There is absolutely no reason to believe that 'higher intelligence' (conciousness) is the inevitable outcome of evolution. The most successful and longest existing groups on this planet are not intelligent.
We tend to assume that intelligence is the height of evolution because we still see ourselves as the pinnacle of evolution, instead of just another phase in it's long history.
I believe that the rise of higher intelligence on this planet is a fluke; if we ever find any extraterrestrial life it will not be intelligent.
Define successful. Also, this just shows that evolution can be inclusive, it's a tree, not a list: branches can coexist, often depend on it - as we are becomming increasingly aware of on this planet. It doesn't necessarily show that nature and evolution
doesn't favor intelligence (more time does mean higher intelligence). Aren't we all just complex adaptive machines, like automata, shaped by our externals (reactrive) and internals ("introactive"; reflective; introspective). Also, a rich ecosystem makes for
a much more interesting, complex and adaptive system (on several scales): much more to adapt to.