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November 2012, Week 2

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Fri, 9 Nov 2012 23:14:51 -0500
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Oldest Arrowheads Hint at How Modern Humans Overtook
Neandertals

By Kate Wong
November 7, 2012
http://blogs.scientificamerican.com/observations/2012/11/07/oldest-arrowheads-hint-at-how-modern-humans-overtook-neandertals/

Archaeologists excavating a cave on the southern coast
of South Africa have recovered remains of the oldest
known complex* projectile weapons. The tiny stone
blades, which were probably affixed to wooden shafts
for use as arrows, date to 71,000 years ago and
represent a sophisticated technological tradition that
endured for thousands of years. The discovery bears on
an abiding question about when and how modern human
cognition emerged, and suggests a way by which early
modern Homo sapiens outcompeted Neandertals to
eventually become the last human species standing.

Fossils show that humans who basically looked like us
had evolved by around 200,000 years ago. Yet based on
the cultural stuff they left behind, it looked as
though anatomically modern humans didn’t begin thinking
like us until much later. And when the creative spark
did eventually ignite, the flame flickered only briefly
before fizzling, only to spark and fade again and again
as populations died out, taking their innovations to
the grave. Complex projectile weapon technology, for
example, seemed to make a brief first appearance
sometime between 65,000 and 60,000 years ago and didn’t
stick until after 40,000 years ago. But whether this
flickering pattern in the archaeological record is real
or merely an artifact of the small number of sites
excavated has been unclear. The new South African
finds, which come from a site called Pinnacle Point 5 –
6 (PP5-6), support the latter scenario.

Archaeologists have often focused on symbolic
remains—from body ornaments, such as beads, to
engravings and paintings on cave walls—in their search
for clues to the origin of the modern mind. The idea
being that this symbolic stuff is a good indicator that
whoever made it had language, a hallmark of modern
human cognition. In a paper detailing their discovery
published in the November 8 Nature, Kyle S. Brown of
the University of Cape Town, Curtis W. Marean of
Arizona State University and their colleagues make the
case that the advanced technology represented by the
tiny stone blades they found at PP5-6 is also a proxy
for complex cognition. (Scientific American is part of
Nature Publishing Group.)

To craft the stone points, the people at PP5-6 first
had to locate and collect a specific type of stone
called silcrete. They then had to gather wood and
transport it to a designated spot to build a fire to
treat the stone, heating it to just the right
temperature to make it easier to shape. After carefully
chipping away at the rock to form tiny, sharp blades,
they made mounts for the blades from wood or bone, and
joined the stone to the mounts with mastic to create
composite tools in the form of arrows or darts. The
persistence of such a complex projectile technology for
11,000 years at PP5-6 (and the persistence of heat
treatment of stone for 100,000 years at Pinnacle Point,
which previous research documented) implies that people
across a large region were using it and transmitting
the recipe from one generation to the next verbally,
according to the researchers.

“These operations would no doubt have taken place over
the course of days, weeks or months, and would have
been interrupted by attention to unrelated, more urgent
tasks,” observes paleoanthropologist Sally McBrearty of
the University of Connecticut in a commentary
accompanying the team’s report. “The ability to hold
and manipulate operations and images of objects in
memory, and to execute goal-directed procedures over
space and time, is termed executive function and is an
essential component of the modern mind,” she explains.

McBrearty, who has long argued that modern cognitive
capacity evolved at the same time as modern anatomy,
with various elements of modern behavior emerging
gradually over the subsequent millennia, says the new
study supports her hypothesis. A competing hypothesis,
advanced by Richard Klein of Stanford University, holds
that modern human behavior only arose 50,000 to 40,000
years ago, as a result of some kind of fortuitous
genetic mutation that kicked our ancestors’ creativity
into high gear. But discoveries of symbolic items much
older than that supposed mutation–and older than the
PP5-6 arrowheads for that matter–have cast doubt on
Klein’s theory. And other finds hint that Neandertals,
too, engaged in symbolic behaviors, which would suggest
that the capacity for symbolic thinking arose in our
common ancestor perhaps half a million years ago.

Brown and his collaborators conclude by noting that
this projectile technology, which allows one to attack
from a safe distance, would have given modern humans a
significant edge during hunting and interpersonal
conflict as they spread out of Africa into Europe and
encountered the resident Neandertals equipped with
handheld spears. McBrearty agrees, writing, “if they
were armed with the bow and arrow, they would have been
more than a match for anything or anyone they met.”

*Updated 10/08/12 at 2:00 p.m. to specify that the
newly discovered artifacts are remains of complex
projectiles as opposed to simple ones, such as hand-
cast spears.

About the Author: Kate Wong is an editor and writer at
Scientific American covering paleontology, archaeology
and life sciences. Follow on Twitter @katewong.

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