HUMANS & SOCIE TY
How megaliths spread across Europe
Giant stone monuments are traced back to northwest France
BODY & BRAIN
Scans find key sign
A complex brain activity
pattern comes with awareness
BY BRUCE BOWER
From simple rock arches to Stonehenge,
tens of thousands of imposing stone
structures dot Europe’s landscapes. The
origin of these megaliths has long been
controversial. A new study suggests that
the constructions first appeared in France
and spread across Europe in three waves.
The earliest megaliths were built in
what’s now northwestern France as early
as about 6,800 years ago, says archaeologist Bettina Schulz Paulsson of the
University of Gothenburg in Sweden.
Knowledge of these stone constructions
then spread by sea to societies along
Europe’s Atlantic and Mediterranean
coasts, she contends in a study published
online February 11 in the Proceedings of
the National Academy of Sciences.
“European megaliths were products
of mobile, long-distance sea travelers,”
Schulz Paulsson says.
About 35,000 megalithic graves, stone
BY LAURA SANDERS
A conscious brain hums with elaborate,
interwoven signals, a study finds.
Scientists uncovered that new signature of consciousness by analyzing
brain activity of healthy people and
of people who were not aware of their
surroundings. The result, published
online February 6 in Science Advances,
makes headway on a tough problem:
how to accurately measure awareness
in patients who can’t communicate.
Other methods for measuring con-
sciousness have been proposed. But
because of its size and design, the new
study was able to find a particularly
circles, standing stones and stone build-
ings or temples still exist, many near
coastlines. Radiocarbon dating has sug-
gested that these structures were built
between about 6,500 and 4,500 years ago.
Scholars a century ago thought that
megaliths originated in the Near East or
the Mediterranean area and spread else-
where via sea trading or land migrations
by believers in a megalithic religion.
But as absolute dates for archaeological
sites began to emerge in the 1970s, sev-
eral researchers argued that megaliths
emerged independently among a hand-
ful of European farming communities.
Schulz Paulsson used statistical tests to
identify a model that explained the origin
and spread of megaliths at 154 sites. Her
calculations relied on 2,410 radiocarbon
dates. Some sites included presumed
megalith precursors, such as small graves
dug into the ground or large earthen
monuments, that aided in reconstructing
strong signal. The research “produced
clear, reliable results that are directly
relevant to the clinical neuroscience of
consciousness,” says cognitive neuroscientist Michael Pitts of Reed College
in Portland, Ore.
Consciousness is a squishy concept.
It slips away when we sleep and can be
distorted by drugs or lost in accidents.
Though scientists have proposed many
biological explanations for how our
brains create consciousness, a full definition is still elusive.
By finding a clear brain signature of
awareness, the new work “brings us
closer to understanding what consciousness is,” says study coauthor Jacobo Sitt
of INSERM in Paris.
Sitt and colleagues scrutinized functional MRI data that captured the brain
activity of 125 people as they rested inside
scanners at research institutes in Paris,
New York City and Liège, Belgium. Forty-seven participants were healthy. The rest
Rock structures may have spread across
Europe in three waves. This stone grave on
Sardinia in Italy dates to about 5,000 years ago.
where and when megaliths spread.
The earliest megalithic graves consisted of two or more standing stones
topped by a third stone or by a mound
of earth. That construction style spread
from northwest France down the Atlantic
coast and into the Mediterranean
between about 6,800 and 6,000 years
ago, Schulz Paulsson says. Large earthen
graves without stones were built shortly
before the rise of megaliths and appear
only at sites in northwest France, pegging that region as the likely birthplace
of megalithic graves, she contends.
A second type of megalith gained
widespread popularity about 6,000
to 5,500 years ago, Schulz Paulsson
had unresponsive wakefulness syndrome,
in which their eyes were open but they
showed no signs of awareness, or were
in a minimally conscious state, in which
they could follow simple instructions
such as moving their eyes on command.
Two distinct patterns of brain activity
emerged. The first was a complex pattern
characterized in part by opposites. When
one neural spot was active, others were
not. This pattern didn’t follow the brain’s
anatomy; signals ping-ponged far away
from their known anatomical connections. The second pattern, however, was
simpler and more closely constrained
by the brain’s anatomy. (The scientists
found two other patterns, but those didn’t
correspond to consciousness.)
The brains of people who were fully
conscious spent more time exhibiting
the complex pattern. People with unresponsive wakefulness syndrome spent
more time in the simple pattern, while
those in the minimally conscious state