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Unhackable Icelanders know their family tree;
Hans Jonatan’s grandson (below)–
quantum
his mother. To do so, the team
comms for all took DNA samples from 182 of his
descendants, starting with some
THERE’S a new way to make sure of his great-great-grandchildren.
quantum networks are secure. deCODE could rebuild parts of
Theoretically, messages sent via Jonatan’s genome because Iceland
quantum networks are protected by has kept careful records of family
the laws of quantum mechanics. This trees since it was first colonised
is because any attempt to intercept more than 1000 years ago. More
information sent between two parties recently, deCODE built a database
will disturb its fragile quantum state, of DNA from 150,000 Icelanders.
revealing the eavesdropper. One way ARNALDUR HALLDORSSON/BLOOMBERG VIA GETTY Equally crucially, Jonatan was
to check a quantum line is secure the first inhabitant of Iceland with
involves solving an equation called a African heritage.“There was no
Bell inequality – if the result exceeds African ancestry in Iceland, apart
a certain number, there is a limit to from Hans Jonatan, prior to
how much information a spy can around 1920,”says Stefánsson.
extract without being detected. The DNA Jonatan got from his
But this is only true for messages
sent between two points. On a more DNAofmanfrom1827 mother was distinct from that of
other Icelanders, which was
complex network, the Bell inequality almost entirely of European
doesn’t apply. That is roughly because built from living relatives origin. Its distinctness allowed
quantum hackers can gain a little bit deCODE to track bits of African
of information from each part of the IT’S not bringing back the dead, a fishing town in east Iceland. DNA from Jonatan’s genome
network and then piece it together. but it’s close. A man’s genome has “He was the first black man to through his descendants and
One solution would be to create been partially pieced together set foot on Icelandic soil and was reassemble as many as possible.
point-to-point connections between from fragments of his DNA found received with open arms,”says deCODE ultimately rebuilt
everyone on a quantum network, in hundreds of his modern-day Kári Stefánsson of deCODE 38 per cent of the DNA in Regina’s
but that is hardly practical, says Ciarán descendants. It is the first time a Genetics in Reykjavik, Iceland. chromosomes, equivalent to
Lee at University College London. dead person’s genome has been Jonatan became a merchant 19 per cent of Jonatan’s genome
Lee and his colleague Matty Hoban reconstructed without DNA and farmer. He had two surviving (Nature Genetics, doi.org/cjbj).
at the University of Oxford have found extracted from their remains. children with his Icelandic wife, By comparing Regina’s rebuilt
a better way. They have shown that The person is Hans Jonatan, Katrín Antoníusdóttir. DNA to African samples, they
a more complex version of the Bell an icon in Iceland thanks to the Jonatan died in 1827.“He was pinned her origins to Benin, or
inequality can provide the same book The Man Who Stole Himself. buried in an unmarked grave, maybe Cameroon or Nigeria.
security assurances for a network Jonatan was born in 1784 on the so his remains may exist, but Either she or her ancestors were
as the simpler version does for Caribbean island of St Croix, then we don’t know where they are,” probably abducted from there.
point-to-point contact. There is just part of the Danish West Indies. His says Agnar Helgason of deCODE. “This is an amazing piece of
one problem: figuring out what this mother, Emilia Regina, was a black Now deCODE has rebuilt much work,” says Robin Allaby at the
equation looks like is very difficult. woman kept as a slave. His father of the DNA Jonataninherited from University of Warwick, UK. But it
The pair overcome this by using is thought to have been a Danish may not be possible to reconstruct
a technique from machine learning secretary, Hans Gram. Jonatan other people’s DNA in the same
called causal inference to study the became a slave on a plantation. way. “This seems to be the sort of
structure of the network. Essentially, The plantation’s Danish owner analysis you could only do under
a computer analyses the direction returned to Denmark in 1789, particular circumstances.”
of information flow between the taking Regina and later Jonatan. Stefánsson is more optimistic.
different nodes to figure out its causal After fighting in the Napoleonic “It’s all a question of the amount
structure. For example, if node A is wars, Jonatan declared himself a of data you have,” he says. “What
connected to node C via node B, free man, as slavery was illegal in made it easy in Iceland was that
A and C can’t communicate unless Denmark. In a court case in 1801, there were no other Africans.”
the message goes via B first (Physical his lawyer argued he could no In theory, we could get the DNA
Review Letters, doi.org/ch89). longer be kept as a slave. But the of historical figures or ancestors.
Knowing this structure lets the pair judge ruled that he should be sent “Any historic figure born after
come up with a Bell inequality for any back to the Danish West Indies, HELGA TOMASDOTTIR 1500 who has known descendants
kind of network, which can be used to where slavery was still legal. So could be reconstructed,” says
guarantee its security. Jacob Aron ■ Jonatan escaped to Djúpivogur, Helgason. Andy Coghlan ■

20 January 2018 | NewScientist | 9