2021-01-30_New_Scientist

36 | New Scientist | 30 January 2021

Neanderthal DNA – or modern human

DNA. It was something never seen before.

After initially referring to the individual

as “X-woman”, Shunkov and Pääbo settled

on “Denisovans” as a name for the group.

The findings were published in 2010.

Never before had a group of hominins been

identified solely from its DNA. Another

surprise was to come, however. Some of the

Denisovan DNA sequences matched those

found in people living on the islands of

Melanesia, especially Papua New Guinea.

The implication was that thousands of years

ago, Denisovans and members of our species,

Homo sapiens, had sex and produced children.

As a result, today around 5 per cent of the

DNA of Melanesian people is Denisovan,

with many of these genes appearing to

play key roles in immunity to diseases.

In itself, the interbreeding wasn’t too

big a shock. Pääbo’s team had published

the sequence of the Neanderthal genome

earlier in 2010, revealing that H. sapiens

and Neanderthals interbred, and that all

humans today whose ancestral group

developed outside Africa carry some

Neanderthal DNA. But the Denisovan

interbreeding was odd because their DNA

was found thousands of kilometres away

from Papua New Guinea in Denisova cave.

The implication was that Denisovans

were once widespread (see “How far did

Denisovans roam?”, right). In fact, their

“demographic and evolutionary core” was

probably in south Asia, says Jean-Jacques

Hublin, also at the Max Planck Institute

for Evolutionary Anthropology.

This was all based on DNA from a single

finger bone. There was no skeleton, and no

artefacts. The Denisovan people themselves

were a total mystery. A study published

in 2019 sought to address this by using the

Denisovan genome to deduce what they

looked like. Researchers identified methyl

“tags” attached to the genome, which

reveal how active each gene was, and used

that information to generate an image of

a Denisovan face. However, the study was

widely disputed, not least because nobody

Excavations at

Denisova cave

(above and below)

have yielded

few Denisovan

remains, but

thousands

of artefacts

including bone

points and tooth

pendants (left)

T-B

SH

UT

TE

RS

TO

CK

/IG

OR

BO

SH

IN;

KA

TER

INA

DO

UK

A;^ S

PU

TN

IK/

SC

IEN

CE

PH

OT

O^ L

IBR

AR

Y

“ Denisova cave

in Siberia was

probably the

Denisovans’

northern limit”

1 cm