Consider a fine organism like me, the tapeworm—less complex over time, asexual reproduction, streamlined for survival:

Hatch.
Eat. Shit.
Eat. Shit.
Eat. Shit.
Eat. Shit.
Eat. Shit.
Eat. Shit.
Eat. Shit.
Eat. Shit.
Eat. Shit.
Eat. Shit.
Eat. Shit.
Eat. Shit.
And Die.

Tremble before me monkeys! (Or apes if your going to be that way.) I'm the 9th deadliest organism on the planet!

More complexity does not necessarily breed a better beast. Indeed, I am the apex of evolution and life in the universe. (Don't even talk to me about the Tardigrade. I don't want to hear it. Glorified bugs is all they are.)