Understanding Metal!

I had an odd phone call from someone looking for guitar lessons a few years back. Occasionally I would run an ad in the paper and it led to some interesting conversations. This fellow wanted to improve his technique and upon questioning I learned that meant fast scales. He wanted to learn how to play scales really fast. Nothing wrong with that, but he seemed a bit obsessive about it so I asked "why?" I followed that by saying that fast scales were just about the most boring thing on earth, musically. He seemed nonplussed by that so I next asked what kind of music he played. The answer, "death metal." I told him I didn't think I was the right teacher for him!

But just what the heck is "death metal"? Is it more deadly than other forms of metal? What makes something "heavy metal"? At last, there is a clip on YouTube that explains all. Here you go, ten genres of metal demonstrated in three minutes:

Just in case you missed one, here are the ten 'genres':

1. Glam Rock
2. Heavy Metal
3. Power Metal
4. Folk Metal (or perhaps, "Celtic Metal"?)
5. Black Metal
6. Death Metal (aha!)
7. Thrash Metal
8. Melodic Death Metal (heh, heh, heh)
9. Progressive Metal
10. Metalcore

The guitarist who did this, a fellow named Raz, used the term genres. I guess that's fair enough, if that's how the players and listeners think of it. Assuming that this is an accurate portrayal of the different kinds, then I have to say that pretty much any sixteen bars out of a piece by Beethoven contains more musical variety. Is it really true that small modifications to a rhythmic pattern, or to the articulation of the harmony can result in an entirely new 'genre' nowadays? There was a time when it took more than that just to write one of a set of variations. Here, see what I mean. This is the first movement of the Piano Sonata in D minor, op. 31, no. 2 by Beethoven: