Sure, less complex organisms evolve at a faster rate. In fact, the rate of evolution is really controlled by two (main) factors:
1. How fast new generations come along:
Of course, the more generations and the more mutations; the more that evolution is occurring. This explains why insects evolve so quickly - and why they're chosen for experiments.
2. How much evolving is even needed:
If you take jungle insects and put them in a desert (assuming they don't die within a few generations), they will very quickly evolve, however, if you leave them in the jungle, you won't see as many drastic changes. The crocodile is often referred to as the perfect predator because it has remained almost the exact same since the dinosaurs. Many species have come and gone but the crocodile persists. This is simply because, again, the crocodile is the perfect predator, it has no
need to evolve, so it doesn't (roughly).
how certain organisms came to be the way they currently are. — Susu
Yes, I love to think about Earth's amazing creatures. In fiction, we talk about other worlds and dimensions, and all the wonderful, mythical creatures that reside there. But I feel we too seldom appreciate the animals we have here. I mean we do. People love animals. But imagine if you came to Earth from another planet and saw a zebra, a giraffe, an anglerfish, a chameleon, or any of the countless other strange earthly inhabitants. It really makes you question how "mythical" a unicorn really is...
I'll also say, I'm really not qualified to talk about this evolution stuff, but it
is really interesting.