New Scientist Australian Edition – 24 August 2019

24 August 2019 | New Scientist | 17

Ancient humans

Solar system Health

Humans helped to

wipe out cave bears

Cave bears roamed Europe

for 100,000 years in large

numbers. Now an analysis

of the DNA of the extinct

animals shows they began

to decline 40,000 years

ago – as modern humans

arrived in their habitat

(Scientific Reports, doi.org/

c9g3). Our ancestors may

have occupied the caves

the bears relied on.

Sleep loss worse

than social media

Girls aged 13 and 14 who

use social media frequently

tend to be less happy and

more anxious than those

who use it less. But taking

into account sleep, physical

activity and cyberbullying,

the effect of frequent social

media use was found to be

insignificant (The Lancet

Child & Adolescent Health,

doi.org/c9gz).

Mystery methane

pinned on fracking

Levels of the greenhouse

gas methane have been

rising since 2008, but the

cause has been unclear.

A study suggests fracking

for shale gas is largely to

blame (Biogeosciences,

doi.org/c9hs). If fracking

continues to grow, it will

endanger the goals of the

UN’s Paris climate deal, the

researchers warn.

Neanderthals took

to life by the water

GROWTHS in Neanderthals’ ears

indicate that aquatic foraging was

a big part of their life. The finding

suggests that they were adaptable

and could live in a range of

environments.

Erik Trinkaus at Washington

University in St Louis, Missouri,

and his colleagues investigated the

ear remains of 77 ancient humans

that lived in western Eurasia in the

mid-to-late Pleistocene period.

They looked for dense, bony

A GIANT impact 4.5 billion years

ago could explain why Jupiter’s

core is stranger than expected.

Astronomers thought that Jupiter

began as a rocky and icy planetary

embryo that later formed its

massive gaseous envelope by

drawing in hydrogen and helium

from material swirling around the

sun. This would mean there was a

relatively clear delineation between

the solid core and the gas around it.

However, that doesn’t appear to

be the case. Over the past few years,

measurements by NASA’s Juno

probe of Jupiter’s gravitational field

suggest the solid core is mixed with

hydrogen through a lot of its radius.

To investigate, Shang-Fei Liu of

Sun Yat-sen University in Zhuhai,

China, and his team modelled a

scenario where, 4.5 billion years

ago, a big planetary embryo

smacked into Jupiter. “Jupiter’s

primordial compact core was

destroyed, and a dilute core-like

structure formed,” says Liu. The

simulations show the effects would

remain within Jupiter until this day,

fitting what has been observed by

Juno (Nature, doi.org/c9g2).

These sorts of collisions weren’t

rare at the time, says Vincent Eke

at Durham University, UK. However,

Liu’s hypothesis will be hard to

test directly. Abigail Beall

growths in the ear canals found

in people who spend a lot of time

in cold, wet and windy places, a

condition known as “surfer’s ear”.

The researchers were surprised

to find that around half of the

23 Neanderthals they studied

had signs of these growths. They

were at least twice as prevalent as

in any of the other ancient human

groups the team looked at. This

suggests Neanderthals foraged

in water, something that wasn’t

obvious from other archaeological

clues (PLoS One, doi.org/c9hq).

“It all reinforces what is

becoming increasingly clear from

Immune cells help

gallstones to grow

WE KNOW that gallstones grow

from crystals in the gallbladder,

but it has been unclear how these

stick together. Now it seems

immune cells are to blame – a

finding that could lead to new

treatments for the condition.

Martin Herrmann at the

Friedrich-Alexander University

Erlangen-Nürnberg in Germany

and his colleagues made this

discovery while studying small

stones in the bile of people

undergoing operations to treat

their gallstones.

On the small stones were telltale

signs of neutrophil extracellular

traps – sticky webs of DNA released

by immune cells to catch invading

microbes. The presence of large

clumps of DNA and an enzyme

used by neutrophil immune

cells suggested that these cells

had been targeting bile crystals.

To test this, researchers mixed

cholesterol crystals, which are a

component of many gallstones,

with human neutrophils. The

neutrophils shot DNA at the

crystals. When exposed to

neutrophils, gallstone surfaces

quickly collected neutrophil DNA.

These sticky webs pulled

cholesterol and calcium crystals

together to form larger stones

(Immunity, doi.org/c9hk). RPS

diverse forms of evidence: that the

Neanderthals were capable and

flexible, and not the benighted

deficients that some persist in

calling them,” says Trinkaus.

It is possible Neanderthals had

a greater risk of developing the

growths due to genetics, but the

different landscapes they lived in

and proximity to water may also

explain why they had more than

other groups, says Trinkaus.

We know from modern surfers

that the growths normally cause

little or no discomfort, but they

can result in partial deafness.

Ruby Prosser Scully

Jupiter’s weird innards may

be due to ancient collision

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Really brief

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