Full Idea
Quarks can change from one variety to another, and the top, bottom, charm and strange quarks all rapidly decay to the up and down quarks of everyday life.
Gist of Idea
Top, bottom, charm and strange quarks quickly decay into up and down
Source
New Scientist writers (Why the Universe Exists [2017], 01)
A Reaction
Hence the universe is largely composed of up and down quarks and electrons. The other quarks seem to be more important in the early universe.
Book Reference
New Scientist writers: 'Why the Universe Exists' [John Murray 2017], p.17