The recent article in The Root by Boston University historians Linda Heywood and John Thornton generated considerable interest in their groundbreaking findings that most American blacks are descended from just 46 ethnic groups and three major regions of Africa.
In a follow-up interview, they explain the process they used to reach their results and the significance of those findings for African Americans in search of their ancestry.
The Root: Your article for The Root described how the majority of African Americans originated with just 46 ethnic groups in Africa from three major regions. What is the significance of those findings?
John Thornton and Linda Heywood: By showing how concentrated the slave trade was, in just a few regions of Atlantic Africa, we can bring more attention to the exact historical processes that caused people to be enslaved. The histories of these areas are fairly well-known among historians specializing in African history, for example, and we can name rulers, outline the course of wars, discover trading patterns and learn about judicial systems in the areas.
We can also see in detail how relations between Africans and Europeans changed over time, and how this, in addition to changes in African politics, resulted in the capture, enslavement and export of some African groups and not others.
TR: What impact does the narrowing of origins have on the efforts of African Americans to trace their origins?
JT and LH: At the present time, DNA results often produce matches with people living in different regions of Africa, some of which never participated in the Atlantic slave trade. We can discount results that point to Cameroon, South Africa or Ethiopia, for example; few or no enslaved Africans from these regions came to North America during the period of the slave trade.
On the other hand, we favor results that indicate Angola, Nigeria or Senegal connections, as these were areas that supplied the majority of slaves to the United States. It will also allow researchers who are seeking to identify populations to target these areas to collect samples, and thus expand the pool of potential African relatives of African Americans.
TR: Is there often a gap between the oral history in families and the actual DNA results of many African Americans?
JT and LH: As far as we're aware, very few African-American families have traditions that point to specific regions of Africa. In fact, in places where such traditions are found, they are usually quite right. We know, for example, of people who have been told their ancestors came from Congo, and sure enough, the DNA established that it was true.
TR: What scientific advances or progress in research enabled you to reach your conclusions? Did you analyze DNA data?
JT and LH: Our research for this article was based on documentary sources, studying the patterns of trading between Africa, Europe and America (especially using the newly expanded Du Bois database), the reconstruction of events in the relevant African regions and notices from the period of the slave trade of the African origins of people who were listed in documents of the time. We also made extensive use of interviews conducted by missionaries with first-generation enslaved Africans.
DNA research has also advanced, largely because of the increase in the number of people being tested. This expanded pool will continue to grow as more research and testing is done.
We only made use of DNA data for our work with Henry Louis Gates Jr. (editor-in-chief of The Root) as consultants for African American Lives, his PBS TV show, and as consultants for AfricanDNA.com. We're not geneticists; we're historians, but we have read scientific papers written by geneticists to understand the general problems.
TR: The mapping and quantifying of the slave routes has been an important advance in recent years. How does that tie into your research?
JT and LH: Certainly one crucial step has been the development of the Trans-Atlantic Slave Trade Database since 1999, which has combined literally thousands of documents on the movement of shipping across the Atlantic and allowed quantitative estimates of the arrivals in America. Over the years many scholars have slogged through inventories and reported their results, which cumulatively have greatly increased our knowledge of origins of Africans held in slavery.
We have also benefited from the publication of missionary documents that were vital to understanding this. The publication of Christian Georg Andreas Oldendorp's German manuscript in 2001 was absolutely vital to this article.
TR: A number of DNA services offer to pinpoint your African origins. How accurate are such results? Is there enough data to justify these results?
JT and LH: Initially the results were uneven. We combined DNA results with other data, such as family history in America and shipping records, to try to get over ambiguities in the results. Many users of the services found that they had potential ancestors in more than one area in Africa, and at times these contradictions could be limited or resolved by these methods. But for only a few could the results be considered really definitive.
Linda [Heywood]'s result was one of the more secure ones, because of the peculiarities of her ancestral group. Her mitochondrial DNA test showed that she matched people today who are called Fulbe, in the Futa Jallon part of Guinea Bissau. We know historically that the Fulbe of Futa Jallon, along with those of Futa Tooro, undertook long migrations in the 16th through 19th centuries from the coast of West Africa (Senegal and Guinea) all the way to modern-day Chad and Cameroon.
Linda had a number of matches in the Fulbe homeland, but also with people not identified as Fulbe but clearly living on their migration path. Since she was dealing with female ancestors, through the mitochondrial DNA these problems could be understood by thinking of marriages by Fulbe women to non-Fulbe men, whose descendants would not claim Fulbe origin.
In Linda's case, and some others like hers, yes. But for others, more data will certainly help. There have still not been many Africans tested, and many of those who have been tested do not come from the core regions of the slave trade. For example, Cameroon is heavily sampled, thanks to a variety of projects often not related to the study of the slave trade, whereas Angola is very poorly sampled. Yet Cameroon supplied very few people to North America, and Angola supplied over one-quarter of the African-American ancestral population.
TR: What areas of African history are you exploring at this time?
JT and LH: We both have continuing projects that investigate the history of the African regions that supplied the slave trade. Linda is working on a biography of Queen Njinga, the 17th-century Angolan queen who fought the Portuguese, and Africans in Brazil. John is working on the history of the Kingdom of Kongo as well as other parts in Atlantic Africa and some of the American regions where these Africans went.
Joel Dreyfuss is managing editor of The Root.