The evolution of right- and left-handedness
New study compares handedness of medieval English villagers to modern-day sample
A study from the April issue of Current Anthropology explores the evolution of handedness, one of few firm behavioral boundaries separating humans from other animals. As researchers find new cultural behaviors among chimpanzees and other primates, language is the only other characteristic accepted to be unique to humans, and both language and handedness appear to relate to the separation of functions between the two halves of the human brain, also known as lateralization.
"The predominant right-handedness of humans has been noted since at least the time of the Greek philosophers Plato and Aristotle," write Amanda Blackburn (University of Manitoba) and Christopher Knüsel (University of Bradford). "Modern research has shown that hand preference occurs across human cultures and, through observations of ancient art, in ancient peoples."
The researchers compared two test groups - a modern sample of Canadians and a sample of medieval English villagers - to determine the effect repeated movement had on human skeletons separated by over a thousand years. They found that the majority of active individuals display a high degree of asymmetry.
"We studied two groups, one a modern group of Canadians, for whom we could document hand preference and physical activity histories, as well as the breadth of the part of the humerus that makes up the elbow joint," explain the authors. "We then applied the same measurement to a group of medieval English villagers known to us only through their skeletons. This allowed us to demonstrate the usefulness of this trait to determine changes in hand preference in populations separated in time by over a thousand years."
University of Chicago Press Journals. March 2006.
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