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101103171451.htm
Stone Age Humans Needed More Brain Power to Make Big Leap in Tool Design
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A stone `core' (A) is struck with a hammerstone (B) in order to detach sharp
stone `flakes'. In Oldowan toolmaking (C, top) the detached flakes (left in
photo) are used as simple cutting tools and the core (right in photo) is waste.
In Acheulean toolmaking (C, bottom), strategic flake detachments are used to
shape the core into a desired form, such as a handaxe. Both forms of toolmaking
are associated with activation of left ventral premotor cortex (PMv), Acheulean
toolmaking activates additional regions in the right hemisphere, including the
supramarginal gyrus (SMG) of the inferior parietal lobule, right PMv, and the
right hemisphere homolog of anterior Broca's area: Brodmann area 45 (BA 45)
(Imaging data adapted from [6]). (Credit: Image from Aldo Faisal, Dietrich
Stout, Jan Apel, Bruce Bradley. The Manipulative Complexity of Lower
Paleolithic Stone Toolmaking. PLoS ONE, 2010; 5 (11): e13718 DOI:
10.1371/journal.pone.0013718)
ScienceDaily (Nov. 4, 2010) Stone Age humans were only able to develop
relatively advanced tools after their brains evolved a greater capacity for
complex thought, according to a new study that investigates why it took early
humans almost two million years to move from razor-sharp stones to a hand-held
stone axe.
Researchers used computer modelling and tiny sensors embedded in gloves to
assess the complex hand skills that early humans needed in order to make two
types of tools during the Lower Palaeolithic period, which began around 2.5
million years ago. The cross-disciplinary team, involving researchers from
Imperial College London, employed a craftsperson called a flintnapper to
faithfully replicate ancient tool-making techniques.
Reporting in the online journal PLoS ONE, the team say that comparing the
manufacturing techniques used for both Stone Age tools provides evidence of how
the human brain and human behaviour evolved during the Lower Palaeolithic
period.
Neuroscientist Dr Aldo Faisal, the lead author of the study from the
Departments of Bioengineering and Computing at Imperial College London, says:
"The advance from crude stone tools to elegant hand-held axes was a massive
technological leap for our early human ancestors. Hand-held axes were a more
useful tool for defence, hunting and routine work. Interestingly, our study
reinforces the idea that tool making and language evolved together as both
required more complex thought, making the end of the Lower Palaeolithic a
pivotal time in our history. After this period, early humans left Africa and
began to colonise other parts of the world."
Prior to this latest study, researchers have had different theories about why
it took early humans more than 2 million years to develop stone axes. Some have
suggested that early humans may have had underdeveloped motor skills or
abilities, while others have suggested that it took human brains this time to
develop more complex thoughts, in order to dream up better tool designs or
think about better manufacturing techniques.
The researchers behind the study say that their evidence, from studying both
tool-making techniques, confirms that the evolution of the early human brain
was behind the development of the hand-held axe. Furthermore, the team suggest
that the advancement of hand-held axe production may have also coincided with
the development of language, as these functions overlap in the same regions of
the modern and early human brains.
The flintnapper who participated in the study created two types tools including
the razor-sharp flakes and hand-held axes. He wore a data glove with sensors
enmeshed into its fabric to record hand and arm movements during the production
of these tools.
After analysing this data, the researchers discovered that both flake and
hand-held axe manufacturing techniques were equally complex, requiring the same
kind of hand and arm dexterity. This enabled the scientists to rule out motor
skills as the principal factor for holding up stone tool development.
The team deduced from their results that the axe-tool required a high level of
brain processing in overlapping areas of the brain that are responsible for a
range of different functions including vocal cords and complex hand gestures.
This is the first time that neuroscientists, archaeologists, anthropologists
and flintnappers have teamed together, using cutting edge technology including
data glove sensors and advanced modelling, to develop a deeper understanding of
early human evolution.
In the future, the team plan to use their technology to compare tools made by
Neanderthals, an extinct ancestor of humans, to glean insights into their brain
development.
The study also included researchers from the Department of Anthropology, from
Emory University; Department of Archaeology and Osteology, Gotland University
College; and the Department of Archaeology, Exeter University.
Editor's Note: This article is not intended to provide medical advice,
diagnosis or treatment.
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Story Source:
The above story is reprinted (with editorial adaptations by ScienceDaily
staff) from materials provided by Imperial College London, via EurekAlert!, a
service of AAAS.
Journal Reference:
1. Aldo Faisal, Dietrich Stout, Jan Apel, Bruce Bradley. The Manipulative
Complexity of Lower Paleolithic Stone Toolmaking. PLoS ONE, 2010; 5 (11):
e13718 DOI: 10.1371/journal.pone.0013718
Need to cite this story in your essay, paper, or report? Use one of the
following formats:
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Imperial College London (2010, November 4). Stone Age humans needed more brain
power to make big leap in tool design. ScienceDaily. Retrieved November 6,
2010, from http://www.sciencedaily.com /releases/2010/11/101103171451.htm
Note: If no author is given, the source is cited instead.
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