New Scientist - USA (2020-07-18)

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

IER

BL

AN

CO

News In brief

Climate change may

widen range of Zika

Climate change may help

spread the mosquito-borne

Zika virus to cooler regions.

In the most drastic model of

global warming, the risk of

transmission will increase

in southern and eastern

Europe, the northern US,

northern China and

southern Japan by 2080

(Proceedings of the Royal

Society B, doi.org/d3fk).

Windows that cut

noise but let in air

Small speakers fixed to

the outside of a window

can halve the noisiness

of urban traffic, reducing

the sound coming through

an open window by up to

10 decibels. A sensor allows

the speakers to emit sound

at the same frequency

as the noise outside,

cancelling it out (Scientific

Reports, doi.org/d3fm).

Quick swimming

traits evolved twice

A 24-million-year-old

fossil of a giant tusked

dolphin lacks vertebrae

and pectoral bones that

help modern dolphins and

baleen whales swim faster.

This suggests that whales

and dolphins separately

evolved these adaptations

for more efficient

swimming (Current

Biology, doi.org/d3fn).

LE

SL

EY

WO

OD

PH

OT

OG

RA

PH

Y

Really brief