Ancient Lefties: The History of Obama's Handedness
Earl Evleth
No big deal, I type with both hands.
Ancient Lefties: The History of Obama's Handedness
Something sinister is going on, and newly-inaugurated President Obama is
behind it.
From the Latin for left, "sinistra," southpaw Obama is another notch for
the column of left-handed presidents, now totaling eight - a proportion (out
of all 43 men who have been POTUS) that is well above their representation
in the total population, which hovers around 10 percent.
(Let's count James A. Garfield as a lefty, although some say he was
ambidextrous and others say he was a lefty; many ambis are lefties who learn
to do some tasks with their right hands.)
In fact, every president since 1974 with the exception of Jimmy Carter and
George W. Bush has been left-handed, as is Obama's former Republican
opponent Sen. John McCain. Al Gore is too.
Is it just a coincidence, or is there something about being left-handed
that can make for a more presidential demeanor?
Some evolutionary advantage, whether overall greater intelligence or
language skills, has kept a stable group of lefties for at least the past
200,000 years, said Chris McManus, professor of psychology and medical
education at University College London.
Left-handed tools chipped 500,000 years ago
There have been lefties for as long as there have humans, historians agree.
Some of the oldest evidence of left-handedness comes from Kenya, where of a
500,000 year-old cache of 54 stone tools made by one of our pre-human
ancestors, six (or about 11 percent) were chipped using the left hand.
Similarly, Neanderthals working with meat and stone tools more than 150,000
years ago left marks on their teeth at left and right angles - indicating
opposite hand use - in almost perfect proportion with today's 9:1 ratio.
Paleolithic cave paintings from France and Spain also hint that lefties
walked among our ancestors about 30,000 years ago. Studying a collection of
so-called negative hand drawings on the cave walls - similar to tracing one
hand with the other - scientists found that individuals drew their left hand
much more frequently than the right.
The laundry list of lefties goes on through history, with records telling
us that a number of famous ancient figures probably favored their southpaw
as well, from Alexander the Great to Charlemagne, Holy Roman emperor.
Though ancient sample sizes are small and poor estimates of the exact
proportion of lefties, the existence of left-handedness is clear even
hundreds of thousands of years ago, McManus said.
Left tied to language
Despite its long history, left-handedness is a uniquely human trait.
Chimpanzees and gorillas, with whom we share an ancestor and a number of
common physical attributes, don't seem to favor one hand over the other.
Instead, left-handedness may have developed along with another
characteristic known just to humans - language.
Most people process language in the left side of their brain, the
hemisphere that also controls the right side of the body, and have done so
presumably since humans started chatting a few hundred thousand years ago.
Whichever gene made the left side of our brains responsible for language
also played a role in making our right side dominant, experts such as
McManus believe.
Though a specific left-handed gene has yet to be found, the trait to choose
one hand over the other is likely inherited, agree scientists. Left-handed
parents are far more likely to produce left-handed children, and those
children appear to begin favoring that hand in the womb, according to a 2004
study on 10-week-old fetuses.
More recent research suggests that, while developing, the two sides of the
brain actually "fight" for specialized control of certain functions, such as
handedness, with the left side (which controls the right - are you
following?) more often coming out on top.
Interestingly, even when the right side wins, the left brain often shares
some of the duties, studies have shown. So while right-handed people usually
process language exclusively in the left side of their brain, lefties
process language mostly in the right but partly on the left as well.
That preferential wiring may make lefties more adept at certain skills
required for leadership according to McManus, who wrote about his theories
in his book "Right Hand, Left Hand" (Harvard University Press; 2002).
Runge13
"Earl Evleth" <evl...@wanadoo.fr> a écrit dans le message de
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