Echoes of the East-African Slave Trade - Distant Diasporic Matches - IBS or IBD?

[Angoliga]

This thread is intended for Central-East Africans that have found distant relatives in the Americas and beyond -- all others, please feel free to share your opinion on the validity of distant-matches in the 5cM-7cM range (albeit, within the scenario of isolated/removed populations). I've been forewarned of common overlapping segments in populations that give misleading detections.

Please feel to state:

-your ethnicity
-amount of diasporic matches found
-their locations
-range of detected relations (ex. 5-30cM - 7th to distant cousin)



My summary:

-parents are both several generations Ugandan + bordering Sudan/DRC of Central and Eastern Sudanic speakers
-in total, my mother, four siblings and I have 100 odd matches
-Most had 19th century ancestry in the US; the states of VA,SC,MS and TN were reported among the highest from the responses of my matches. A man of complete Jamaican ancestry, along with 2 Puerto Ricans (both related to each other as possilbe 3rd cousins (4.2 gens)), 2 Cubans (both of the Perez surname) were found detected in the Caribbean. As well as a person of Cape Verdean ancestry and another match from the island of Mauritius -- to me his detection was a blatant connection of the East-African slave trade.
-All detected matches were in the range of 5cM to 7.9cM


I hadn't known the extent of the Arab/Swahili slave trade until my immediate family and I found distant relatives on 23andMe and GEDmatch. We later found a biochemist's paper on regional Ugandan mtDNA which found identical mutation sequences among Hispanic and African American populations. This along with historical documents from the 19th century, gave more information for me to believe these matches could actually be real.

The East-African slave trade is seldom mentioned in comparison to the West-Africa, rightfully so since some estimates place captured East Africans at under 5 percent of the total Atlantic slave trade.

Several DNA vendors have set higher thresholds to offset the high percentage of IBS detections found among older colonial as well as Jewish/Hispanic customers due to Endogamy. I'm skeptical of thinking a high percentage of my family's matches are IBS, for the simple fact that the gene pool of my parent's region has been isolated for centuries smack in the middle of Africa. The way I see it, any detection over the stated 5cM 500SNP threshold can't be seen as ancient and must be the result of a common ancestor in the last 200 years or so.

I've also found other East Africans on GEDmatch, a Kenyan and a Tanzanian, who also have diasporic matches from 4th generation (possible 3rd cousins) to distant. Their closer proximity to the coast was probably the main factor of them having closer related matches and more matches overall. I don't want to ramble more than I already have, I'll comment on some interesting findings between my matches when more members have shared their own experience.

[Morci]

Very interesting. I'm African American and I remember having sizable matches to East African nations on 23andMe. There were two from Kenya and one from Uganda. I also had a match from Botswana.

[Angoliga]

Thanks for sharing Morci! Care to share the details of your East-African matches (ie. estimated relation, size of shared segments)

Thx!

[drobbah]

Majority of the East African slaves were sent to Arabs(Arabian Peninsula),Horners(Somalis in particular) and then the rest of the nations on the Indian [email protected] do you know of any historical evidence which proves East Africans were sent to the Americas in large numbers?

[Deftextra]

The majority of my distant matches on ancestry DNA are south american. I match with a few Somali's distantly and a bunch of these matches are before some Somali matches, which is strange (But as Awale pointed out, this is likely because southern Somali's are under-represented). I know the coastal communities in southern-Somalia and the Benadiri's are to some extend the product of the Indian ocean trade, but my ancestry shows that intermixing seems to be limited to the western Indian-ocean (which makes sense given the monsoon winds). Anyway, I could not find any evidence of large scale interaction going on between Americas and east-Africa. But given our mixture, there could be a ton of different possibilities.
This is how my closest 2, south american matches looks like.

Edit: I think the first one is Polynesian actually? Interesting.

Regions: Asia East, Native American, Polynesia, Asia South
Trace Regions: Iberian Peninsula, Italy/Greece, Asia Central, Africa Southeastern Bantu, Scandinavia, Ireland, Caucasus, Mali

Regions: Native American, Iberian Peninsula, Africa North, Italy/Greece
Trace Regions: Asia Central, Ireland, Middle East, Nigeria, Asia South

[Angoliga]

@drobbah, correct - the destinations of East-African slaves has been historically dominated by destinations in the Arab world as well as other locations in and around the Indian Ocean -- no ones refuting that.

What would you quantify as large numbers?

From the sources I've come across, which are scant at best, I can't recall any reporting any "large numbers" from ports on the Swahili coast (north of Zanzibar) to the Americas. It's generally agreed, the transactions of the Swahili/Arab slave trade weren't nearly as well accounted for compared to the more commercial European dominated trade on the Atlantic coast.

This is a quote from "Slave trade and slavery on the Swahili coast (1500-1750)" by Dr. Thomas Vernet; it summarizes the difficulty of historians quantifying the scale of the trade but offers some numbers:

Because of the lack of sources, it is not possible to estimate the scale of the slave trade in the sixteenth century. Figures do exist in the seventeenth century historical documentation; however, these derive from scattered Portuguese and English sources that must be treated cautiously. A few scholars have offered estimates of the slave trade on the East African coast. Austen asserts that an average figure of 3100 slaves were yearly exported between 650 and 1920, but this covers such a large chronological period that his estimate seems questionable, more so because he does not cite his evidence. 167 Lovejoy makes the assumption that around 1,000 slaves were shipped each year to Arabia in the seventeenth century,168 but this appraisal is not supported by the assessments given in contemporary documents.

Here's a visual representation of the slave trade with a visual comparison of estimated numbers for destinations Overview of the slave trade out of Africa, 1500-1900. David Eltis and David Richardson, Atlas of the Transatlantic Slave Trade(New Haven, 2010) :
[IMG]www.un.org/en/events/africandescentdecade/assets/img/slave_trade_map_large.jpg[/IMG]

This paper references a source from Great Britain, Parliamentary Papers (1845), XLXm "Slave Trade-Slave Vessels" report printed 25 Feb. 1845 - the main paper is titled the Cuban Slave Trade - 1790-1843: https://www.academia.edu/2484872/Cub...rade_1790-1843

Refer to the chart on page 82 for an average of slaves leaving East-African ports and arriving in Cuba between 1820-1843. The collective grouping for East-African ports most likely refers to ports in Portuguese controlled Mozambique as opposed to Swahili controlled ports further north in Zanzibar and Mombasa. These enslaved persons came from a multitude of different ethnic groups in the East-African region because of the extensive network of the trade, one couldn't exclude slaves captured from areas outside of Southern-East Africa ie. persons of Bantu/Nilotic origin stretching as far inland from directions of the Great Lakes region or Southern Ethiopia.

[Lank]

You mentioned having Kenyan/Tanzanian (presumably Bantu-speaking?) relatives at 23andMe, did you check their matches as well? Some Bantu speakers have relatives from distant parts of Africa. In a way this is unsurprising, since Bantu speakers share recent common ancestry. What I'm thinking is perhaps your New World matches are indirectly traced to your Kenyan/Tanzanian relatives, who in turn may have had relatives who were taken across the Atlantic from ports in say Mozambique, Angola, and/or the Congo? It may seem far-fetched, but some of these 5 cM matches are older than from the past couple of hundred years, and some do not even trace unbroken segments of common ancestry (which is evident since some users do not share certain small "matches" with either of their parents).

Also makes some sense since (as a previous poster mentioned) we know from historical records that slaves from East African ports were sent to the Middle East, rather than the Americas.

[Angoliga]

@Lank - Interesting theory, that might very well be the case for some if not all of these distant matches.

The four Kenyans found on GEDmatch include 3 Luos of predominant Bantu ancestry (less than 14% Nilo-Saharan using pDNA) and 1 half Swede/half Luhya (Bantu speaker). The Tanzanian is half Luo and half Hehe (Bantu speaker) and wasn't a match but we shared 1 or 2 distant cousins estimated in the 7th generation range; the same was noticed with the Kenyans.

I still find this theory hard to fathom since the Kenyan matches are from my father's side - I haven't come across any evidence suggesting Central Sudanic speakers penetrated as deep as within the Kenyan Rift Valley. The theory would be more believable if I had Luo or related Bantu ancestry. Moreover, the percentage of my family's Bantu ancestry, even the breakdown of W/U/E Benue Congo (pDNAL), is practically the same as the Bulala - Central Sudanic speakers in Chad. These similarities might suggest their gene pool was the same prior to the major southern Bantu expansions below the Sahel. I might have been more inclined to believe this theory if I found matches within the Middle-East. If the theory is correct and these distant matches are from the Bantu expansion, one would think I'd have a few distant Southern Iranian/Persian/Saudi-Arabian matches from those Zanj Rebellion days (where bantu East-Africans were present) - this slave trade started in the 7th century, surely over the span of 12 centuries of East-African slaves in this region there'd be a few detected IBS matches but that's not the case atm. Or perhaps Middle-Easterns are drastically under-represented; the higher resolution of DNA users in the west might be the culprit but then again why these detected matches from islands - surely there's gotta be more DNA users of Middle-Eastern ancestry than from people of Mauritian, Puerto Rican or Cuban ancestry -- some of these matches genealogical ancestry is exclusively from these islands.

Even if my parent's ethnicity was related to the bantu expansion, it still seems a bit far fetched that 7+cM matches in the new world would be the result of Bantu migrations that occurred thousands of years ago. Especially when the odds of detecting relatives past 6th cousin are typically less than 2% https://www.familytreedna.com/learn/...finder-detect/ With all this considered, who really knows though.

Here's a paper titled The mitochondrial DNA heritage of the Baganda, Lugbara and Acholi from Uganda - Thesis (Ph.D. (Biochemistry))--North-West University South Africa, 2010 - it was written by a Ugandan named Dan Isabirye. The theory of a genetic connection through slavery is stated as a possibility but not given as the only plausible reason for mtDNA matches due to scanty historical records : http://dspace.nwu.ac.za/handle/10394/4221

6.6 (Pg 129) - The clustering of sequences of the Baganda, Lugbara and Acholi with sequences of individuals from Dominican Republic and the Island of Hispaniola, demonstrated that there was a possibility of slave trade involving Ugandans being shipped into America by some means. Since there is no historical account of slave trade directly from Uganda to America and since it was the Arabs, Afro-Arabs and Egyptians who penetrated the interior of Uganda to deal in slavery (Ssekamwa, 1994; Were and Wilson, 1984), it is probable that the Arabs, Afro-Arabs or Egyptians sold some of the slaves to America. Alternatively, it could be that there was some undetectable gene flow from Uganda to certain countries in Africa and thereafter to America thus contributing to the transatlantic slave trade. Concrete evidence for this is however unavailable.

Related to Ugandan mtDNA, I found an African-American 23andMe user with my mother's L3x2b haplogroup. Any theories on how she inherited it?- this subclade is confined to East-Africa (more specifically the horn).

In reply to your statement: "Also makes some sense since (as a previous poster mentioned) we know from historical records that slaves from East African ports were sent to the Middle East, rather than the Americas."

Again, no one's refuting the Middle-East as the dominant destination for slaves throughout the East-African Slave trade.
On the contrary to what we know from historical records, the link from my last post, entitled "The Cuban Slave Trade - 1790-1843", provides a historical record of the amount of ships and slaves that departed from East-African ports (chart, pg 82). Did you even glance at it? Lol - I find my East-African brethren, more often than not, disregard the possibility of even the slightest amount of East-Africans being taken to Americas. I'm not singling you out, to literally every uncle/aunt I've mentioned this -- the response is usually the same. Even the Kenyan match whose mother has over 20+ matches with +7cM detections, most of which have English and Spanish match surnames - he doesn't seem the least interested to correspond on the matter. There's more records of slaves being taken from as far as Lake Malawi to the Swahili coast, that's a distance in the range of 1500km, why are we surprised the same trade took place in other directions from Mombasa and Zanzibar -- what would have impeded them from trading these slaves to the Portuguese and the Spanish along coastal ports in Mozambique? Especially with increased returns following heightened demand from blocked off trade after the Act of 1807.

The only real debate is the quantity of East-African slaves that were sent to the Americas - no one's deluding themselves by saying it compared on the scale of Atlantic slave trade.

[Lank]

@
I still find this theory hard to fathom since the Kenyan matches are from my father's side - I haven't come across any evidence suggesting Central Sudanic speakers penetrated as deep as within the Kenyan Rift Valley. The theory would be more believable if I had Luo or related Bantu ancestry. Moreover, the percentage of my family's Bantu ancestry, even the breakdown of W/U/E Benue Congo (pDNAL), is practically the same as the Bulala - Central Sudanic speakers in Chad. These similarities might suggest their gene pool was the same prior to the major southern Bantu expansions below the Sahel. I might have been more inclined to believe this theory if I found matches within the Middle-East. If the theory is correct and these distant matches are from the Bantu expansion, one would think I'd have a few distant Southern Iranian/Persian/Saudi-Arabian matches from those Zanj Rebellion days (where bantu East-Africans were present) - this slave trade started in the 7th century, surely over the span of 12 centuries of East-African slaves in this region there'd be a few detected IBS matches but that's not the case atm. Or perhaps Middle-Easterns are drastically under-represented; the higher resolution of DNA users in the west might be the culprit but then again why these detected matches from islands - surely there's gotta be more DNA users of Middle-Eastern ancestry than from people of Mauritian, Puerto Rican or Cuban ancestry -- some of these matches genealogical ancestry is exclusively from these islands.

I think Middle Eastern (Arab Muslim specifically) underrepresentation is an important factor. Otherwise, wouldn't Bantu speakers be expected to come up with more Middle Eastern matches? From what I've seen, there are actually relatively large numbers of Puerto Rican and Cuban members.

Related to Ugandan mtDNA, I found an African-American 23andMe user with my mother's L3x2b haplogroup. Any theories on how she inherited it?- this subclade is confined to East-Africa (more specifically the horn).

L3x2b is not really related to the Horn. Hirbo's massive East Africa study, which includes a good number of Kenyans/Tanzanians with significant Cushitic ancestry (including some Burji/Konso with high L3x), only L3x2a was found. Another study sampled southern Ethiopians (including Dawro, Ongota) and found lots of L3x2a, no L3x2b. Same as the Ethiopian caveman Mota, and my paternal grandmother. L3x2b has been found in Algeria.

I don't know how your mtDNA ended up in the New World. As I'm sure you know, Nilo-Saharans (and Central Sudanics) are found as far as Cameroon.

In reply to your statement: "Also makes some sense since (as a previous poster mentioned) we know from historical records that slaves from East African ports were sent to the Middle East, rather than the Americas."

Again, no one's refuting the Middle-East as the dominant destination for slaves throughout the East-African Slave trade.
On the contrary to what we know from historical records, the link from my last post, entitled "The Cuban Slave Trade - 1790-1843", provides a historical record of the amount of ships and slaves that departed from East-African ports (chart, pg 82). Did you even glance at it? Lol - I find my East-African brethren, more often than not, disregard the possibility of even the slightest amount of East-Africans being taken to Americas. I'm not singling you out, to literally every uncle/aunt I've mentioned this -- the response is usually the same. Even the Kenyan match whose mother has over 20+ matches with +7cM detections, most of which have English and Spanish match surnames - he doesn't seem the least interested to correspond on the matter. There's more records of slaves being taken from as far as Lake Malawi to the Swahili coast, that's a distance in the range of 1500km, why are we surprised the same trade took place in other directions from Mombasa and Zanzibar -- what would have impeded them from trading these slaves to the Portuguese and the Spanish along coastal ports in Mozambique? Especially with increased returns following heightened demand from blocked off trade after the Act of 1807.

The only real debate is the quantity of East-African slaves that were sent to the Americas - no one's deluding themselves by saying it compared on the scale of Atlantic slave trade.

I did mention ports in Mozambique, though. :p

If you look at this interactive map, a huge number of slave ships are shown departing from modern-day Angola. Especially from what was the Kingdom of Kongo. Note also that a very large proportion of these went to South America. The fact that you descend from ethnicities not typically associated with the Atlantic slave trade also has to be weighed against the sheer number of slaves coming from those western ports (and the fact that you do have a notable albeit minor Bantu affinity, along with the matches you mentioned). On the eastern coasts, there is a smaller number of ships departing, mainly from Mozambique and Madagascar. But I'm not sure this route is more likely if we look at a map of Central Sudanic speakers and compare distances to the Kingdom of Kongo and Mozambique. Especially if we accept that the matches may be an indirect result of Bantu speakers being captured.

[Morci]

Thanks for sharing Morci! Care to share the details of your East-African matches (ie. estimated relation, size of shared segments)

Thx!

They were all anonymous in countries of ancestry, but I think they were around 5cM matches.