If you watched the recent Shogun remake, you might have wondered why the samurai, fearsome warriors that they are, had such goofy haircuts.

I'd asked a teacher about this when I was living in Japan. The two-part answer had to do with the helmets samurai wore in battle.

1. The top of the head was shaved for cooling purposes. Those helmets, made of thin iron plates, get hot.

2. The topknot, or chonmage, provided a raised contact point for the helmet at the rear of the head. The forehead provided a contact point at the front. This would friction-fit the domed helmet atop a samurai's head, while leaving a ventilation gap at the top.

I asked why the sides of the head weren't shaved as well, and the teacher said he wasn't sure. My theory is that hair on the sides provided additional friction to prevent the helmet from rotating in an impact. The samurai tied their helmets on with a cord beneath their chins, but just that and the topknot could surely use a little more help in battle; it's not like they had fitted foam inserts.

Another example of hair serving a function in a martial context:

Military service is mandatory in the Republic of Korea, a/k/a South Korea. When my cousin came of age in the '90s, he went into the ROK Navy. On a visit to Korea I met up with him while he was on leave, and was shocked at his regulation haircut: Shaved on the crown and all around the sides, but with long, emo bangs in the front! Essentially a reverse samurai haircut.

I asked him what the point was, and he explained that if they find you floating in the water, incapacitated or dead, they grab hold of the front locks to pull your body out. You were essentially growing a handle on the front of your head. Brutal but practical.