What's All This "Why?" Stuff, Anyhow?

Sept. 7, 1999
Why did primitive man learn to walk on two feet? I heard a lecture by a guy at the University of California at Berkeley, Professor Vincent Sarich. He has a good theory about the reasons and...

Why did primitive man learn to walk on two feet? I heard a lecture by a guy at the University of California at Berkeley, Professor Vincent Sarich. He has a good theory about the reasons and incentives that primitive man would thrive on when standing on two feet.

When a baseball pitcher is delivering a fastball, he must let go of the ball at exactly the right time. And how precisely must that time be programmed? Is it more or less than a millisecond? Don't be silly! How can a guy have a precision or uncertainty for timing the release of a thrown object when it's less than 1 millisecond? Hmmm....

Well, a guy who can throw a baseball and hit the strike zone and the correct corner thereof with a precision of ±3 in. is called a major-league pitcher. He can earn a few million dollars a season for several years. I admit, that's NOT a bad way to make a living. And he has learned to release the ball with a precision of as small as 100 µs—just one tenth of a millisecond.*

But think about this guy's ancestors. Some of them could throw a rock with the same kind of precision. That skilled thrower could bust the hell out of the head of a skulking tiger, or maybe knock him out, with a well-aimed rock. Just when the tiger thought he was at a safe range!

Think of the incentives: The guy who could do that survived, and the guy who couldn't got eaten by the tiger (perhaps). So there is one incentive that may have been very helpful for early man. It may have been a useful trait for survival a couple hundred thousand years ago. Meanwhile, to this day, apes and other modern-day primates are only capable of a release with an uncertainty of about ±5 ms. So throwing stones was not their main mode of defense. As the old saying goes, "Choose your parents wisely." Or your ancestors.

The timing for little David to let his sling loose in order to nail Goliath between the eyes was comparably precise. Even though we do not know exactly how long David's sling was, he had to have had pretty good timing.

Now, let's say you are a caveman who threw a 90-mph rock at the tiger and MISSED. What do you get then? You probably get a broken rock, which can easily have a sharp edge or two. And that rock's sharp edge may be useful for dismantling the tiger after you have managed to stun him with another rock. So Professor Sarich has managed to show some nice correlations between the process of learning to stand on two feet and the process of defending one's self against ferocious critters. That correlation sounds good to me. It's a pretty good theory. I can't prove it, but I LIKE it.

Earlier today, as I was hanging around at Chicago's O'Hare airport, I was reading about a theory that some cavemen (I apologize for the imprecise term) were skilled at breaking rocks into sharp edges. These guys would, in theory, pick up a rock and whack it against a big stone. On the first bang, they could tell if this rock had good promise. Then they would try to break it into some good blades. But if their judgement said it would likely make a POOR edge, they would flip it away.

Well, some archeologists have found a number of these REJECT rocks that were just tried once, and then thrown over the shoulder, so to speak. They have checked out the stress marks that early man used to TEST the rock hundreds of thousands of years ago. These rejects were found amidst the debris of other edge-making scraps of rock. So maybe some of these old theories are not so dumb, after all??

Can I throw strikes? At any speed? Rarely. And certainly not over 40 mph. Can I whack a golf ball with good range and good angular accuracy? Maybe; I've never tried.

Can I put a hook shot in the basket? Release over my head while I am looking cross-eyed at a defender? Sure, about 1/40 as often as I can throw a baseball into the strike zone. The tigers woulda got ME a long time ago if I did not have better TOOLS.

All for now. / Comments invited!
RAP / Robert A. Pease / Engineer
[email protected]—or:

Mail Stop D2597A
National Semiconductor
P.O. Box 58090
Santa Clara, CA 95052-8090

*Computations: If a ball at the end of your arm, at a radius of 3 ft., is moving at 90 mph or 132 ft./s, it will change its ANGLE by 0.0044 radians, or 0.252°, every 100 µs. And an angle of 0.0044 radians corresponds with an uncertainty of 6.4 in. (±3.2 in.), after the ball—or rock—has gone 60 ft.

Don't tell me, "60 feet and 6 inches," because the pitcher's release is likely to be a few feet IN FRONT of the pitcher's rubber—so long as the pitcher does not step off the rubber.

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