The revelation of the mother

In a world first, a portion of an individual’s genome has been reconstructed from those of their living descendants, a feat that sheds light on story of the first person of African descent to settle in Iceland.

Denmark bought the Caribbean island of St. Croix from the French in 1733, and along with other islands it became part of the Danish West Indies, now the US Virgin Islands. Like so many other colonial holdings in the Caribbean, it was turned to sugar production on the backs of slaves.

Out of the millions taken from the west coast of Africa between the Seventeenth and Nineteenth centuries, at least 45,000 were sent to Danish West Indies. In 1784, on a St. Croix sugar plantation, a house slave called Emilia Regina gave birth to a boy named Hans Jonatan.

Hans’ father, according to church records, was a white man called Gram, most likely the secretary to the plantation owner, Heinrich Ludvig Ernst von Schimmelmann. Little more is known. Emilia Regina is thought to have been born on St. Croix, but exactly where in Africa her family originated was never recorded.

The Schimmelmann business suffered in the 1780s and the family, along with Hans and his mother, returned to Copenhagen. While Denmark invested in slaves in their colonial territories, the practice was illegal at home, so Hans declared himself a free man. Eventually his legal status came into question, and in 1802 a court ruled he be returned to St. Croix. As a slave.

Hans turned out to be a resourceful young chap, however.  Somehow, he escaped the Danish authorities and is next recorded as living in Djúpivogur, in Iceland, in 1805. In 1820 he married a local woman, had two children and lived the life of a farmer, and genuinely free man, until his death in 1827.

Iceland in the Nineteenth century only had a population of roughly 50,000. Migration was extremely rare and came mostly from Denmark, so Hans’ appearance would have caused quite a stir. Importantly, he was the only source of recent African chromosomal material in the Icelandic genepool.

New research published in Nature Genetics now capitalises on this fact. An international team led by Anuradha Jagadeesan, Kári Stefánsson and Agnar Helgason of the Icelandic company deCODE Genetics, have combined genetic investigation and historical sources to try to piece together Hans’ maternal haplotype, the DNA he received from his mother.

The scientists examined the DNA of 182 of Hans’ living descendants. Twenty had their entire genome sequenced, while the rest were genotyped using single-nucleotide polymorphisms (SNPs), gene variants that pass down the generations largely unchanged.

Using specialist software designed to work out ancestry using small DNA fragments, and a variety of genetic maps, such as HapMap and the 1000 Genomes Project, the team found hundreds of chromosome fragments that were of African origin. In doing so they were able to piece together 38% of Hans’ maternal genome.

“To our knowledge,” the authors write, “this study demonstrates the first use of genotype data from contemporary individuals, along with information about their genealogical relationships, to reconstruct a sizeable portion of the genome from a single ancestor born more than 200 years ago.”

They also confirmed that Hans’ father was European and have come tantalisingly close to identifying his mother’s African origin. The reconstructed maternal genome suggests that Emilia’s family probably came from Benin, Nigeria or Cameroon, including inconclusive hints pointing to Benin’s Yoruba people.

The research shows the ways that genetics can help us to better understand people of historical interest, but also holds promise for medical genetic research, and understanding evolutionary forces such as recombination and mutation.

Beyond that, as the authors note, “it represents an uplifting story of a resourceful refugee from the Danish transatlantic slave trade, who was able to prosper in a culturally homogeneous and insular community of early-nineteenth-century Icelanders.”