My Goodness My Guinea-ness?

By Razib Khan | April 1, 2011 12:20 am

Update: After this post a researcher who is planning on publishing work on the genetic structure of Great Britain and Ireland and who has a very large N forwarded me a PCA which he gave me permission to repost. I’ve uploaded it here.

As you might infer from the post below I’ve started to get interested in African population structure. It’s not just me. Readers regularly query me about the relationship of various groups, such as the Nilotic peoples who reside amongst the Bantu in northeast Africa. Additionally, there is a consistent problem with 23andMe generating weird results for people of African ancestry, usually those with East African ancestry.

But to figure out the nature of African variation in more detail we also need to give some thought to outgroups. My initial assumption was that using Tuscans would be sufficient, but several people pointed out that many Mediterranean groups have trace African admixture. Probably not enough to matter, but why take the risk? So how about looking to Northern Europe? The Utah Whites and Orcadians jump out as plausible alternatives, but there was a third which I thought I’d try out: the Irish.

Last fall my friend Paul bought a bunch of 23andMe kits for family and friends, and convinced others of his acquaintance in Ireland to do likewise. Over the past few months we have given considerations to exploring the genetic relationships of Europe’s “Atlantic peoples.”  We were thinking of terming it “The Milesian Project” (after the legendary Milesians who sailed from Galicia to Ireland). We now have 26 people with four Irish grandparents, from the modern Republic of Ireland, or with ancestors who derive from the Republic of Ireland. The vast majority of these are Roman Catholic, presumably the descendants of Gaelic speaking peasants.

For various reasons The Milesian Project hasn’t gotten off the ground, but, we do have a reasonable sample of Northwest Europeans now which is not the generic Utah white or Orcadian sample. Over the past few weeks the last dozen of the samples came in. There was mention of false positives in the ancestry painting, but I didn’t think much of it. What I found surprised even me. I’m thinking of diversifying my African outgroups soon, so I wanted to poke around the Irish for weird outliers or people who were too closely related (you never know). Here’s a plot of a supervised run where I set Utah whites and Yoruba as the two population poles:

No need to do a double take. The Irish have more West African than the Tuscans! What’s going on here? Here are the individual plots for just the Irish:

Most of the African ancestry is found in only five individuals. I asked Paul to inquire, and these were the individuals with unexpected ancestry paintings showing African ancestry. They’d all assumed it was some fluke. But here’s a bigger coincidence: most of the Irish samples are from the east, but all of these individuals have most of their ancestry (at least 3 of 4 grandparents in 2 cases, and all 4 in the other 3) from a few villages to the west of Cork in the south of Ireland! According to Plink these individuals are not particularly closely related (they don’t show up in each other’s Relative Finder feature either).

I think the most plausible explanation for what’s going on is that some West African seamen who arrived in coastal Ireland because of the British Empire intermarried with locals. The memory of their exotic origins has faded, but the genomic impact is clear.

As for using Irish as outgroups, I’m just discarding these individuals for future runs. But I’m curious if any Irish readers have noticed anything strange about this region?

CATEGORIZED UNDER: Genetics, Genomics
MORE ABOUT: Genetics
  • Barry Cotter

    Nope, nothing terribly strange. I assume you know about the Spanish looking people on the West Coast, who seem to be mostly Basque-esque remnants from before the Celtic agricultural/cultural package showed up.

  • Paul Ó Duḃṫaiġ


    If you want I’ll send you my sample I’m v3 tested. Most of my family (3/4ths) is specifically from the West of Ireland. Regarding african admixture, interesting enough the Insular Celtic languages (Irish, Scottish Gaelic, Manx, Welsh, Cornish) are unusual in Indo-European context by having a VSO (Verb-Subject-Object) structure. Most other languages are SVO (Subject-verb-object)

    Other VSO’s languages are:
    Classic Arabic
    Classic Hebrew
    Berber Languages

    (I’m leaving out the asian examples)

    It’s been theorised that the pre-IE (Celtic in our case) population in Ireland spoke a VSO language that had a substratum affect on the incoming Celtic speakers. Gaulish which is a continental-celtic language appears to be SVO unlike it’s near relative “Old Irish”.

    Interesting enough our mythology talks about a race called the Formorians who lived on Tory Island off the north-west coast of Ireland, one story tells how they were originally seafarers from Africa.

    As for south-west coast of Ireland, there was alot of slave raids done in that area by the Barbary pirates. Over 100 people were taken when they sacked Baltimore (origin of placename in MD) in 1631 and sold into slavery in Algeria.

  • Mike

    On a completely non-scientific basis, asking if there is something strange about the area west of Cork is like asking is there any odd people in the madhouse. Its an area with very much its own character, to the extent that it is normally referred to as an area in its own right (West Cork). From the 60’s to the 80’s it recieved a large influx of New Age Travellers due to a belief that in the case of a global nuclear war, prevailing weather conditions would keep it essentially safe from fallout. That is too recent to affect genetics, but it does give the area more of a multi-cultural tinge then you would expect.

    On a wider basis you could probably replicate your findings anywhere along the coast from Carnesore in Wexford around to Gweedore in Donegal. I wuld suspect if you were to try to compare markers to the northern Spanish or Portuguese, you would probably also find some correlation. My own family is from the Mayo area and tend towards sallow skin, and black hair (not particularly indicative one way or another of any specific place, but not very Celtic either!) . The city of Waterford on the south coast had for a long while a language of its own (now I believe extinct) based around the port known simply as “The Lingo” which supposedly was a mix of Irish, pidgin English and words taken from North African and European languages.

  • Maju

    North African influence tends to show up as “Yoruba” when only CEU/YRI are used for reference. I just discussed yesterday night a new PLoS ONE paper using EuroAIMS which does not detect any YRI introgression not just in Iberians but neither in North Africans either (however these markers are selected to discern between populations, so these small amounts of admixture may not show up).

    In any case North African influence may (and should) show up as West African when a North African specific reference is lacking. IMO it is more likely that the YRI component in this area of Ireland actually reflects North African influences via West Iberia in the Neolithic/Chalcolithic (Megalithic) period. West Iberia does show a 9% of North African genetics (clearly so).

    Inversely, if you’d use East Asian and Tuscan samples instead of Yoruba and CEU as poles of the supervision, CEU themselves (and probably Irish too, because they are so close to CEU) should show up with some “East Asianness” – probably indicating minor “Finnic” admixture, in turn somewhat related to Siberia, etc. Clinality tends to show up and a lot depends on which reference poles you chose.

  • DavidB

    There were a lot of black or mixed race seamen in British merchant or navy ships in late 18th and 19th centuries. (And for that matter in American ships – read Melville.) Not necessarily directly from West Africa, but also from New World slave populations, e.g. runaway slaves who joined British forces in the war of independence. I’ve no idea if any of them ended up in Irish coastal towns, but it’s not impossible. Another possible source would be from black servants of wealthy families. They were fashionable in England in the C18, so I guess the Anglo-Irish upper classes would follow suit.

  • bob sykes

    The Celts may have originated somewhere near the Balkans/Anatolia and migrated along the Mediterranean coast to Spain and then up the Atlantic coast to Britain. So there would have been ample opportunity to pick up African genes. The Tuscans may be a more recent intrusion into the Mediterranean regions.

  • Diogenes

    Are you sure this is being correctly interpreted as West rather than (North)East African?
    I have a sample in my recent run who I didn’t include, from Portugal (no prizes for guesses who that is), and it has >6% !kung. And I’m quite sure this individual is not ancestrally from the coastal plain :), but all of Portugal is rather close to the coast. This is well in excess of average for Spaniards. Most Spaniards are kind of homogeneous at 1-3% but some Spaniards have less and one has 6% too. Most Spaniards in the sample I have may be from Castillian regions in the meseta…
    I’m guessing this is a Neolithic second wave from the Fertile Crescent (Nile River Valley Core Area?), and that it affected coastal Med populations disproportionatelly, maybe up to Cork. Black Irish legends?

  • Paul Ó Duḃṫaiġ


    “Black Irish” is very much an american myth. The term is never used here in Ireland apart from when talking about americans and their usage of term.

    Here’s an image which fits the typical “Anglo-Saxon” view of the Irish — From Harpers weekly and american political magazine of 19th century:

  • John Farrell

    That does it! My mother’s parents were from Cork. My father’s from Dublin. I need to get a 23andme kit!

  • Diogenes

    By the way an “Egyptian wave” superimposing itself partially on an earlier “Mesopotamian wave” is not incompatible with Maju’s idea, since any Egyptian Neolithic wave probably affected North Africa very strongly, and may have spilled from there into the Iberian coast and Northwards.

    Also a “Celtic Agricultural/Cultural package” with a major demographic impact is nonsense IMO, except if you mean “East wave” (from Anatolia through the Caucasus) peoples through the Corded Ware melting pot region with Rye. After the first few waves, innovations by similar neighbouring peoples likely have less and less of a demographic impact (decreasing quickly towards zero). Also I don’t see what a “Celtic look” is supposed to mean when speaking of ancient Celts. Nobody knows for sure what the earliest Celtic speakers looked like. I would venture that “Black Irish” from Cork were likely the very first people in all of Ireland to speak proper Celtic, and maybe were involved in its development as a lingua franca with other Atlantic communities (see Cunliffe).
    Tartessian as Celtic is gaining increasing acceptance and I would bet they didn’t have (much) red hair. Also “Celtici” for Greeks and Romans mainly meant Southwest Iberians. French and even British Celts were often lumped as Gauls.

  • Dienekes

    I have one of these West African admixed Irish in my project, as well as another seemingly South Asian admixed one. Both are clear outliers with respect to the Irish population. Normally I would be dubious of these results, as some people have tried to circumvent the 4-grandparent rule in order to get their data analyzed, but it could also be a real phenomenon. Since you probably have most of the same participants as I do, it would be worthwhile to do a 3-population test to see if you also have the South Asian-admixed individual, and this might lend some support to the “British Empire” theory.

    I do not, however, believe that these individuals are the result of a few African segments grafted onto a basically Irish population, since the individual in question also differs with respect to their European components and has an excess of South European and a deficiency of North European.

  • David A

    This is interesting stuff, and potentially very controversial for the region I study: the Great Lakes of central Africa. As you probably know, disagreements over the origins of the Hutu and Tutsi populations have led to repeated bouts of violence and even genocide. I wonder if there is any solid data on this question. Certainly my own experience suggests that while it can be difficult to determine the ethnic identity of many Rwandans, there are some “ideal types”–just as there might be if you were trying to tell Italians from Swedes, for example. What can genetic testing tell us about whether the two groups have distinct ancestries, how much commingling there has been, and when that commingling might have begun?

  • adam

    As another N, my father’s side is pretty purely Scottish; we even have a family tree which, if there was no hanky panky, suggests that my father’s father’s father (etc) were Scottish into about the 800s. And when I got my 23andme results back what haplotype did I get? E1b1b1a2* which is almost entirely localized in northern and eastern Africa. I think there was more Roman influence in British genetics than people tend to think.

  • Eze

    That’s completely unexpected, African ancestry in Ireland? Wow.

    You could use RHH counter to see whether this is recent or ancient stuff.

  • gcochran

    The Hutu and Tutsi are pretty different when it comes to lactose tolerance and sickle-cell: high lactose tolerance and almost no sickle-cell in the Tutsi. At the same time, you see some lactose tolerance among the Hutu, enough to suggests that there has been a fair amount of intermarriage over the generations.

    If you gathered some SNP data, you would know more, but the two tribes obviously haven’t been close neighbors forever.

    Some anthropologists have argued that the idea that these two peoples have different origins is incorrect, but they’re just blathering.

  • ohwilleke

    Looking at the data, a greater British colonial source makes more sense than a megalithic or bronze age or iron age source.

    If the African component dates to the Celts or Romans it would be much more evently admixed among the Irish generally, not localized to a handful of individuals in one highly localized part of Ireland. You would have lots of individuals with very low levels of African admixture in a fairly broad geographic range the way that you do in Iberia, not something that you find not at all in 17 individuals, at fairly high levels in 5 individuals, and at very low levels in 2 individuals.

    I would speculate that the most likely possibility would be that some descendants of English colonists in Africa (or more likely the Caribbean) secured posts with the British colonial administration in Ireland and had children (quite possibly out of wedlock and unacknowledged) with local girls, who subsequently blended into the local population. Mixed race Afro-Caribbeans intentionally sought to maximize the white portion of their admixture over many generations, so the possibility that a British national Caribbean mixed race individual could have passed for white upon arriving in Ireland as part of a British colonial administration is reasonably good, and there would have been adminstrative overlap between the British colonial management of its Caribbean colonies and its management of Ireland. “Pass for white” Afro-Carribean sailors who ended up in Cork would seem the second most likely option.

  • Razib Khan

    After this post a researcher who is planning on publishing work on the genetic structure of Great Britain and Ireland and who has a very large N forwarded me a PCA which he gave me permission to repost. I’ve uploaded it here

  • Ian

    Setting aside the inconvenience of reality for a moment, I’m going to invoke the Spanish Armada (since no one else did). Could have come up with a whole long story of some enslaved Africans working on one of the ships who made it to shore after the ship they were on broke up.

    I have a feeling a Mills & Boon (presumably they still exist?) author could take an idea and run with it… :)

  • EcoPhysioMichelle

    I knew something was up when I saw the filename.

  • Eze

    LOL, very original prank.

  • Paula Helm Murray

    I’d like to know. I am an adopted child, adopted in the 50s in Missouri, and I could be dying and there would be no legal help getting info about my birth family.

    And my adoptive parents are: German/English on my father’s side, Cherokee or etc. Indian (NE OKla.) on mom’s. I don’t look like anyone in my family. But I’m fair, have reddish hair, etc. When I visited Dublin in 2005 on my way to the Glasgow World Science Fiction convention it was very strange because I saw people on the street that Looked Like Me.

    I don’t have the bucks to find out about genetic heritage, I’m employed now but was unemployed for over two years and the expense makes it frivolous. but it was a very striking observation.

  • ryan

    I’m a little unclear – the update link and the “researcher with a very large N” is obviously a joke, but was the whole post an elaborate lead-in to that joke? I don’t think so. I think the original post on the handful of Irish in a sample with seeming African ancestry is a genuine post. If not, can someone clue me in?

  • Lubo


    The whole post was a joke. The Irish have one of the least diverse gene pools in Europe. If there was any sub-Saharan African ancestry in the modern Irish population, it would likely have been identified before now.

  • Blackbird

    People keep referring to the Spanish and its large African admixture, alas, I am 100% Spanish and in the 23andme results, 100% European, falling in the diversity of French, German and Austrian. Does anybody know of published regional distribution of African ancestry in Spain? Is the whole post a prank?

  • pconroy


    Check for an “Irish” participant, I think his name is Quinn, who mentions in his 23AndMe profile that one grandmother is Czech – yet he continually refers to himself as 100% Irish in many blogs and fora?!

  • pconroy

    Awesome prank!

    BTW, DeCodeMe says I am 1% Sub-Saharan – but no other project has found that at all.

    I recently came across a blog that tries to make the case that:
    Black Irish = Sephardic Merranos

    There is much circumstantial evidence that Portuguese/Spanish Merranos settled in Ireland in the 1500’s – including the first Jewish mayor of any city/town in Ireland or Britain, William Annyas, who was elected to that position in 1555 in Youghal on the Southern coast of Ireland:

    This could explain how I and a few other 100% Irish people are getting Ashkenazi and Sephardic matches – from places as far away as Iran and Iraq…

  • onur

    DeCodeMe says I am 1% Sub-Saharan – but no other project has found that at all.

    deCODEme generally overestimates minority elements.


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About Razib Khan

I have degrees in biology and biochemistry, a passion for genetics, history, and philosophy, and shrimp is my favorite food. In relation to nationality I'm a American Northwesterner, in politics I'm a reactionary, and as for religion I have none (I'm an atheist). If you want to know more, see the links at


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