Left-Handedness Common In Ice Age

BBC ^ | 2-14-2004 | Dr David Whitehouse

[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.

[Uncle Meat]

Left-Handedness Common In Ice Age

I can see why.Those cave women were godawful ugly back then.

[Kay Ludlow]

I wouldn't know... I'm ambidextrous.

Really? So am I. It results in some interesting experiences in life. I also don't think like other people. In problem solving I often come to the same conclusions as others, but get there from an entirely different approach. On the other hand, sometimes I just come to conclusions that are bizarre - as even I realize after the fact.

[Ophiucus]

However, I am aware of no research that has been done to support or deny this hypothesis.

It's ongoing - out of curiosity, I started going through some search results, surprising number on pubmed, and fun stuff on google.

Here's someone at IU who seems to be into it.

Here's a fun one indicating that cultural pressure back to the medieval time hasn't affected the distribution.

The left side speech and right handedness has been postulated but I don't think it has much to support it. It's one of those fun conundrums.

[HighWheeler]

"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."

Their deduction relies on a single assumption that cave painters put their palm side down when they sprayed.

Thousands of years ago, some of the cave painters used to hold their palm side up when they did the shadow method, so they could turn their hand over and press a positive print on another area.

I made up that scenario, but you can see how analysis without considering multiple legitimate possibilities can drive a wrong deduction.

[Ophiucus]

Here's a list of theories merits and arguments against. Causation of handedness

[Lucky Dog]

Thanks for the links... Interesting new material supporting other material I have reviewed elsewhere.

[PoorMuttly]

Nonsense. I happen to know that they made an image of the hand they used to paint with.

Case closed.

[CholeraJoe]

2) a minority of more ambidextrous people of whom some become right- and other left-handed.

That would be me. Shoot, throw and kick with the right appendage, right eye dominant. Write, brush teeth, use fine instruments like scalpels with the left. Sew (or suture), write on a chalkboard, eat, with either. Use toilet paper with the politically incorrect hand for the Muslim world.

[Ophiucus]

Thanks for the links... Interesting new material supporting other material I have reviewed elsewhere,/i>

No prob - it's an interesting question.

[Askel5]

=== The societal decision could have just as easily been to use the right hand for "hygiene" purposes rather than the left.

I don't think so. If the right hand is the more facile and used for more things, just makes sense to leave it the Clean Hand, as it were.

It's like keeping one hand wet and one hand dry when dredging seafood for frying. You keep the dominant hand "clean".

[Askel5]

== According to him, more lefties are geniuses.

Hear hear. =)

[<1/1,000,000th%]

It's that eat with your right hand, wipe with your left hand thing.

;)

[marsh2]

I am the only right hander in my family. My children will set the table backwards to get even with me.

[Trajan88]

I bat right handed and throw left... I'm a freak.

I propose the new, improved baseball diamond: 3rd base is now 1st and what was 1st is now 3rd.

Who's with me?

Just kidding... of course there will be some bleeding heart lib lawyer that will take up the cause.

Trajan88

p.s. Bush in 2004!

[Trajan88]

For my first little league team practice my dad sent me off with his old glove for the left hand. I couldn't throw righty (with all due respect... I threw like a girl). One of my teammate's dad gave me a glove for the right hand and wa-la... the "affliction" was cured.

When my folks picked me up after practice they asked how it went. I told them that I couldn't use dad's glove because I was more comfortable throwing left.

I distinctly remember my folks asking if I was sure about that. I said yes.

Note: this was back in 1972.

Trajan88; #23 - outfielder, Plano (TX) Yankees

[anymouse]

Actually your heart is more or less in the center of your chest cavity (ask a Dr.), so that is a false argument about protecting the heart from attack.

Now in fighting being a lefty has benefits and drawbacks when fighting a righty. If a lefty feigns being a righty, he can sucker punch the righty, but he also has to defend with an awkward parry stroke.

[Psycho_Bunny]

Wow...talk about reaching for conclusions.

This article is a complete and total crock.

[CapandBall]

Yes, the heart is more or less in the center of your chest cavity, but slightly to the left. Every little bit helps.

I never thought of feigning being a righty when up against another righty. It might work for the first blow, but I still dont see a big advantage.

[anymouse]

Well apparently our ancestors (and some current cultures) did see the advantage, that is why they invented the right handed wave, salute and handshake as peaceful gestures to show that one was not armed. They shunned shunned lefties, fearing that they might attack with the left hand while waving, saluting, or handshaking with the right hand.

Interesting note that in the 1992 and 1996* elections all three principle Presidential candidates where left handed. (* Of course Sen. Dole was a forced lefty due to his war injury.)

[CapandBall]

Fascinating... and logical.

I'm wondering when in human evolution/history we started favoring right or left? When tools were devised?

What about animals? do they favor a side, or are they apedexterous (sp?)

Alternatly (for the religious type) were we "created" predominatly right-handed?