Playing Rounders

A worn-out baseballThere are three That’s a Fact videos to catch up on. The first, Throwing a Strike, appears to be on the least interesting topic. Here’s a transcript:

Summertime in the US can mean a few things: grilling outdoors, road trips, and of course baseball. Great pitchers make throwing a ball look easy, but there’s a lot more to it than you might think. It all starts in the premotor cortex of the brain, where thousands of plans are stored, plans that coordinate whole groups of muscles. Those plans go to the motor cortex. They also go to the cerebellum, which is like a gatekeeper which sorts out data from the tendons, muscles, eyes, ears, and skin.

I had been intending to give you the whole thing entirely without comment, but that was before I encountered a Mystery. You see, during this last sentence an animation plays of some kind of primitive computer screen displaying scrolling lines of code. A quick search turned up Mendel Cooper’s Advanced Bash-Scripting Guide (subtitled “An in-depth exploration of the art of shell scripting”) as the source of the code, specifically from an example of a random number generator. I put to you: Why? And what can it mean, in the context of “a gatekeeper which sorts out data from the tendons, muscles, eyes, ears, and skin”?

These three parts of the brain – the premotor cortex, motor cortex, and cerebellum – work together. They provide continuous information through the spinal chord and thousands of microscopic nerves to the muscles. Data gathered by the eyes help judge distance. Tiny adjustments are made to the arm, wrist, fingers, and even the torso and feet, so that everything moves in exactly the right way at exactly the right time. When the brain signals for the ball to be released the force imparted to the ball pulls it out of the hand at just the right moment so its trajectory is right on target.

Some stock sound effect calls out “strike” at around this point, presumably because the impeccably well-aimed ball was nevertheless missed by the unintelligently designed batter and instead caught by the catcher behind him.

All that work and that fast for just one pitch. God designed our bodies and minds so complex that its no wonder that the psalmist of the bible declares you are “fearfully and wonderfully made”.

…to pitch baseball?

Anyway, I hope you enjoyed that superficially in-depth yet ultimately meaningless, and overly mechanistic explanation. Since the video was released an article by Brian Thomas called Why High-Speed Throwing Is Uniquely Human has been published, about a recent paper in Nature, Elastic energy storage in the shoulder and the evolution of high-speed throwing in Homo. A better discussion of the paper can be found at John Hawks’ blog and elsewhere, but I bring this up because of how Thomas works in reference to the above-mentioned video in his article:

The Nature study did not mention that each of these anatomical features requires precision control by the nervous system, as a recent That’s a Fact video highlights.

So much for the verifiable science, which describes how throwing works so well in humans. In exploring why humans have anatomy fine-tuned for throwing, the Nature authors departed from the known to tell a tentative tale.

The implication is that this That’s a Fact video is somehow more detailed than the paper, which is hilarious in the light of paragraphs like this one:

Throws are powered by rapid, sequential activation of many muscles, starting in the legs and progressing through the hips, torso, shoulder, elbow and wrist. Torques generated at each joint accelerate segmental masses, creating rapid angular movements that accumulate kinetic energy in the projectile until its release. It has been shown that internal (medial) rotation around the long axis of the humerus makes the largest contribution to projectile velocity. This rotation, which occurs in a few milliseconds and can exceed 9,000° per s, is the fastest motion that the human body produces. Although previous research has focused on the internal rotator muscles of the shoulder, these muscles alone cannot explain how humans generate so much internal rotational power. Calculations of the maximum power-production capacity of all of the shoulder’s internal rotator muscles indicate that these muscles can contribute, at most, half of the shoulder rotation power generated during the throwing motion. Peak internal rotation torque also occurs well before the humerus starts to rotate internally. Furthermore, variation in muscle fibre orientation in these muscles produce actions other than internal humeral rotation that reduce power output for this action. [References omitted.]

The authors may not have talked much about the neural system, being more concerned with the role of the muscles and bones directly, but you can hardly accuse them of not doing “verifiable science” or describing “how throwing works so well in humans.” In contrast, the more evolution-related discussion is relatively limited, when compared to the bio-mechanics.


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