional admixture) but at times also confirmed by public family trees. The proportion of West African (Lower Guinea) related matches is 87% (755/861) of all African matches. The high number of especially Nigerian Igbo matches is quite striking. Undoubtedly due to very substantial ancestral connections. But possibly also a bit inflated within this overall overview. Reflecting a greater popularity of DNA testing among Nigerians as well as Ghanaians when compared with other Africans. Francophone & Lusophone migrants still tend to be  greatly underrepresented in Ancestry’s customer database. In particular it seems from Central Africa as well as Benin & Togo.

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This project was merely intended as an exploratory exercise. Of course my research findings have limitations in several regards. And therefore they should be interpreted carefully in order not to jump to premature or even misleading conclusions. Still I do believe they can reveal relevant tendencies in African DNA matching patterns for Jamaicans in general. These outcomes may also provide valuable insight into the various ancestral components found within the Jamaican genepool. Contributing to answering major questions like: Do Jamaicans have more Nigerian or Ghanaian ancestry? In particular when aiming for complementarity by also taking into account admixture analysis, genealogy and relevant historical context.

Below an overview of the topics I will cover in this blog post:

  1. Considerations when dealing with DNA matches
  2. Combine DNA matches with admixture analysis for more insight
  3. West African matches: as expected Nigerian and Ghanaian DNA matches were clearly most numerous. Only a subdued number of matches from Upper Guinea. This outcome is roughly in agreement with a predominant Lower Guinean macro-regional share of around 70% I calculated for 100 Jamaicans, based on admixture (see this chart).
  4. Central & Southeast African matches: quite low in number. In contrast with often substantial “Cameroon/Congo” scores being reported for Jamaicans. Interestingly Cameroon is relatively well represented.
  5. Other African matches: unexpected & uncommon. Higher odds of false positives but in some cases to be corroborated by distinctive admixture?
  6. Substructure: are there any group differences according to admixture level, “genetic community” or parish?
  7. Jewish & South Asian matches: disproportionately numerous whenever backed up by associated admixture (even in trace amounts!)
  8. Methodology: describing how I filtered the African & non-African DNA matches as well as the decision rules I applied when determining a plausible background for each DNA match.

Continue reading

The Mozambique connection on Ancestry & MyHeritage

Mozambique is a somewhat overlooked country of origin for many Afro-descendants. To be sure the Trans-Atlantic Slave Trade with Southeast Africa was relatively smaller in scope than with either West or Central Africa. Still according to most recent estimates it involved almost half a million people (see this overview from the TAST database). Especially for Brazilians, Haitians and Cubans Mozambican lineage might be considerable in some cases. Plus also the Indian Ocean Slave trade is to be taken into account. Which most likely resulted in a dispersion of a similar number of Mozambicans (see this overview, taken from this paper). Especially into South Africa and the Indian Ocean Islands: such as Mauritius, Réunion and Madagascar. But also to the Middle East and into South Asia and beyond even. For more details:

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Map 1 (click to enlarge

Kaartje MH

I found 12 most likely African matches for a person who is himself 1/2 Mozambican and 1/2 Portuguese. Most of these matches actually were likewise of mixed background. With the majority being from South Africa (6x). But also tellingly one single close match from presumably Pemba, Mozambique! MyHeritage provides a very useful filtering tool which allowed me to zoom into shared East African DNA segments among this person’s DNA matches.

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Then again some people might also have Mozambican ancestry due to recent migrations. In the last couple of months I have been given access to DNA results which reveal an already confirmed Mozambique connection for two people of mixed background. With very fascinating outcomes! As well as useful implications for other people wanting to learn more about their own possibly Mozambican lineage.

The first person is living in the Netherlands (like me). Both of his parents were born in Mozambique. But going back two generations his father’s grandparents are all of Portuguese descent. While his mother’s family has been living in Mozambique for as long as can be traced back. But her family tree does contain at least two persons who were born in India and migrated to Mozambique as well. When it was still under Portuguese rule. All in all a very fascinating tale of migration across several continents! This person tested with MyHeritage and he has been featured in a Dutch documentary series called “Identity”. I was actually honoured to also contribute to this documentary which was shot in my birth place Rotterdam. The actual day of filming being the 5th of July which happens to be Cape Verde’s Day of Independence! Highly symbolic for me therefore 😉 1 See also:

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Figure 1 (click to enlarge)

STP

These are the recently updated AncestryDNA results of a person whose father is from Mozambique. His Southeast African DNA is clearly indicated by his main regions, incl. also “Eastern Bantu”! Another intriguing aspect is that this person actually also has a Cape Verdean connection by way of São Tomé & Principe. This is revealed by a very distinctive score of 6% “Senegal”. Probably also to be combined with the “Portugal” & “Spain” scores. Highlighting that regional admixture DOES matter!

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The other person is a DNA cousin of mine on Ancestry whose mother was born in São Tomé & Principe while his father is from Mozambique. I am related to him by way of a mutual Cape Verdean relative who migrated to São Tomé & Principe as a contract labourer during the first half of the 1900’s. São Tomé & Principe is a former Portuguese colony just like Cape Verde and Mozambique. But nowadays it is an independent island state located nearby Gabon in the Gulf of Guinea. Just like Angolans and Mozambicans many Cape Verdeans ended up settling in São Tomé & Principe during the Portuguese colonial time. Notoriously being employed under very harsh circumstances on the cocoa plantations of São Tomé & Principe. It therefore still has a sizeable community of Cape Verdean descendants. Their continued longing for their motherland has been made world famous by the song “Sodad” by Cesaria Evora (see this video clip).

This blog post will describe the DNA results of both persons. Seeking to demonstrate in particular how correlating regional admixture analysis with DNA matches can be rewarding and mutually reinforcing in many cases. In addition I will also discuss my experience with MyHeritage. As I have myself not tested with this company. And so this was the first time I had the chance to get acquainted with several of its features. Allowing me to also make some cross-comparisons with Ancestry.

  • Mozambican Connection on MyHeritage
  • Mozambican Connection on Ancestry
  • Comparing Ancestry with MyHeritage
    1. MyHeritage is distorting Central & Southeast African DNA
    2. Ancestry offers greater potential to find African matches
    3. MyHeritage provides more advanced filtering tools

 

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