Some Observations and Questions on Handedness

Humans have had a long and storied relationship with tools. From rocks and sticks to pocket knives and sonic screwdrivers, we have depended on tools to make our lives easier and more efficient. But a recent study shows that our use of tools might also have a lot to do with how we use our hands. A study from the University of Sussex shows that our (humans’) penchant for right-handedness has a lot to do with what part of our brain thinks about how to manipulate tools. Our left hemispheres do most of the heavy lifting when it comes to how we interact with tools. This is how humans and their close cousins came to be right-hand dominant species. This also could help explain how humans developed speech, as the constant working of our left hemispheres — the side responsible for speech — caused them to get stronger.  However, the study shows that this dominance only manifests when the subjects were dealing with inanimate objects. When dealing with animate objects — like other animals or themselves — no real dominance was shown.

There are a lot of studies about handedness in humans — how it affects their personalities, relationships, careers, etc. From what I found, there really aren’t many on just how many people are left-handed. Perhaps that has to do with the fact that they don’t pass out a lot of grant money for just counting stuff. However, there seems to be a general consensus that about 10% of humans are left-handed. By left-handed, of course, I mean left-hand dominant. Many people fall somewhere in the middle along the Edinburgh Handedness Inventory.  I’m right-hand dominant, and very much so. I do everything I can think of as a righty, though I’ve been told I sweep like a lefty when curling. I know many people, and you may too, who switch it up, though. They may write and eat left-handed, but throw and bowl and play pool right handed. They may use their right to pick up the phone, but their left to open a door. Again, a lot of it comes down to what we’re interacting with. This is the point when I talk about actual baseball.

This started — like a lot of baseball writing, trust me — with an incorrect hypothesis. It seemed to me that there were less switch hitters than there were even a few years ago. So I ran the numbers, and I was wrong. Pretty badly wrong. So I expanded it out a little. I looked at the percentage of plate appearances that went to batters that the Retrosheet database defined as switch hitters from 1961 to now, commonly known as the expansion era.

This is more interesting. It seems as if there were very few switch hitters in the early 60s, and their heyday fell between the mid-80s and mid-90s.  They’ve tapered off a bit since then, but are still in higher numbers than even the early 80s. So, if all these plate appearances are going to switch hitters, from whom are they taking them?

It looks like they are taking them from right-handed hitters. In fact, there has been a pretty steady decline in right-handed batters since 1961, an almost 12% drop in fact. But why? If 90% of the population is right handed, why do right-handed batters only get half of the plate appearances? Are there just fewer righties in the league? Well, maybe.

Available data does not include what hand a player defines as their dominant hand. We can only deal with game data. Because of this, we have to make some assumptions. One of those assumptions I’m going to make is that the hand a player uses to throw is their dominant hand. It seems like a fair assumption, accounting for all but the truly ambidextrous. With that in mind, there seems to have been a slight drop in overall righties in the league.

But that’s only about a 5% drop, so it must be something else. Perhaps this is an indication that more naturally-right-handed players are focusing on switch hitting or hitting lefty. This makes a little bit of sense. Right-handed pitching has seen a bump over the past 20 years or so.

So it seems reasonable that GMs and managers are looking for players that can hit from the other side. However, right-handed throwers — that is to say, players that catch with their left hands — are still preferred or required in many positions such as third base, shortstop, and catcher. So a righty that can hit lefty might have an advantage.

Since 1961, pure right-handers have been in decline while right-handers who can hit from the other side have risen — though the exact way this hashes out has fluctuated. Are righty-righty players discriminated against? Do righties who can hit from the other side have a better shot of reaching the big leagues? Are young right-handers being taught to hit switch or lefty to help their chances in getting drafted or getting a scholarship to college? These are all questions I don’t have answers to, hence the title of this article. But it does seem that baseball players are continuing to break their natural inclination to use their right hands to manipulate tools. But is batting “left-handed” even a pure form of left-hand dominance? I mean, both hands are on the bat. Is it easier to get a right-hander to bat from the other batter’s box than it is to, say, teach them to write or eat or throw left handed? Man, it’s days like today I wish I were a neuroscientist.

The truth probably lies somewhere in the middle of all these questions. Natural lefties may be looked on more favorably. Natural righties may be learning to hit left handed. This issue — like a player’s clubhouse contributions or a managers true effect on a team — deals with sociology, psychology, and biology in a way we can’t boil down with simple game data. Maybe humans are evolving into some super race that can use both hands at will, and baseball is at the forefront. Or maybe the fact that we don’t make anything by hand anymore has led to a reduced need to rely on our left hemispheres. Whatever the case, we can put this in the bin where a lot of baseball research goes. We know that something is happening. We’re just not sure why.