Posted on 02/14/2004 10:27:34 AM PST by blam
Left-handedness common in Ice Age
By Dr David Whitehouse
BBC News Online science editor
A right-hand print signifys left-handedness
The fraction of left-handed people today is about the same as it was during the Ice Age, according to data from prehistoric handprints. They were found in caves painted during the Upper Palaeolithic period, between 30,000 and 10,000 years ago.
Left-handedness may have conferred prehistoric man advantages, such as in combat, say the researchers.
The research is published in the February issue of the journal Biology Letters.
Evolutionary advantages
When Stone Age man produced their remarkable cave paintings they often left handprints on the walls produced by blowing pigments from one hand through a tube held by the other hand.
Charlotte Faurie and Michel Raymond at the University of Montpellier, France, deduced the prehistoric cave painters' handedness by spraying paint against cave walls to see which hand they pressed against the wall, and therefore did not use for drawing.
Looking at 507 handprints from 26 caves in France and Spain, they deduced that 23% of them were right-handed, which indicated that they were made by left-handers.
In the general population today about 12% are left-handed, though populations vary considerably, between 3 and 30%.
Because handedness has a genetic component the researchers wondered why the proportion of left-handers should have remained so constant over 30,000 years - the age of the oldest cave studied.
They suggest that because left-handedness is relatively rare it provides certain advantages over those who are right-handed, such as in solo and group fighting.
The researchers say their findings add to the evidence that the evolutionary forces that cause right- and left-handedness are independent of culture.
One morning the two sides of my brain stopped talking to one another.
I'm not making this up!
I was just waking up and I was looking down toward the foot of the bed. I was on my back and both of my arms were at my sides and on top of the covers. At that angle, my right arm was only visible to my right eye and my left arm was only visible to my left eye. I wanted to scratch my nose so I began to raise my left hand to do that. As I slowly raised my arm, the scene in my left eye was unchanged. I could feel my arm moving, but I couldn't see anything happening; my arm looked like it was still lying at my side. Suddenly my left hand came floating into my right eye's field of view. And all the while, my left eye was still showing me an unmoving left arm at my side! Of course, I was startled at the floating, disembodied hand coming toward my face and the scene in my left eye changed to show my now raised left arm. I then realized that I was literally half asleep. The left side of my brain was fully awake and seeing the room as it really was. The right side of my brain had drifted back to sleep and was showing a dream version of the room, complete with a resting left arm. The two hemispheres had briefly stopped talking to one another.
They're friends again now, by the way.
The entire body has a "handedness." One kidney filters more than the other, one ovary ovulates more than the other, one breast is larger and more productive than the other. With bilateral animals, this is usually the case.
I believe there may be a cognitive difference between (some) left-handed people and the majority, and that this can lead to social problems in youth. Part of the problem is that the ability to write is something that right-handed people do better, simply because writing models are geared to what is possible with the right arm. In early school years, ability to write is critical in learning to read, and in learning in general.
Later in life, all of those efforts to get along, taken together, can lead to social skills that are advantageous.
Bad pun. ;-p
..such as driving...LH turns?
My other thought was that if you were walking along a cave, you would use your right hand to brace yourself...just like in the movies.
But the real questions are...Who the hell cares? and who's picking up the tab for your "prestigous" conclusion? Wait, let me guess!
And who's to say how many prints did you miss to come up with the conclusion?
Exactly what I was thinking. Combine this with the other freeper's idea that the owner of the hand may not be the artist and it makes a lot of sense.
"Hey, Ugluck! Help me put my handprint on this wall. Man, THIS is the hand that killed the great cave bear! I want everyone to see it! I'll hold it up while you blow paint over it. Then we'll break open a couple of cold ones. HA! Me make Ice Age joke!"
I started-out the same way.
It made sense to me--when one hand got tired, I would switch to the other.
Eventually, I grew to favor my left hand for writing, because I could see where I was going (though it does smear the ink if one's not careful).
While we're picking this article apart, who says being left-handed is an advantage in combat? If it is, why didn't natural selection occur, increasing the percentage of lefties?
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.