16 | New Scientist | 20 February 2021
THE origins of Stonehenge
have long been a mystery.
Now new discoveries indicate
that the iconic monument may
have started as a stone circle in
Wales that was then dismantled
and rebuilt 280 kilometres
away at its current location
on Salisbury plain.
This is the conclusion of
a team of archaeologists
who uncovered the remains
of what appears to be Britain’s
third-largest stone circle, in
the Preseli hills of west Wales.
Stonehenge was built in
several phases between about
3000 and 2000 BC, starting
with a large circular ditch and
bank together with a circle of
2-metre-high bluestones just
inside. Later, these bluestones
were moved, and bigger
structures made from boulders
known as sarsens were built.
In 2015, a team led by Mike
Parker Pearson at University
College London revealed that
the bluestones came from
quarries in the Preseli hills,
280 kilometres away in Wales.
The team then looked for
evidence of stone monuments
close to these quarries, because
the people who extracted
Stonehenge’s bluestones might
have built stone circles here too.
The archaeologists excavated
at a site called Waun Mawn,
which had four large stones
seemingly placed in an arc. They
uncovered evidence of six holes
that each originally held a stone,
suggesting that there had once
been a full stone circle at the site.
“The arc did continue –
that was a really important
moment,” says Parker Pearson.
Extrapolating from these
positions, the team estimates
that the completed circle
probably had 30 to 50 stones,
though arranged morehaphazardly than the original
bluestone circle at Stonehenge.
A number of strands of
evidence suggest that stones
from Waun Mawn formed part
of the original stone circle at
Stonehenge. Dating studies
showed that the Waun Mawn
stone circle was created between
3600 and 3200 BC, a few
hundred years before the first
stages of construction at
Stonehenge, and the types of
stone at the two sites match.
One of the stone holes at
the Welsh site has an unusual
pentagonal shape, similar
in shape and size to that of
bluestone 62 at Stonehenge.
“It could have been in that hole.
It’s not categorical proof, but it
is really very suggestive,” says
Parker Pearson. The sizes of
the two circles also match
(Antiquity, doi.org/fvdw).
“It’s a really interesting study
that shows some nice arguments
for a link between both stone
circles,” says David Nash at the
University of Brighton, UK,
who last year published a
study identifying the origins
of Stonehenge’s sarsens.
Others are less convinced.
“They’ve got a ragbag of stonesand I’m rather sceptical of
it being a stone circle,” says
Tim Darvill at Bournemouth
University, UK, who has
carried out many studies
of^ Stonehenge.
Further excavations are
planned at Waun Mawn to
clarify the picture. But if
Stonehenge was rebuilt from
a Welsh stone circle, this could
help explain why Neolithic
people went to such lengths
to construct the monument.
Studies of the isotopes in
cremated remains of the earliest
people interred at Stonehenge
indicate that some of them
probably came from west
Wales. This has led Parker
Pearson to conclude that
Stonehenge was built to
commemorate the ancestors
of the original people who
lived near Stonehenge. ❚THE pattern of veins on the back
of someone’s hand is as unique
as a fingerprint and can be used
to identify them, even in images
from a cheap commercial camera.
The technique could be used in
smart door locks or to pick out
people using CCTV images.
Syed Shah at the University
of New South Wales in Australia
and his colleagues used images of
35 volunteers, taking 500 photos
of the back of one of their hands
with a commercial Intel RealSense
D415 camera. It is sensitive to
infrared light, so it can differentiate
blood in veins from body tissue, and
can detect how far away an object is
with stereo lenses, helping to isolate
the hand from the background.
The pattern of veins in each
image was extracted and further
processed for clarity, then used to
train a neural network to connect a
pattern to a particular person. Shah
used the resulting model to identify
the volunteers with an accuracy
of 99.8 per cent (IET Biometrics,
doi. org/fvck). The researchers also
tested the AI’s ability to detect vein
patterns that weren’t included in the
original data set. Four new subjects
were identified as unknown with
96 per cent accuracy.
The technique is more robust
to hacking than existing biometric
tests, says Shah. Fingerprints can
be collected from smooth surfaces
and used to trick sensors, while
face recognition can sometimes be
fooled with a photo. The team also
found that vein detection works
reliably on people of all ethnicities,
which has been an issue for some
biometric tests.
Shah believes the technology can
be adapted to run on smartphones.
Apple’s iPhone 12 already has a
built-in lidar scanner that can detect
range, and many cameras are able to
detect at least some infrared light.
He also believes it could eventually
work with CCTV cameras. ❚Archaeology Artifical intelligenceAlison George Matthew SparkesNews
Stonehenge may be a
recycled Welsh structure
AI can identify you
by the vein patterns
on your handsA.^ STA
NF
ORDThe dismantled
stone circle
at Waun Mawn
(above) and
bluestone 62 at
Stonehenge (right)