Unless an atheist believes the pinnacle of evolution is, say, the dolphin, then I'd argue that he believes himself (and those as much like him as possible) to be the height of evolution indeed. And if voting for an atheist includes voting for someone who is secretly an atheist, then the question is useless.
To be precise, not believing in that one specific belief makes one an agnostic; it's a belief that no convincing evidence exists for a Creator. Believing in the opposite of that one specific belief makes one an atheist; it's a belief that convincing evidence exists that there is no Creator.
Where do you get your information from? Please allow me to clarify a few points:
There is no such thing as an evolutionary "ladder" except in the minds of Creationists as a ready-to-hand straw man. Darwin's original visualisation of a tree (along with associated "I think") actually does a very good job of summarising what we know regarding this. And if there were a ladder, we would not be at the top.
Agnosticism is a belief that the question regarding the existence of God(s) is inherently unknowable.
Atheism is a belief that there is no god.
The two are not mutually exclusive.
I have no problem with agnostics, but the overweening hubris required to be an atheist is rather hard to overlook. To believe there is no G-d, no Creator, is literally claiming to understand all of Creation well enough to determine it arose through natural means. That's a breathtaking leap of faith and arrogance.
I singled out this quotation because it literally rendered me speechless.
Just like how you don't have to understand every single one of God's motivations or actions to be a Christian, you don't need a complete understanding of the universe to be an atheist.