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The genetic legacy of African Americans from Catoctin Furnace
The full paper I will discuss in this post is this one: The genetic legacy of African Americans from Catoctin Furnace 2023 Science 381 6657 eade4995
The list of authors is rather long, but I feel compelled to list all of the authors.
Harney, Éadaoin , Micheletti, Steven , Bruwelheide, Karin S. , Freyman, William A. Bryc, Katarzyna , Akbari, Ali , Jewett, Ethan , Comer, Elizabeth , Gates, Henry Louis , Heywood, Linda , Thornton, John , Curry, Roslyn , Esselmann, Samantha Ancona , Barca, Kathryn G. , Sedig, Jakob , Sirak, Kendra , Olalde, Iñigo , Adamski, Nicole , Bernardos, Rebecca , Broomandkhoshbacht, Nasreen , Ferry, Matthew , Qiu, Lijun , Stewardson, Kristin , Workman, J. Noah , Zalzala, Fatma , Mallick, Shop , Micco, Adam , Mah, Matthew , Zhang, Zhao , 23andMe Research Team† , Rohland, Nadin , Mountain, Joanna L. , Owsley, Douglas W. , Reich, David , Aslibekyan, Stella , Auton, Adam , Babalola, Elizabeth , Bell, Robert K. , Bielenberg, Jessica , Bullis, Emily , Coker, Daniella , Cuellar Partida, Gabriel , Dhamija, Devika , Das, Sayantan , Elson, Sarah L. , Filshtein, Teresa , Fletez-Brant, Kipper , Fontanillas, Pierre , Heilbron, Karl , Hicks, Barry , Hinds, David A. , Jiang, Yunxuan , Kukar, Katelyn , Lin, Keng-Han , Lowe, Maya , McCreight, Jey , McIntyre, Matthew H. , Moreno, Meghan E. , Nandakumar, Priyanka , Noblin, Elizabeth S. , O’Connell, Jared , Petrakovitz, Aaron A. , Poznik, G. David , Schumacher, Morgan , Shastri, Anjali J. , Shelton, Janie F. , Shi, Jingchunzi , Shringarpure, Suyash , Tran, Vinh , Tung, Joyce Y. , Wang, Xin , Wang, Wei , Weldon, Catherine H. , Wilton, Peter , Hernandez, Alejandro , Wong, Corinna D. , Tchakouté, Christophe Toukam , Fitch, Alison , Reynoso, Alexandra , Granka, Julie M. , Su, Qiaojuan Jane , Kwong, Alan , Eriksson, Nicholas , Nguyen, Dominique T. , Llamas, Bianca A. , Tat, Susana A.
A news item which may be more accessible to non-scientists which may be open sourced, from Nature, , describing the paper is here: Ancient DNA reveals the living descendants of enslaved people through 23andMe
The subtitle of the Nature news item:
A landmark genomic study raises the possibility that many more people could find links to distant ancestors through genetic analysis.
A photo from the Nature article is moving:
?as=webp
The caption:
Facial reconstructions based on the excavated remains of enslaved African Americans who worked at the Catoctin Furnace iron forge in Maryland in the late eighteenth or early nineteenth centuries.Credit: Getty/Washington Post
The structured abstract of the full paper however seems not to be filled with arcane jargon, and probably suffices:
Structured Abstract
INTRODUCTION
Genetic analysis of historical individuals has the potential to help restore knowledge of people whose stories were omitted from written records. During the late 18th and early 19th centuries, Catoctin Furnace in Maryland relied on a workforce of enslaved individuals to operate the iron furnace and carry out domestic and agricultural tasks. Despite the role that Catoctin Furnace played in early US history (including supplying munitions during the Revolutionary War), relatively little is known about the African Americans who labored there or their descendants compared with the furnace’s later, predominantly white workforce.
RATIONALE
We produced genome-wide data for 27 individuals buried in the Catoctin Furnace African American Cemetery and compared them to ~9.3 million consenting research participants genotyped by 23andMe, Inc., to address the following questions: (i) How were the Catoctin individuals related to each other? (ii) What were the sources of their African and European ancestry? (iii) Where in the US do their genetic relatives live today, including their direct descendants? (iv) What can their genomes reveal about their health?
RESULTS
We identified five genetic families, consisting of biological mothers, children, and siblings, among the Catoctin individuals. In most cases, biological family members were buried in close proximity.
All but one of the Catoctin individuals had primarily African ancestry, with variable amounts of European ancestry. To learn more about their ancestry, we developed an approach to detect identical-by-descent segments of the genome shared between the Catoctin individuals and 23andMe research participants. Identical-by-descent segments of DNA are shared by two or more people because they have been inherited from a recent common ancestor. We identified 41,799 close and distant relatives of the Catoctin individuals among 23andMe research participants. Within Africa, we found the highest rates of genetic sharing between Catoctin individuals and research participants who self-identified as belonging to the Wolof or Kongo ethnolinguistic groups. Within Europe, we observed the highest rates of genetic sharing with research participants that have ties to Great Britain and Ireland.
Within the US, participants from the South showed elevated rates of sharing, largely reflecting distant connections to 23andMe research participants with sub-Saharan African ancestry (possibly tracing back to shared common ancestors in Africa). When we considered genetic relatives who share the most identical DNA with the Catoctin individuals, we observed the highest rates of sharing in Maryland, suggesting that at least some descendants stayed in the region after the furnace’s transition away from enslaved and paid African American labor.
Finally, we found that some of the Catoctin individuals carried risk factors for sickle cell anemia and glucose-6-phosphate dehydrogenase deficiency, genetic diseases that are common in African Americans today.
CONCLUSION
These results demonstrate the power of joint analysis of DNA from historical individuals and the extremely large datasets generated through direct-to-consumer ancestry testing, and they serve as a model for obtaining direct insights into the genome-wide genetic ancestry of enslaved people in the historical US.
INTRODUCTION
Genetic analysis of historical individuals has the potential to help restore knowledge of people whose stories were omitted from written records. During the late 18th and early 19th centuries, Catoctin Furnace in Maryland relied on a workforce of enslaved individuals to operate the iron furnace and carry out domestic and agricultural tasks. Despite the role that Catoctin Furnace played in early US history (including supplying munitions during the Revolutionary War), relatively little is known about the African Americans who labored there or their descendants compared with the furnace’s later, predominantly white workforce.
RATIONALE
We produced genome-wide data for 27 individuals buried in the Catoctin Furnace African American Cemetery and compared them to ~9.3 million consenting research participants genotyped by 23andMe, Inc., to address the following questions: (i) How were the Catoctin individuals related to each other? (ii) What were the sources of their African and European ancestry? (iii) Where in the US do their genetic relatives live today, including their direct descendants? (iv) What can their genomes reveal about their health?
RESULTS
We identified five genetic families, consisting of biological mothers, children, and siblings, among the Catoctin individuals. In most cases, biological family members were buried in close proximity.
All but one of the Catoctin individuals had primarily African ancestry, with variable amounts of European ancestry. To learn more about their ancestry, we developed an approach to detect identical-by-descent segments of the genome shared between the Catoctin individuals and 23andMe research participants. Identical-by-descent segments of DNA are shared by two or more people because they have been inherited from a recent common ancestor. We identified 41,799 close and distant relatives of the Catoctin individuals among 23andMe research participants. Within Africa, we found the highest rates of genetic sharing between Catoctin individuals and research participants who self-identified as belonging to the Wolof or Kongo ethnolinguistic groups. Within Europe, we observed the highest rates of genetic sharing with research participants that have ties to Great Britain and Ireland.
Within the US, participants from the South showed elevated rates of sharing, largely reflecting distant connections to 23andMe research participants with sub-Saharan African ancestry (possibly tracing back to shared common ancestors in Africa). When we considered genetic relatives who share the most identical DNA with the Catoctin individuals, we observed the highest rates of sharing in Maryland, suggesting that at least some descendants stayed in the region after the furnace’s transition away from enslaved and paid African American labor.
Finally, we found that some of the Catoctin individuals carried risk factors for sickle cell anemia and glucose-6-phosphate dehydrogenase deficiency, genetic diseases that are common in African Americans today.
CONCLUSION
These results demonstrate the power of joint analysis of DNA from historical individuals and the extremely large datasets generated through direct-to-consumer ancestry testing, and they serve as a model for obtaining direct insights into the genome-wide genetic ancestry of enslaved people in the historical US.
The opening text of the full paper also seems accessible:
The vast majority of the ~45 million self-identified Black and/or African American individuals living in the United States descend from ~456,600 enslaved Africans who were forcibly transported to the US from Africa during the transatlantic slave trade between 1501 and 1867 (1, 2). However, African Americans often have little information about these ancestors or their African origins owing to a history of inhumane treatment of the enslaved and their descendants, which included marginalization and the obfuscation of family histories (3). Here, we demonstrate that, when combined with genome-wide data from a sufficiently large and diverse genetic database, DNA from historical individuals provides a means for restoring knowledge of familial connections between contemporary peoples and their historical relatives. Specifically, we report on the DNA of enslaved and free African Americans from Catoctin Furnace, Maryland, who lived, worked, died, and were buried there in the late 18th and early 19th centuries.
As early as December 1768, a tract of land was acquired for the purposes of building an iron works at the foot of Catoctin Mountain near present-day Thurmont, Maryland (4). The furnace was in blast by 1776, producing pig iron, tools, household items, and munitions used during the Revolutionary War. At least 271 enslaved and an unknown number of free African Americans worked at Catoctin, within and outside the furnace, as ore miners, colliers, forgemen, fillers, teamsters, and woodcutters, as well as in domestic and agrarian roles in the furnace owners’ households and plantations (5). In the second quarter of the 19th century, the furnace’s labor force switched primarily to wage labor and a predominantly white workforce (6). Gradually, the contributions of African Americans in this early industrial complex were largely forgotten. The Catoctin Furnace African American Cemetery, near an old ore pit, was excavated in 1979–1980 in advance of highway construction (Fig. 1A) (7–10). The Maryland State Highway Administration transferred stewardship of the recovered remains of deceased humans to the Smithsonian Institution, where curator J. Lawrence Angel conducted preliminary forensic anthropological investigations (11)...
As early as December 1768, a tract of land was acquired for the purposes of building an iron works at the foot of Catoctin Mountain near present-day Thurmont, Maryland (4). The furnace was in blast by 1776, producing pig iron, tools, household items, and munitions used during the Revolutionary War. At least 271 enslaved and an unknown number of free African Americans worked at Catoctin, within and outside the furnace, as ore miners, colliers, forgemen, fillers, teamsters, and woodcutters, as well as in domestic and agrarian roles in the furnace owners’ households and plantations (5). In the second quarter of the 19th century, the furnace’s labor force switched primarily to wage labor and a predominantly white workforce (6). Gradually, the contributions of African Americans in this early industrial complex were largely forgotten. The Catoctin Furnace African American Cemetery, near an old ore pit, was excavated in 1979–1980 in advance of highway construction (Fig. 1A) (7–10). The Maryland State Highway Administration transferred stewardship of the recovered remains of deceased humans to the Smithsonian Institution, where curator J. Lawrence Angel conducted preliminary forensic anthropological investigations (11)...
A graphic of the layout of the graves and relationships between the families:
The caption:
Fig. 1. Burial context, genetic kinship, and ancestry of Catoctin individuals.
(A) Map showing the location of Catoctin Furnace and burials within the cemetery. Burial locations of the five genetic families are circled. The rectangle in the upper right shows a portion of the cemetery with unexcavated burials identified through ground-penetrating radar. [Map adapted from (12), prepared by Robert Wanner] (B) Individuals, labeled according to burial ID, are grouped into families on the basis of genetic relationships. Genetic sex, mt haplogroups, and Y haplogroups are indicated by marker shape, fill color, and outline color, respectively. The type of genetic relationship is indicated by connector line style. Marker fill pattern indicates individuals with one or more copies of an allele associated with sickle cell anemia or G6PD deficiency. (C) Ancestry proportions assigned to each individual from representative African (YRI), European (GBR), and Indigenous American (Pima) populations drawn from the public dataset according to the qpAdm software. Error bars indicate one standard error. Asterisks (*) indicate cases where damage-restricted data were analyzed. Hash symbols (#) and plus signs (+) indicate models with P < 0.01 or ancestry proportion estimates that fall more than three standard errors outside the range of 0 to 1, respectively.
(A) Map showing the location of Catoctin Furnace and burials within the cemetery. Burial locations of the five genetic families are circled. The rectangle in the upper right shows a portion of the cemetery with unexcavated burials identified through ground-penetrating radar. [Map adapted from (12), prepared by Robert Wanner] (B) Individuals, labeled according to burial ID, are grouped into families on the basis of genetic relationships. Genetic sex, mt haplogroups, and Y haplogroups are indicated by marker shape, fill color, and outline color, respectively. The type of genetic relationship is indicated by connector line style. Marker fill pattern indicates individuals with one or more copies of an allele associated with sickle cell anemia or G6PD deficiency. (C) Ancestry proportions assigned to each individual from representative African (YRI), European (GBR), and Indigenous American (Pima) populations drawn from the public dataset according to the qpAdm software. Error bars indicate one standard error. Asterisks (*) indicate cases where damage-restricted data were analyzed. Hash symbols (#) and plus signs (+) indicate models with P < 0.01 or ancestry proportion estimates that fall more than three standard errors outside the range of 0 to 1, respectively.
More text:
...The Catoctin Furnace Historical Society, Inc. (CFHS), was initially founded to save the Catoctin Furnace village and its archaeological and architectural heritage from this highway construction (4). In recent years, its mission has expanded to include restorative justice, highlighting the critical role that enslaved and free African Americans played in the furnace’s history and in the growth of industrial wealth and power in the young United States. In 2015, a grant from the Maryland Heritage Areas Authority supported further scientific analysis of individuals buried in the cemetery. The first phase of the project involved historical documentary research and osteological reanalysis that refined previous assessments of demography and bone and dental pathology, with testing for stable carbon and nitrogen isotopes and trace elements to shed light on the life histories of the individuals (12)...
More text on the consent of modern African Americans for genetic comparison with the enslaved human beings:
...We recovered genome-wide aDNA from all 27 of the Catoctin individuals who were selected for sampling, targeting ~1.2 million single-nucleotide polymorphisms (SNPs) using a capture-based approach (23–26), which we combined with imputation to further increase the amount of available genetic information (table S1). By comparing the DNA of the Catoctin individuals with genotype data from 9,255,493 participants in the 23andMe cohort, all of whom consented to participate in research, we were able to learn about their biogeographic ancestries and genetic relationships with one another and to provide insight into their genetic legacy by identifying identical-by-descent (IBD) connections with living relatives...
The important ethics statement:
This research analyzed data from deceased individuals who were unable to directly consent to participate in this study, as well as from millions of research participants (including those genotyped by 23andMe) who actively consented to participate in research. The ties between present-day African Americans, their ancestors within the US, and their ancestors in Africa were forcibly severed by the transatlantic slave trade, the centuries-long institution of slavery, and generational systemic racist practices that have endured after the abolition of race-based slavery (27), as illustrated by Frederick Douglass’s famous words: “Genealogical trees do not flourish among slaves” (28). Our objective is to contribute to the restoration of memories of a past community whose legacy was intentionally obscured and to create an avenue for living people to learn about their ancestors. We followed guidelines for the ethical analysis of the DNA of historical and living people (29, 30), including consultation with stakeholder groups, as emphasized in recent discussions on the future of studies involving the remains of African Americans (31–35). On the basis of interactions with stakeholders, we believe there is interest among African Americans and the public to harness aDNA to learn about historical connections to people who lived in the past and to leverage this technology to develop accurate methods to identify genetic relationships, many of which were previously unknown. Equally important is the need to communicate the results of these analyses with descendants and others in a sensitive and accurate manner...
An illustrative graphic:
The caption:
Fig. 3. Examples of chronological and genealogical distance between historical individuals and research participants.
(A) A timeline showing the years in which the African American Cemetery at Catoctin Furnace was active and a histogram of birth years of research participants who share IBD with Catoctin individuals (table S23). (B) Examples of relationships that could be shared between individuals who were born five generations apart, with varying degrees of genetic separation. Median amount of IBD is reported for pairs of present-day and historical individuals (with 2× coverage) (table S7).
(A) A timeline showing the years in which the African American Cemetery at Catoctin Furnace was active and a histogram of birth years of research participants who share IBD with Catoctin individuals (table S23). (B) Examples of relationships that could be shared between individuals who were born five generations apart, with varying degrees of genetic separation. Median amount of IBD is reported for pairs of present-day and historical individuals (with 2× coverage) (table S7).
The paper does touch on many challenging ethical considerations as I see it, but I support this work, detailing the lives involved in human slavery, a stain on American history that can never be erased.
The full paper has fascinating details.
Have a great weekend.