January 15, 2012

Evolution of left-handedness?

At Edge.org, Jonathan Gottschall offers a theory for why natural selection can't seem to make up its mind about left-handedness:
Which brings me to Charlotte Faurie and Michel Raymond, a pair of French scientists who study the evolution of handedness. Left-handedness is partly heritable and is associated with significant health risks. So why, they wondered, hasn't natural selection trimmed it away? Were the costs of left-handedness cancelled out by hidden fitness benefits? 
The scientists noted that lefties have advantages in sports like baseball and fencing where the competition is interactive (but not in sports, like gymnastics or swimming, with no direct interaction). In the elite ranks of cricket, boxing, wrestling, tennis, baseball and more, lefties are massively over-represented. The reason is obvious. Since ninety percent of the world is right-handed, righties usually compete against each other. When they confront lefties, who do everything backwards, their brains reel, and the result can be as lopsided as my mauling by Nick. In contrast, lefties are most used to facing righties; when two lefties face off, any confusion cancels out. 
Faurie and Raymond made a mental leap. The lives of ancestral people were typically more violent than our own. Wouldn't the lefty advantage in sports—including combat sports like boxing, wrestling, and fencing—have extended to fighting, whether with fists, clubs, or spears? Could the fitness benefits of fighting southpaw have offset the health costs associated with left-handedness? In 1995 Faurie and Raymond published a paper supporting their prediction of a strong correlation between violence and handedness in preindustrial societies: the more violent the society, the more lefties. The most violent society they sampled, the Eipo of Highland New Guinea, was almost thirty percent southpaw.

Think about throwing a spear at an animal you are chasing like a quarterback throwing the football while rolling out. Righthanded quarterbacks can throw better while running to the right than the left. (Indeed, Robert Griffin III of Baylor likely won the Heisman last year because, more than any other single play, a remarkable pass he threw that beat Oklahoma on national TV. After rolling to his left, this righthander surprised the defense by throwing a long bullet into the right corner of the end zone (video). Having a lefthander in your hunting party ups your chances that somebody will connect.
Many studies have since examined the Faurie-Raymond Hypothesis. Results have been mixed, but facts have surfaced that are, to my taste, quite decidedly ugly. A recent and impressive inquiry, found no evidence that lefties are over-represented among the Eipo of Highland New Guinea. 
It hurts to surrender a beloved idea--one you just knew was true, one that was stamped into your mind by lived experience not statistics. And I'm not yet ready to consign this one to the bone yard of lovely--but dead--science. Faurie and Raymond brought in sports data to shore up their main story about fighting. But I think the sports data may actually be the main story. Lefty genes may have survived more through southpaw success in play fights than in real fights—a possibility Faurie and Raymond acknowledge in a later paper. Athletic contests are important across cultures, and if we think they are frivolous we are wrong. Around the world, sport is mainly a male preserve, and winners—from captains of football teams to traditional African wrestlers to Native American runners and lacrosse players—gain more than mere laurels. They elevate their cultural status—they win the admiration of men, the desire of women (research confirms the stereotype: athletic men have more sexual success). This raises a bigger possibility: that our species has been shaped more than we know by the survival of the sportiest.

Here are the top ten baseball hitters of all time according to one measure where the average batter gets a 100:
Seven lefties, a switchhitter, and two righties. On the other hand, four positions in baseball: 2nd, short, third, and catcher are largely off limits to lefties because most throws wouldn't be cross body.

40 comments:

sabril said...

I recall reading somewhere that left-handedness is a lot more common in men than in girls. If so, it supports the hypothesis.

Matt said...

It's interesting given the reported connections between left handedness and dyslexia, schizophrenia, language impairments and creativity.

I mean, it seems like people tend to think there is a causal connection directly between left handedness and these things.

But perhaps people who have more successfully violent ancestors tend disproportinately to carry the heritability for left handedness, and that the life histories of their relatively more violent ancestors favoured creativity more and certain linguistic faculties less.

A tendency to a more violent life history might also explain some of the stigma towards left handedness.

Anonymous said...

Many of those lefty batters are only marginally lefty. A lot of them throw righty and, for that matter, golf righty. (As I do, for that matter.) Some do this because a coach or dad intentionally turned them around, knowing the advantage of being a lefty batter. But many of us just do it naturally.

Actually, I've spent a lot of time wondering why it seems natural for me to hit a ball in the air from one side and to hit a ball on the ground from another side. (And there are a lot of us. Lefty batters are reasonably common, even in Little League, where it isn't selected for. Lefty golfers are pretty few and far between.) I've also wondered how I'd bat in cricket, which seems to be about halfway between hitting a baseball and hitting a golfball.

NOTA said...

One thing seems likely to me, as an amateur: we're not really optimized for unarmed combat. We seem to be evolving toward less thick bone, and also, basically eveything we have that's good to hit someone else with is subject to being damaged in hard-to-fix ways by hiting anyone with it. Punch some guy in the forehead, you're liable to really mess up your hand. Kick him in the knee, and there are ample opportunities for broken toes. Both those have the nasty property that you might win the fight, but then not be able to properly hunt for weeks afterward, because you can't properly hold a spear till your hand heals up, you can't run worth a damn with a broken toe, etc.

My guess is that quite awhile ago, fighting for continued survival became something that almost always involved weapons, at which point the slightly thicker skull gave little help, and hitting someone with your fragile precision gripping instruments got replaced with using those instruments to hold onto the spear or club you're using to bash your opponent's brains out.

Anonymous said...

I figured this out watching Manny Pacquiao on youtube few months ago. It seemed so obvious.

Aaron in Israel said...

But when the children of Israel cried unto the LORD, the LORD raised them up a deliverer, Ehud the son of Gera, a Benjamite, a man lefthanded: and by him the children of Israel sent a present unto Eglon the king of Moab.

...

And Ehud came unto him; and he was sitting in a summer parlour, which he had for himself alone. And Ehud said, I have a message from God unto thee. And he arose out of his seat.

And Ehud put forth his left hand, and took the dagger from his right thigh, and thrust it into his belly....

Bill said...

It's all wrong regarding the lefty righty thing in baseball. Rather than confusion, it is simply much easier to track a pitch thrown from the opposite side. Lefty pitchers primary advantage is that they get to face a disproportionate number of lefty batters and are tougher on those lefty batters when they meet. In this lefty lefty matchup, the pitcher wins hands down.

A substantial number of batters throw right but bat left, again, to take advantage of the domination of right-handed pitching. It is much easier for a natural righty to learn how to bat left than to throw left.

Of the lefty (or switch) batters on your list, Mickey Mantle, Ted Williams, Joe Jackson, and Ty Cobb all threw right. Ruth threw left, but signed his autographs right handed.

The lack of lefty catchers is a puzzle. There is no clear problem throwing, except perhaps throwing over the pitcher rather than to his left on steals.

Anonymous said...

Whatever the merits of the Frenchmen's theory, I'm not sure the dominance of lefty batters captures the idea. It's not the weirdness of lefty batters that makes them so good; it's the fact that they usually face righty pitchers.

The advantage here revolves around ball movement. Hitters like to face opposite hand pitchers because their balls break toward them. (If facing the unusual trumped this, then righty and lefty batters alike would do worse against lefty pitchers because they are far more unusual than righty pitchers. But they don't. Lefty batters do way worse against lefty pitchers but righty batters do better against them.)

The vast majority of pitchers are righties, so the vast majority of top performing hitters are lefties.

If you want to confirm the fighting theory, you should look at boxing and MMA and see if lefties are more common in those than in general society. I'm not a huge boxing fan but I don't get the sense that lefties are all that common.

ironrailsironweights said...

In the elite ranks of cricket, boxing, wrestling, tennis, baseball and more, lefties are massively over-represented.

Boxing is definitely an example of over-representation. Out of Boxrec.com's list of the top five boxers in each of the 17 weight classes, a total of 85 boxers, 25 fight left handed (29.4%).

Peter

Anonymous said...

Lessons of Libya

David F. said...

In Judges 3:15, the Bible draws attention to Ehud's left handedness, which seems to have aided him in making a surprise attack on the king Eglon.

Anonymous said...

I remember hearing that left-handed people had a higher standard deviation in intelligence, and were thus overrepresented among the most intelligent. Has anyone heard a similar argument, or know of any data one way or the other?

Kiwi said...

If you know your Bible, you'll remember two stories of the effectiveness of left-handed fighters from the Book of Judges:
-- the story of Ehud son of Gera, who stabbed the King Eglon of Moab to death -- he hid the short-sword on his right thigh, where Eglon's guards were not expecting it (i.e., they would check the left thigh for a weapon, expecting a right-handed swordsman).
-- the battle of Gibeah, where the tribe of Benjamin, whose army was based around 700 left-handed slingers, was able to inflict massively disproportionate casualties on the other tribes of Israel.

Maybe an explanation of Gottschall's theory?

bbartlog said...

Interesting... but how does this explain the phenomenon observed in modern societies where left-handed men have more surviving grandchildren, while left-handed women have fewer? I'd want to look at other correlates of left-handedness and then see whether there are any brain structure effects that modern technology can detect.

Neil Templeton said...

Maybe part of lefty success in athletics is due to a reduced propensity for analytical thought. I believe lefties tend to "streamline" the decision process. If true, this may provide some advantage in athletics and other straight-forward action events.

Shawn said...

Are you still doing VDARE? Missing your stuff...

Anonymous said...

If this explains left-handedness, then why isn't it roughly 50-50 in all societies? Is there a disadvantage to being left-handed, or some reason why societies would gravitate toward everyone preferring the same hand?

Lugash said...

I am Lugash.

W.r.t baseball, do pitchers get coached or trained with how to deal with left handers? If not, you'd think this would be a moneyball type of situation.

I am Lugash.

Anonymous said...

"W.r.t baseball, do pitchers get coached or trained with how to deal with left handers? If not, you'd think this would be a moneyball type of situation."


the advantage is simply inherent; it's not the same thing as boxing or fencing.


it's just easier to hit a pitcher who is delivering from the other side. you see the ball better.

agnostic said...

Here's a free copy of the article on homicide rates and left-handedness, and a graph of the relationship:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1634940/

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1634940/figure/fig1/

Only 8 societies studied, and most of the relationship is due to the top 2 or 3 having much higher left-handedness. Doesn't seem to be much variation in left-handedness among the rest, while they vary a lot in homicide rates.

2 of these exceptional groups are in New Guinea, so that some confounds are taken care of, but they show the opposite relationship: the Eipo have less homicide than the Jimi valley people, but have twice as many left-handers.

The idea is neat and promising, but there aren't enough groups with high left-handedness to make the pattern look strong.

agnostic said...

Also worth remembering that selection for the kind of violence they're talking about is recent and mostly confined to horticulturalist societies, where men do nothing but beat each other up and raid for wives.

The hunter-gatherers, agriculturalists, and the merchant caste in their review all had low left-handedness. It was the Amazonian and New Guinean gardening groups who had lots of lefties.

It would be interesting to see where pastoralists stand.

Anonymous said...

Steve,

I think some of your readers are missing that the Frenchman's theory was mostly consigned to the dustbin as a leap too far and he was proposing that left-handedness reveals the "survival of the sportiest".

Anonymous said...

The Death of Protestant America: A Political Theory of the Protestant Mainline

sideways said...

" do pitchers get coached or trained with how to deal with left handers? If not, you'd think this would be a moneyball type of situation"

Yes, but pitchers at the pro level are told how to pitch to each batter as an individual anyway.

Anonymous said...

Think about throwing a spear at an animal you are chasing like a quarterback throwing the football while rolling out.


I don't see the point. The animal you're trying to kill does not care whether you are left-handed or right-handed.

And the defense in football likewise does not care.

Now, in some other sports, such as baseball, there is an advantage to being left-handed. But this does not extend to all areas of physical endeavor.

Anonymous said...

N-scare more hysterical than the Red Scare.

hbd chick said...

there are some neat castles with left-handed staircases in great britain (examples here and here) -- the owners clearly had an advantage during a sword fight on the staircase a la errol flynn.

jody said...

i've commented on this topic a lot over the years here. of course, there's plenty to think about, and this is a new angle on the subject. but for now, i definitely think baseball is totally irrelevant. especially the batting part of baseball.

baseball has existed for 100 years, tennis 100 years, and cricket maybe 200 years. hitting a small, high velocity, incoming ball with a club just has absolutely nothing to do with the 100,000 year evolution of throwing and / or handedness.

that's something which never happens in nature, never happens in a fight, never happens in war, and never happened before in sports either, before those sports were developed. this isn't a star wars movie. you don't deflect incoming missiles. you dodge, avoid, or block them. after they start flying at over 200 feet per second, the only thing you can do is block with a shield or take cover.

i mean, you would want to study throwing baseballs, not batting baseballs. that's for starters. there's throwing and hitting targets with balls in most ball sports. cricket, american football, baseball, basketball (they're called free "throws" for a reason) and the field part of track & field all have throwing stuff with your hand at targets. ice hockey and soccer and golf have launching objects at your feet at targets.

in fact, it's probably good to start listing how fast various objects move, and a human's ability to visually track them coming in or going out. for instance, a baseball flying at 100 miles per hour is moving at about 150 feet per second. a tennis serve at 150 miles per hour is moving at about 220 feet per second. a crossbow bolt flies at about 350 feet per second. and a slow handgun bullet is moving at 900 feet per second.

jody said...

as for the hand to hand hypothesis, i think that's wrong. forget hand dominance - humans have thumbs. they pick stuff up. they don't fight hand to hand when they fight for keeps. they fight with weapons. and they don't train. the average human never trained to fight a day in their lives. pick up a club, hit the other guy over the head, the end.

the only evidence i would accept would be stuff life, in large army versus army engagements before bows, did left handed guys survive at a higher rate? i'm guessing no -that stuff was just chaos. hack and slash brawling. there were no rules that created the kind of "fair fight" conditions giving left handers an advantage over right handers in one on one combat sports.

handedness does matter in boxing and kickboxing, but i don't think it has any effect on modern real wrestling run by FILA, or the various forms of wrestling around the world. wrestling is pretty big, and most places have their own version. japan has judo, sumo, and jiujitsu. the US has folkstyle, which is different than FILA freestyle or FILA greco. there is even wrestling in africa, in senegal, which has a (real) wrestling league as a spectator sport.

and as MMA shows, real unarmed fights are more like wrestling than boxing or kickboxing, and handedness doesn't matter much in rough and tumble, no rules fighting.

Tom Regan said...

What percentage of left handers are sportsmen/women? Are they over-represented in sports? Perhaps yes, but only to a small degree.
Where they are much more noticeably overrepresented is in the visual arts and music. The theory there is that left-handers are more guided by the right side of the brain, the dreamy and creative side, while righties are guided by the left side, the logical and calculating side.
The theory would still hold true with artists - that they achieve high status through their feats and thus pass on more genes.

J said...

In the Illiad, the winners of the Greek army's funeral games were awarded weapons, pig iron, gold tripods, and slave girls. The champions were mostly interested in weapons, Ajax kills himself because they were awarded to someone else and he got only the girl.

Anonymous said...

"the only evidence i would accept would be stuff life, in large army versus army engagements before bows, did left handed guys survive at a higher rate? i'm guessing no -that stuff was just chaos. hack and slash brawling."

Shields in tight formation so i'd say the opposite would have to be true. It'd have to be earlier more solo combat i think.

Left handedness and MAOA?

Sinister indeed :)

Anonymous said...

Re: lefty catchers. Because most batters are right handed, a lefty catcher has to deal with a greater percentage of batters in the way when making throws down to second base during a steal attempt. Lefty catchers making it to the majors, like Mike Squires, had a sort of side step in their throwing motion to avoid the batter.

barfbreath said...

@ Bill - There is a reason why lefty catchers are undesirable. It has nothing to do with the throwing process. Rather, it has to do with the process of tagging incoming baserunners. When tagging a baserunner, it is generally beneficial to allow the baseball to travel through the air for as long as possible before catching it and applying the tag. By catching the ball with your left hand, you will be able to quickly "slap" a tag, rather than shoving the tag across your body. For this same reason, it is much more desirable to have lefty first basemen. It is much easier for them to slap a tag on a pick-off attempt at first base.

CJ said...

I'm somewhat ambidextrous, but better with my left hand at most things. When I played baseball, I owned left and right handed gloves and used both in scrub ball, but in competition I always threw left and always played first base or right field. I hung out at the diamond a lot and sometimes filled in as a practice catcher. When I did I absolutely had to play right-handed, even though this was just practice (for pitchers and BP) because catcher's mitts that fit on the right hand (so that you can throw left) didn't exist. As far as I know, they still don't, unless maybe you special-order them.

It doesn't really make sense to me that left-handed catchers are so rare, but hey, there just aren't any out there.

BTW, in spite of my own sinistrality I consider left-handedness to be a handicap, a deviation, and cheer for other lefties as for the underdog. It may not make sense to some, but this is how the same person could cheer Tim Tebow and Michael Vick.

AYY said...

Anyone know why are there so many right hand throwers and left hand hitters in the majors? The dominant hand is the top hand on the bat, so it would seem that right hand throwers and left handed batters would be using the hand that they have less precise control over as the dominant hand, What am I missing?

barfbreath said...

@ AYY - I think it is misleading to label either hand "dominant". The bottom hand generates power, while the top hand is responsible for DIRECTING the whip of the bat. If you listen to a good power hitter talk about his swing, he will often use terms like "pull the knob through the zone", whereas contact hitters are more concerned with the top hand. For this reason, righties will generally generate more POWER from the left side of the plate (this does not mean they are better all-around HITTERS from the left side).

Consider switch hitters. Mark Texiera, for example, throws righty, but has much more power from the left side. He does; however, strike out much more as a lefty. From the right side, he strikes out much less (because his "dominant" hand is now controlling the bat path rather than generating power). As a right handed batter, he has less power. Same story with Nick Swisher...

AYY said...

Barfy,
Thanks, I guess it's one explanation for why righties can effectively bat lefty but then why do few lefties bat righty? I still would like to understand why there are so many lefty hitters in the majors.

Anonymous said...

You're closer to first base, and you're follow through carries you towards first.

Anonymous said...

Aren't really good athletes more likely to be slick with both hands? And more liable to experiment with using just one, maybe playing to the right, maybe using their weak hand because it makes for a challenge?