18 | New Scientist | 18 July 2020
Biotech
Americans
and Pacific
islanders met
800 years ago
POLYNESIANS and Native
Americans met and had children
together about AD 1200, modern
genomes show. But the encounter
didn’t take place on Easter Island
(Rapa Nui), the Polynesian island
closest to South America.
Beginning about 5000 years
ago, people sailed from South-East
Asia into the Pacific and discovered
hundreds of islands. Easter Island,
the easternmost of the group,
was the last to be settled.
This story is backed by genetic,
archaeological and linguistic
evidence, but there were clues
that Polynesians might also have
some Native American ancestry.
“There is the sweet potato
in Polynesia, even though it
Climate change Anthropology^
Mitochondria edited
for the first time
THE cell structures that turn food
into energy have been genetically
edited for the first time.
Mitochondria have their own
genomes, and mutations in this
DNA can lead to muscle disorders
or even prove fatal in childhood.
Standard gene-editing
techniques don’t work with
mitochondria, however, hindering
efforts to develop treatments. For
instance, most gene editors cut
DNA, but mitochondrial genomes
break down if sliced.
Now David Liu at the Broad
Institute in Massachusetts and
his team have collaborated with
two other groups to create a
new kind of editor. In tests in
human cells growing in a dish,
this made the desired change in
up to 50 per cent of mitochondrial
genomes (Nature, doi.org/d3gd).
Michael Le Page
Sprinkle rock dust to
limit global warming
SPREADING rock dust on cropland
globally could absorb about a
tenth of our “carbon budget”, the
amount of carbon dioxide humans
can emit without triggering
catastrophic climate change.
Rocks naturally absorb CO 2.
This can be accelerated by grinding
them up to increase their surface
area, a process called enhanced
rock weathering.
David Beerling at the University
of Sheffield in the UK and his team
modelled its potential. They found
that rock dust could remove
between 0.5 and 2 gigatonnes of
CO 2 a year by 2050. Humanity’s
fossil fuel use emits about
35 gigatonnes of CO 2 a year.
If 2 gigatonnes of CO 2 were
removed annually over half
a century, it would be equivalent
to 12 per cent of the world’s carbon
budget (Nature, doi.org/d3gh).
Adam Vaughan
was domesticated in, and is native
to, the Americas,” says Alexander
Ioannidis at Stanford University in
California. Some have argued that
the Easter Island statues (pictured)
resemble ancient Peruvian ones.
Geneticists have found evidence
of Native American genes in
Polynesian people, but the results
are disputed. Now, Ioannidis and his
colleagues have sequenced the full
genomes of 354 Polynesian people
from 17 islands, and 453 Native
Americans belonging to 15 groups
from the Pacific coast. Small
amounts of Native American DNA
were found in Polynesians from
the eastern islands, including Easter
Island (Nature, doi.org/d3f6).
The islanders who were the point
of contact were almost certainly
from one of the more westerly
of these islands, the team says.
The genes were later carried east.
But did Polynesians sail east
to South America and back or did
Native Americans stray west?
Either scenario fits the data, says
Ioannidis. Michael Marshall
JAV
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AN
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News In brief
Climate change may
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Climate change may help
spread the mosquito-borne
Zika virus to cooler regions.
In the most drastic model of
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northern China and
southern Japan by 2080
(Proceedings of the Royal
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Windows that cut
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Small speakers fixed to
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OG
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Really brief