So, Has Handedness Changed at All?

Sometimes I just like to mess around with data to see if I find something. Today was one of those days. Two years ago, Perri Klass wrote in The New York Times, “The percentage of left-handers in the population seems to be relatively constant, at 10 percent. And this goes back to studies of cave paintings, looking at which hands hunters are using to hold their spears, and to archaeological analyses of ancient artifacts.”

So I wanted to figure out whether handedness had changed at all in baseball. Are there more southpaws or switch-hitters in baseball now than there used to be a decade ago, or half a century ago?

I took a look at all seasons from 1920 to 2012, and took a look at every player active in baseball in each season: just lefties and righties among pitchers, but including switch-hitters among batters. (I wasn’t able to include Pat Venditte.)

Among pitchers, you can see that the proportion of lefties climbed from the 1930s through the 1960s, but in the expansion era, it has remained pretty stable at about 78 percent righty, 22 percent lefty. (The absolute minimum was in 1939, when just 16.3 percent of pitchers were lefties.)

batting

The post-1970 average has been 78.5 percent righty, 21.5 percent lefty; the average of 2011-2012 was 78.6 percent righty, 21.4 percent lefty. Like I said, stable.

So what has it been like for the hitters? A bit more volatile. Switch-hitting was on a steady rise from the 1930s to the 1980s, finally tailing off in recent years. Judging by the fact that both righties and lefties were downward-sloping from about 1930 to 1990, it seems that both natural lefties and natural righties were becoming switch-hitters.

That makes some sense, considering the stability in the proportions of pitchers of each handedness. (If a lot more lefties started coming into baseball at a certain point, you wouldn’t expect as many natural right-handed hitters to start switch-hitting.)

pitching

So, what does this tell us? The rough proportion of lefties and righties is still pretty similar to what it was 90 years ago, and the proportion of lefty pitchers in baseball is about twice as high as it is in the population.

It’s a bit harder to tell when it comes to batting, because there are so many people who either switch-hit or hit with a different hand than they throw with, like Rickey Henderson, or Randy Johnson, or youth hockey-playing Canadians like Justin Morneau or Corey Koskie.

Evolutionary selection for lefties is clearly stronger in baseball than it is in nature. Scientists are still trying to figure out the reasons for lefties’ low relative prevalence in nature.

But it’s obvious why they exist in baseball. I mean, just look at Jamie Moyer.




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Alex is a writer for FanGraphs and The Hardball Times, and is a product manager for The Washington Post. Follow him on Twitter @alexremington.


33 Responses to “So, Has Handedness Changed at All?”

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  1. Marty says:

    Yes, but how many of those lefty batters do everything else righty? I know that I throw better lefty, but am right-handed dominant with everything else.

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  2. David says:

    Greg Harris is angry you didn’t give him a special purple dot in 1986!

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    • Oh, cool — I actually didn’t know about Greg Harris! I should mention that, among the batters, there were two uncoded data points in 1925 and 1926. I’m not sure who it is, but it is very possible that it is the same person.

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  3. Matt says:

    Nice. Surprised I hadn’t seen something like this before.

    I’ve always wondered why left-handed pitchers seem to be able to get by with weaker stuff. Maybe that’s a perception thing and not reality, but if it’s true it’s a little counterintuitive, since they’re giving away the platoon advantage much more than right-handed pitchers.

    The only thing that could make it make sense is if everyone, including RHBs, is worse against a lefty relative to an equally-stuffed righty.

    What does make sense is that you see a lot more left-handed hitters who have a particular problem hitting against same sided pitching. With the population of RHPs so high, almost all RHBs who make it have to be able to hit them. But LHBs can fake their way through by killing RHPs as they climb the ladder.

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  4. Luis Matos says:

    “Has handedness changed at all?” is a perfectly fine title by itself.

    I like the article though.

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  5. byron says:

    It’s been explained to me, but I’m still mystified by the hockey-related hits left throws right phenomenon. I played hockey from 6 and older, and played baseball from 7-10 (and wish I’d kept with it). I did it all right handed because why wouldn’t I?

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    • Llewdor says:

      Fundamentally, it’s because Canadian kids are taught to hold the stick like that. Why they’re taught that doesn’t really matter, but that they are is why they tend to bat left-handed.

      The reason Canadian kids are taught to hold the stick with their dominant hand at the top is to grant better puck control. If you think about it, aside from slapshots, the lower hand isn’t doing anything other than acting as a fulcrum, so why would you waste your dominant hand there?

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      • Jon L. says:

        I don’t agree at all. The lower hand controls the stick and supplies the power, while the top hand just holds it steady. It’s like saying righties should write with their left hands, so their dominant hands can do the real physical labor of pinning the paper to the desk.

        But then, I’m not Canadian.

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    • Aaron says:

      My Dad always said he was taught to shoot left because most people naturally shoot right, so you were automatically more useful as a lefty.

      I’m not sure whether the fact that most Canadians shoot left dispels or proves that theory, of course.

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  6. Sogard's Optician says:

    I was a youth hockey and baseball playing American. I write Righty, I threw R, batted L, shot hockey L.

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    • Blofkin says:

      Us lefties are all a bunch of weirdos. Hockey and bat lefty, write lefty, left hand dominant but I kick and throw righty.

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  7. gnomez says:

    I remember reading about a LH pitcher a few years back who was naturally right-handed, but can’t remember who it was. For some reason I want to say he was with Toronto, but the name escapes me.

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    • El Vigilante says:

      Throwing is the only thing Hyun-jin Ryu does left-handed. His father bought him a LH’ed glove (one that goes on the right hand) when he was 10, and in response, Ryu learned to throw left-handed.

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    • Matt says:

      Billy Wagner

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      • TKDC says:

        Yeah, I believe he broke his arm in high school, and then learned to throw with his left. I also heard a story about how he used to only have one baseball and he would throw it as far as he could, run get it, and then throw it again.

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  8. AC of DC says:

    Probably most enjoyable to me was the notion that prehistoric cave painters were reliably concerned with true-to-life accuracy at a rate not seen in artists in recorded history since. (“No, no, Ug, him hold spear nearer to top for better control.”*)

    Then again, I don’t go for that lazy Modern Art stuff, anyway. Have you seen some of those cave paintings? A six-year-old kid could do that!

    *All cavemen had names like ‘Ug’ and spoke broken English. Look it up.

    Oddly, when I first came to hockey (casually), I naturally handled and shot lefty — until someone told me that as a right-handed person, I should be doing it the other way. And then it didn’t matter ’cause I opted for goalie. And now both you and the world are a few seconds older than you were before you read this, but only one of you is any wiser.

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    • Jason says:

      I’m guessing the analysis was of the artists themselves. You can tell if a painting was done by a right of left handed artist and if you analyze hundreds of paintings you can estimate handedness of the population. Counting which hand a spear was depicted in would be much more problematic.

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      • Jason says:

        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%.

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        • Baltar says:

          Ha! This proves that lefties are twice as likely to be artistic. Or does it prove that there were twice as many lefties in 30,000 BC?
          All kidding aside, thanks for the information.

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  9. larry bird says:

    Is there some sort of test you can do to tell which hand is dominant?

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  10. djmax101 says:

    I learned to throw (and still do throw) right handed because my family already had right handed gloves, despite being a natural lefty. Still bat on the left typically.

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  11. Mr Punch says:

    LHPs have an advantage throughout the development process because they’re unusual; this advantage presumably decreases at higher levels, but does not disappear – a LHP can still get by on “junk” more readily than a RHP. At least a few pitchers reverse their batting stance to avoid exposing their throwing arm. On the other hand, there are four fielding positions (C, 2B, 3B, SS) where a player almost has to throw right, and another (LF) where it may be preferable to throw right.

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  12. I should have mentioned this at the top. All data comes from baseball-reference.com.

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  13. Word says:

    A related piece (from a year ago) of some potential interest:
    The Decline of Left-Handed Batters

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