One Seed, a Thousand Branches

Rock started as a single thing in the 1950s, but by the 1970s it had splintered into subgenres that barely sounded related. Hard rock (Led Zeppelin) cranked the volume. Progressive rock (Yes, Genesis) added classical complexity. Glam rock (Bowie, T. Rex) added theatricality.

The fracturing accelerated through the decades. Punk stripped rock bare. New wave added synthesizers. Thrash metal sped it up until fingers bled. Shoegaze buried it under walls of reverb. Math rock added irregular time signatures.