Sinister business: Lefties have evolutionary boon

February 27, 2009
on February 4, 2009. In a study

Enlarge

US President Barack Obama uses his left hand to sign a bill on February 4, 2009. In a study published on Friday, French evolutionary biologists offer an explanation: left-handedness, they say, has survived because it is so rare.

Under Darwinian pressure, genes that don't help the struggle to survive get squeezed out of the genetic code, leaving the ones that are fitter.

Given that the vast majority of humans are right-handed, why is it that left-handedness -- of which President Barack Obama is a proud practitioner -- is still around?

In a study published on Friday, French evolutionary biologists offer an explanation: left-handedness, they say, has survived because it is so rare.

In prehistoric times, a left-hander would gain the advantage of surprise in fighting against a right-hander, they say.

In addition, left-handers tend to be skilful with their right hand or even ambidextrous. Most right-handers greatly prefer their right paw, which is a disavantage in a situation that demands intermanual coordination.

The paper, headed by Violaine Llaurens of the Institution of Evolutionary Sciences in Montpellier, southern France, estimates that left-handers comprise between five and 25 percent of the population, with important geographical variations.

Although the genes for left-handedness are so far elusive, there is compelling evidence that it is heritable, the authors believe.

If both of your parents are left-handed, the chance that you too will be a southpaw is more than twice than if your parents are right-handed.

Developmental factors could also play a role in left-handedness, such as the exposure to hormones in the uterus.

There is some good news for lefties in the study, which reviews published research in lateralism.

Compared with their low numbers in the general population, lefties are relatively numerous among creative men; among children rated as having an IQ higher than 131; and among individuals who are good at music and maths.

"All these advantages may play a significant role in the social status of left-handers," it says. Some research suggests that left-handed men are better paid than right-handers.

Even though lefties are clear survivors, their condition also carries an evolutionary cost, the authors warn.

They point to statistical surveys that suggest right-handers generally live longer than left-handers, by a few months or even several years.

Why this is the case is unclear. It could be partly explained by the greater number of fatal accidents involving left-handed men grappling with industrial tools, machines and instruments designed for right-handers.

Left-handers also tend to have smaller body size, which is linked to less reproductive success, and they tend to be more numerous in the homosexual population than in the general population.

As homosexuals tend to have fewer children or no children at all, this means that the "lefty" genes are less likely to be passed on, which counts as an evolutionary disadvantage.

The study appears in Philosophical Transactions of the Royal Society B, a journal published by Britain's de-facto academy of sciences.

(c) 2009 AFP

3.6 /5 (13 votes)  

Filter


Move the slider to adjust rank threshold, so that you can hide some of the comments.


Display comments: newest first

bmcghie
Feb 27, 2009

Rank: 3.7 / 5 (3)
"Left-handers also tend to have smaller body size, which is linked to less reproductive success..."

last I checked, 6'3" is not 'smaller.' Then again, I might just be an outlier.
CreepyD
Feb 27, 2009

Rank: 3 / 5 (3)
Is handedness proven to be genetic? Nurture seems more likely to me. I do some things left handed because I learnt them that way. Also some things right handed, again because I learnt it that way. I just happen to learn most things with the right hand, so became 'right handed'.
Velanarris
Feb 27, 2009

Rank: 3.7 / 5 (3)
"Left-handers also tend to have smaller body size, which is linked to less reproductive success..."

last I checked, 6'3" is not 'smaller.' Then again, I might just be an outlier.
No, I'm 6'7" and also a lefty. I don't think lefties tend to be smaller in size, at least I've never seen any evidence to that.

Perhaps the fact handed-ness has zero interaction with survival, and the reason why it's so rare is because society shunned it for centuries? Left handers have been called the devil's children, and had their hands beaten until they used their right hands.

Also the ambidexterity piece is irrelevant because the world didn't become left or right handed until some leader shunned lefties forcing them to become right hand capable.


As for the prehistoric times comment, research is starting to show prehistoric man wasn't too warlike as resources were bountiful compared to the number of people needing them. This made cooperation rather than confrontation the norm as it allowed for a larger hunting group, more successful endeavors, more manual labor for farming, and eventually civilization.
GrayMouser
Feb 27, 2009

Rank: not rated yet
"Left-handers also tend to have smaller body size, which is linked to less reproductive success..."

last I checked, 6'3" is not 'smaller.' Then again, I might just be an outlier.

I'm 6'1" and 2 of my brothers (also lefties) are 6'2" and 6'3". The shortest one in the lot is my right-handed brother at 5'10"...
Velanarris
Feb 27, 2009

Rank: not rated yet
"Left-handers also tend to have smaller body size, which is linked to less reproductive success..."

last I checked, 6'3" is not 'smaller.' Then again, I might just be an outlier.

I'm 6'1" and 2 of my brothers (also lefties) are 6'2" and 6'3". The shortest one in the lot is my right-handed brother at 5'10"...

Coincidentally, the smallest of the three among myself and my siblings is also the only right hander.
jonnyboy
Feb 28, 2009

Rank: not rated yet
I made up better fiction than this so called science, stoned at the age of thirteen. A collection of observations is not science, it is just a collection of observations.
rubberman
Mar 01, 2009

Rank: not rated yet
6'3 also lefty, two right handed brothers, 6'0 and 5'11. Of course I also have hyper mobile joints which most doctors beleive is detrimental to coordination yet I don't generally have issues when it comes to athletic practice.
HeRoze
Mar 04, 2009

Rank: 5 / 5 (1)
No need to get defensive. The article didn't say that all lefties are intelligent, short, homosexuals. Interestingly, none of the lefties are arguing against being more intelligent.
Velanarris
Mar 04, 2009

Rank: 1 / 5 (1)
No need to get defensive. The article didn't say that all lefties are intelligent, short, homosexuals. Interestingly, none of the lefties are arguing against being more intelligent.


Well here's your argument from a lefty, we're not more intelligent, we're more capable of absorbing information due to having to percieve things in both a left and right handed view. It's the same and more so with truely ambidexterous people. On average they are more capable at assimilation of new systems because they have to assimilate systems that are built for right handers while they are not right handed.
thales
Mar 09, 2009

Rank: not rated yet
Let's just say it: lefties are as gods among us.
Rank 3.6 /5 (13 votes)
Relevant PhysicsForums posts
  • Mitosis
    created1 hour ago
  • Stem cell question.
    created2 hours ago
  • Protease cleavage
    created9 hours ago
  • Pertubance in a model
    created15 hours ago
  • Cancer drugs and Alzheimer's, Oh my!
    created23 hours ago
  • Squishing cells
    createdFeb 09, 2012
  • More from Physics Forums - Biology

More news stories

The power of estrogen -- male snakes attract other males

A new study has shown that boosting the estrogen levels of male garter snakes causes them to secrete the same pheromones that females use to attract suitors, and turned the males into just about the sexiest ...

Biology / Plants & Animals

created 13 hours ago | popularity 4.8 / 5 (5) | comments 1 | with audio podcast

Grass to gas: Researchers' genome map speeds biofuel development

Researchers at the University of Georgia have taken a major step in the ongoing effort to find sources of cleaner, renewable energy by mapping the genomes of two originator cells of Miscanthus x giganteus, a large perenn ...

Biology / Biotechnology

created 10 hours ago | popularity 3.8 / 5 (5) | comments 0 | with audio podcast

Experts reveal how plants don't get sunburn

(PhysOrg.com) -- Experts at the University of Glasgow have discovered how plants survive the harmful rays of the sun.

Biology / Cell & Microbiology

created 13 hours ago | popularity 4.8 / 5 (4) | comments 0 | with audio podcast

Miami battling invasion of giant African snails

No one knows how they got there. But an invasion of African giant snails has southern Florida in a panic over potential crop damage, disease and general yuckiness surrounding the slimy gastropods.

Biology / Ecology

created 17 hours ago | popularity 4 / 5 (1) | comments 4

Protein libraries in a snap

(PhysOrg.com) -- A Rice University undergraduate will depart with not only a degree but also a possible patent for his invention of an efficient way to create protein libraries, an important component of biomolecular ...

Biology / Cell & Microbiology

created 17 hours ago | popularity 4.8 / 5 (4) | comments 0 | with audio podcast


Anonymous knocks CIA website offline (Update)

The website of the Central Intelligence Agency was inaccessible on Friday after the hacker group Anonymous claimed to have knocked it offline.

Google users warned of threat to smartphone wallets

Users of Google smartphone wallets were being warned on Friday that there is a way to crack pass codes intended to thwart thieves from going on illicit shopping sprees.

New error-correcting codes guarantee the fastest possible rate of data transmission

Error-correcting codes are one of the triumphs of the digital age. They’re a way of encoding information so that it can be transmitted across a communication channel — such as an optical fiber o ...

Complex wiring of the nervous system may rely on a just a handful of genes and proteins

Researchers at the Salk Institute have discovered a startling feature of early brain development that helps to explain how complex neuron wiring patterns are programmed using just a handful of critical genes. ...

Humans may have helped the decline of African rainforests 3000 years ago

(PhysOrg.com) -- Large areas of rainforests in Central Africa mysteriously disappeared over three thousand years ago, to be replaced by savannas. The prevailing theory has been that the cause was a change ...

New power source discovered

(PhysOrg.com) -- Researchers at the Massachusetts Institute of Technology (MIT) and RMIT University have made a breakthrough in energy storage and power generation.