In this two-part blogseries I will analyze the DNA matches being reported by AncestryDNA for 50 of my Cape Verdean survey participants. A follow-up to my previous blog post about 100 Cape Verdean AncestryDNA results (see this link). Because I was kindly given access to their profiles I was able to use my scanning and filtering method of DNA matches in Excel (see this link). Aside from matches with mainland Africans I am also including matches with people of (presumably) fully Portuguese, Jewish, West Asian and South Asian descent.1 Below a statistical overview of my main findings. Going by group averages. For the individual results which do display greater variation follow this link:
This table is based on group averages. Except for the columns mentioning the frequency of close and zero matches. So for example among my 50 survey participants only one single person received a close African match (>20cM). While two persons did not receive any African matches at all (excl. North Africa). But on average 5 African matches were reported of whom 4 were connected to the Upper Guinea area. (Senegal-Sierra Leone). The average admixture amounts are based on the recently updated Ethnicity Estimates on AncestryDNA. This update strongly reduced the trace regions. Especially for North African & West Asian DNA. For a previous version of this table see this link.
Table 2 (click to enlarge)
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 Upper Guinean related matches is 88% of all African matches (south of the Sahara). That proportion being equal to 227/257. Excluding North African matches from the total. The high number of Fula matches is quite striking. But this could very well reflect a greater popularity of DNA testing among Fula people when compared with people from for example Guiné Bissau who are greatly underrepresented in Ancestry’s customer database.
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 DNA matching for Cape Verdeans in general. These outcomes may also provide valuable insight into the various ancestral components found within Cape Verdean DNA. In particular when aiming for complementarity by also taking in to account admixture analysis, genealogy and relevant historical context.
Below an overview of the topics I will cover in this blog post:
Considerations when dealing with DNA matches
Upper Guinean matches: as expected African matches (south of Sahara) were overwhelmingly from Upper Guinea (Senegal-Sierra Leone): 88% of the total. In line with the 92% Upper Guinean admixture proportion (“Senegal” + “Mali” / total African) I found for my survey group.
North African matches: fairly consistent despite minimal shared DNA
Other African matches: unexpected & uncommon. Higher odds of false positives but in some cases to be corroborated by additional clues, such as AncestryDNA’s ethnicity estimates?
Methodology: how I filtered the African DNA matches as well as the decision rules I applied when determining a plausible background for each DNA match.
Part 2 of this blogseries will have the following topics:
Portuguese matches: omnipresent and clearly most numerous as well as often hinting at relatively recent ancestral ties (1800’s-1900’s).
Jewish matches: Sephardi matches more likely to be truly genealogical than Ashkenazi matches?
West Asian matches: quite rare, possibly indicating that West Asian admixture among Cape Verdeans is generally indicative of actual North African or Sephardi lineage.
South Asian matches: also rare, but on a hit and miss basis still sometimes already seemingly validating trace amounts of South Asian admixture.
Inter-island matching patterns: illustrated by the distribution of the shared DNA segments between myself and my 100 Cape Verdean survey participants.
Methodology: how I filtered the non-African DNA matches as well as the decision rules I applied when determining a plausible background for each DNA match.
Dedicated to all my Cape Verdean primos and primas participating in this survey.2 And special dedication to my newly born nephew Max!
Wishing to share the vibranium 😉 I have created a new page featuring the DNA matches reported by 23andme for 75 Africans, all across the continent. These results were collected by me in 2015 when 23andme’s Countries of Ancestry (CoA) tool was still available.
My survey results might have limitations in several regards but I do believe these African CoA results can still reveal relevant tendencies in DNA matching. I intend to compare these preliminary matching patterns eventually with my more recent findings for Africans who tested on Ancestry. I provide detailed background info as well as screenshots of the individual results on this page:
This blog post features the AncestryDNA results of 8 persons from 7 different countries. In particular i will list the (most likely) African DNA matches i was able to find for each profile. Using the tutorial i blogged about in my previous blog post:
Naturally this overview is not meant to be representative per se because these persons are in the first place individualswith unique family trees. It is mainly to show the variation across the Afro-Diaspora. Nonetheless I strongly suspect that many patterns to be observed will still be valid as well for other people of the same nationality or ethnic (sub)group.
***(click to enlarge)
For this overview I specifically chose people with one single predominant African regional score on AncestryDNA. In order to see how Ancestry’s “Ethnicity Estimate” lines up with predicted African DNA matches. More detailed analysis will follow in this blog post. If you continue reading you will also come across a section featuring inspiring stories of people who were able to reconnect with their African kin through DNA testing.
Ethnicity summary of my most likely Gambian DNA match on Ancestry.com
Because of the new Compare tool I have now (November 2018) also learnt that his main region is 81% “Senegal”(pre-update). I cannot see the remaining part of his breakdown though.
A couple of months ago I found my very first mainland West African DNA cousin on Ancestry.com. Judging from his name and ethnicity preview he is a Mandinga from Gambia. I was exhilarated! I had never been able to find a mainland West African match before. Even when I took my first DNA test with 23andme already in 2010! In other words I had to wait seven years for it! Inspite that I haven’t had any meaningful contact yet this genetic connection is still very valuable to me. As I am of Cape Verdean descent this finding seems very appropriate and in line with my primary Upper Guinean roots (see Top 20 Ethnic Roots for Cape Verdeans).
Many people seeking to trace back their African ancestors are very eager to be connected to a specific place and person within Africa. They hope to achieve this by finding a DNA match from the continent. But just like me they are having a hard time to do so. In the beginning this was mostly because only very few Africans were included in the customer databases of companies such as 23andme or Ancestry.com. Fortunately this has been changing lately because a quickly growing number of Africans or rather African migrants and their children are taking a DNA test. This increases the likelyhood of receiving African DNA matches. However many people still find it difficult and/or tedious to sort out their DNA matches. In this blog post I will therefore describe a method which enables a systematic, comprehensive and time saving detection of your “100% African” DNA matches on Ancestry.com.
If you continue reading you will find:
Some considerations on how to interpret your African DNA matches
A step by step tutorialon how to sort out your African DNA matches