History, Mystery and DNA Analysis
History, Mystery and DNA Analysis
The concept of identity, who we are and where we come from, has piqued human interest for thousands of years. The study of our origins, and those of our predecessors, is known as genealogy.
"Genealogy involves finding the relationships in your family and discovering who your ancestors are by using historical records and increasingly other resources to build up a story of your family," Else Churchill, a genealogist at the Society of Genealogists in London, explains.
Historically, it was considered to be a field of research concerned with aristocratic members of society – families with wealth, possessions, land or titles that could be claimed by subsequent generations. This viewpoint shifted gradually over time, Churchill emphasizes, as an antiquarian interest in family and community history evolved.
Birth, death and census records, diary entries, alumni associations, bar mitzvah records and oral histories are just some of the resources used by genealogists to trace lineages. The latter part of the 20th century saw the rise of computers, the internet and the digitalization of records – technological advances that bolstered the field by increasing access to such information. At a similar time, science was entering a revolutionary period – the "genomic era" – whereby advances in DNA analysis technology made it possible to sequence and analyze DNA quickly and at a low-cost. This progress gifted genealogists with a new, biological tool: DNA – the thread of nucleotides that tie us to our predecessors. And so, genetic genealogy, whereby DNA analysis is used to complement traditional genealogy methods, was born. It quickly became commercialized, and the first direct-to-consumer (DTC) genetic ancestry test was marketed in 2000.1 By 2016, approximately 246 companies were offering online DNA tests, 30% of which were ancestry services, of some description.2
DNA analysis is a complement to the field, but it is not the whole picture, Churchill emphasizes: "Many people now might start their genealogy investigations with a DNA test but realize that to find details and more information they will have to use traditional methods too."
An incentive to using DNA for genealogical analyses is that it stands the test of time. Allentof et al calculated the half-life of DNA to be 521 years.3 This means that after a period of 521 years, half of the bonds between the nucleotides of a DNA double helix would break. Fast-forward another 521 years, and half of the remaining bonds in that sample would have broken, and so on. Based on optimal preservation conditions, it would take 6.8 million years for every single bond in the DNA to break. New capabilities to extract "ancient" DNA are enabling scientists to understand the history of our planet and its inhabitants. Earlier this year, palaeogenetecists successfully extracted and sequenced DNA from a Siberian mammoth's molar. The DNA was estimated to be 1.2 million-years-old.
In terms of human genealogy research, the longevity of DNA means that, where the paper trail of history may not survive, DNA often will. It is helping academics and scholars to study and clarify our understanding of historical events in human history through bioarchaeological research. The most recent case study centers on the ill-fated Franklin Expedition.4
The Franklin Expedition
In April 1845, British Royal Navy officer and explorer Captain Sir John Franklin departed from the shores of England with a crew of 129 men aboard two ships: HMS Erebus and HMS Terror. The explorers were assigned to search for a Northwest passage in the grueling conditions of the Canadian Arctic. In the years that followed, neither Erebus nor Terror returned to Britain.
In 1859, a rescue mission led by Francis Leopold McClintock was ordered by Franklin's wife. The team discovered a note in a cairn near Victory Point on the west coast of King William Island; it provided crucial information about what had happened to the voyagers. Early in the expedition (September 1846), the vessels became icebound in Victoria Strait, off the Northwest coast of King William Island, Nunavut. After being stranded for 18 months, the 105 surviving members of the crew chose to abandon the ships in late April 1848 as a last-ditch attempt at survival. By this point, Franklin himself had already passed away.
Sadly, their efforts were futile; every single member of the Franklin expedition would perish. Captured by the catastrophic event, historians, archaeologists and specialist investigators have puzzled over the explicit details of how and when the men died. "Much has been written about the expedition, from various perspectives, but we still have a limited understanding of what exactly happened," explains Canadian archaeologist Douglas Stenton, former director of Heritage for the Government of Nunavut Department of Culture and Heritage. "Various explanations for the expedition's fatal outcome have been advanced (e.g., lead poisoning, scurvy, botulism and tuberculosis, etc.), but the underlying causes are not well understood."
Skeletal remains have been found that were either known or presumed to belong to expedition members across a number of locations along the Western and Southern coasts of King William Island. While analysis of the skeletons can provide valuable insights, what remains elusive is the identities of the men; and so, 176 years after the ships left British shores, the interest in the expedition endures. "We know that at Erebus Bay, for example, at least 23 men died," Stenton says. What exactly happened there? Who were they? How many were officers, able seamen, or Royal Marines? "If that [information] was known, how might it affect current interpretations?" says Stenton.
Genetic genealogy brought a breakthrough in the Franklin expedition post-mortem in 2021. A small collection of bones discovered at Erebus Bay, on the Southwest coast of King William Island – approximately 80 km from where the ships became trapped – were identified as belonging to Warrant Officer John Gregory, an engineer aboard HMS Erebus, thanks to a DNA sample provided by a descendent.
The search commences
"The [King William Island] site has a fascinating history," explains Stenton. In 1859, the McClintock search expedition discovered the remains of two men in a small boat that had been hauled on a sledge by Franklin's men. They left the remains at the site, which were later discovered by Inuit. In 1879, a search expedition led by Frederick Schwatka rediscovered the site. The boat had been completely dismantled by Inuit to repurpose the wood and metal. Schwatka gathered the human remains together, buried them and erected a commemorative cairn over the grave. "At an unknown time, but likely in the 19th century, the cairn was dismantled, a few of the bones in the grave were displaced and the location of the grave became unknown," Stenton describes. "The site was rediscovered in 1993 by Barry Ranford and documented in 1994. In 1997, three displaced bones found on the surface were placed within a small cairn."
Stenton and his colleague Robert Park investigated the site in 2013, excavated the grave and collected the bones. They were sent to Trent University for osteological examination by Anne Keenleyside, who analyzed the remains to gather information relating to stature, age, sex and evidence of trauma or pathology. In 2014, the skeletons were returned to King William Island and placed in a new commemorative cairn. Prior to returning the skeletons – in an attempt to identify who the remains belonged to – tooth and bone samples were sent to the Centre for Analytical Services Paleo-DNA Laboratory at Lakehead University for DNA analysis. Researchers in the lab extracted the DNA and performed feasibility tests that helped to determine which types of DNA were available for analysis. A profile was then made for each sample – some Y chromosome DNA (Y-DNA) profiles and all mitochondrial DNA (mtDNA) profiles.
mtDNA refers to our maternal ancestry. It is DNA that lies outside of the nucleus, in our mitochondria – organelles often nicknamed the "powerhouse" of a cell due to their role in energy conversion. mtDNA is passed down through the maternal lineage with very little mutation over time. It can be analyzed from both males and females to establish an unbroken maternal lineage.
Y-DNA, on the other hand, refers to paternal ancestry and is found using the Y-chromosome. "This type of DNA is passed down through the paternal (male) lineage with very little mutation over many generations. A father passes it onto his son," explains Stephen Fratpietro, technical manager at the Centre for Analytical Services Paleo-DNA Laboratory, and second author of the study.
Using the DNA profiles extracted from the samples, the researchers predicted which haplogroup –sometimes known as a "DNA signature" – they belonged to. Haplotypes are a set of markers, be it a combination of alleles or polymorphisms (variants), that are typically inherited together. "Since we now had a database of DNA profiles from the samples and [knew that] these types of DNA are passed on to successive generations, the next step was to find living descendants who would make good candidates for DNA comparison," says Fratpietro. The search commenced and would continue for several years with 16 failed matches.
Finally, a match
In 2019, Jonathan – Joe – Gregory (38) of South Africa received a Facebook message from a cousin living in Canada. "It informed me that researchers [who had found skeletal remains] were reaching out to people around the world asking if they were prepared to submit DNA samples, predominantly from XY chromosome males," he says.
Joe recalls "always having an awareness" that a connection between his family and the Franklin expedition may exist, but it had not been conclusively determined. Genealogical information suggested a five-generation paternal relationship, but would the DNA analysis confirm this?
Joe provided a buccal swab to the team for DNA comparison. Transportation issues, coupled with the disruption caused by the COVID-19 global pandemic, meant the line of communication went quiet for a short while.
Meanwhile in the lab, Fratpietro and team were constructing a Y-chromosome profile from Joe's DNA. This was not an easy feat due to the level of preservation of the samples from the Franklin expedition. Not all of the samples submitted for analysis yielded both mtDNA and Y-DNA for profiling. "A lot [of the samples] only contained mtDNA. In terms of finding living descendants, Y-DNA is easier to trace back to a member of the Franklin Expedition using genealogy because a last name is usually passed on to the male children. Tracing back one’s roots using mtDNA is a bit more complicated since it is traced back though the female lineage," Fratpietro says.
The team found a match of 20 markers from Joe's profile to a 20-marker profile from a sample labeled NgLj-3:34. Based on Joe's lineage information, the researchers hypothesized that the excavated DNA sample belonged to Warrant Officer John Gregory.
The significance of the match had to be verified, and so the profile was compared to a Y-chromosome database to calculate its frequency. In a database of 73,006 other profiles, it was unique, Fratpietro explains: "Additionally, we performed another calculation to determine the kinship index, which is a likelihood ratio of someone being paternally related versus not being paternally related. That index was 47,030 – such a large number that it would indicate strong support that Joe and NgLj-3:34 are 47,030 times more likely to be paternally related than unrelated."
NgLj-3:34 was John Gregory, and Joe Gregory is his great-great-great-grandson.
A twist in the tale
Joe was informed of the news via email, and recalls having to hold on to the edge of his seat as the word "match" appeared in the subject line. “There’s a link now, and we can relate to it on so many levels," he delights.
Stenton, Fratpietro and colleagues sought the services of a professional genealogist in Britain to conduct archival and database research in order to clarify what was known about John Gregory. He was married to Hannah Wilson and they had a son, Edward John Gregory. Prior to the expedition, he worked as an engineer for a marine steam engine firm in Lambeth, London. Based on available records, it would appear that John was hired for the voyage at short-notice and was compensated with an increased salary. In 1845 he wrote to Hannah. In the letter, he spoke of spotting icebergs and whales in Greenland, verifying that the voyage had not yet reached the Canadian Arctic. Hannah never heard from John again.
In 1850, Edward Gregory had a son that bore the same name: Edward John Gregory – the famed British artist that commissioned the Boulters Lock painting. While not mentioned in the study publication, Joe is in possession of several artefacts worn by Edward, including a waist coat and a version of the famed painting.
Artefacts belonging to Edward John Gregory, now in possession of Joe Gregory. Credit: Joe Gregory.
An "important component" of bioarchaeological research
This is just one example of a historical case solved using genetic genealogical methods, and it is likely there will be many more to come in the future. Stenton believes it is a "fascinating approach": "Its potential has been demonstrated in many archaeological contexts, and it has become an important component of bioarchaeological research," he says.
For the Gregory family, the discovery is not an obituary, it is history. They express sheer gratitude to the researchers for unlocking this vital information regarding their families' origin that has been frozen in time.
The researchers encourage any individuals that believe they could be living descendants of members of the expedition to come forward, so that they continue their quest of identifying the voyagers' remains using DNA analysis.
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3. Allentoft ME, Collins M, Harker D, et al. The half-life of DNA in bone: measuring decay kinetics in 158 dated fossils. Proceedings of the Royal Society B: Biological Sciences. 2012;279(1748):4724-4733. doi: 10.1098/rspb.2012.1745.
4. Stenton DR, Fratpietro S, Keenleyside A, Park RW. DNA identification of a sailor from the 1845 Franklin northwest passage expedition. Polar Record. 2021;57:e14. doi: 10.1017/S0032247421000061.