The Cambrian Explosion shows that life can do all sorts of divergent things. The similarity of many current life forms (e.g. fish that are totally unrelated but

The Cambrian Explosion shows that life can do all sorts of divergent things. The similarity of many current life forms (e.g. fish that are totally unrelated but work about the same) has more to do with environmental pressures producing similar results, that it has to do with what's possible?