The point about overhand being more tiring doesn't take into account that people fought for only 15 seconds or so at a time. I'm wondering about how spartan hoplites were depicted as fighting with the first row underhanded and the second overhanded on the History Channel. If that really happened, you wouldn't have peoples arms bumping into each other.
Hoplite battles would either last a very short time, or a very long time, from my understanding. Much longer than 15 seconds.

That's called "physical conditioning". "Evolution" has entirely different meanings.
Evolution has more than one meaning. Most generally, it means 'to change'.


Anyway, I can't imagine how using a spear underarmed would be harder to control than overarmed. I think it would be easier to hold a spear farther to the back when fighting underarmed, though you would have to worry about balance with both methods. I'd be worried about hitting the guy behind me in the face fighting overhanded. Perhaps that's something they were able to deal with in training.

You do, of course, have to take the close formation into account. An 8ft can be a liability if held the wrong way. Some have said overhand is ideal in this case. I don't know. The people who said the front rank fought underhand(to reach the opposing front rank) and the second rank fought overhand(to reach farther) sounds sensible, if I try to imagine it. Especially if you take into account, as the essay writer did, that hoplite armor did not include protection for the underarm.