"The answer is memes. And the short reason why is: memes evolve much, much faster than genes, so once they existed, they got to do everything mind-related, and biological evolution no longer got to do anything. This also explains why genes aren't a suitable answer :)"
Yes, memes exist, and they do quite a lot, but it's not like as soon as memes showed up, everything else went out the door! Even if we assume that memes had some ability to thwart further biological evolution, that wouldn't reverse all of the built-in stuff that existed at the point memes came on the scene. Everything that memes do is layered on top of the huge amount of pre-programming that we're born with; memes exist solely on the highest thin layer of a big multi-layered system. Don't forget that we're actually primates with primate brains, and mammals with mammal brains. Millions of years of mammalian brain evolution weren't discarded just because we invented a vehicle for meme transmission (language). That high-level idea transmission mechanism resides on top of a regular ol' primate brain, with all of its complex builtin emotions for survival, reproduction, social interaction, etc.
Anyway, I'm not an expert on this stuff, so I can't put together a really convincing argument citing specific experimental facts and whatever. I'm starting to repeat myself ... shows how little I know about this stuff. You should read some of the stuff on EvPsych to draw your own conclusions about the validity of the field.
Check out this blog post on Overcoming Bias: http://www.overcomingbias.com/2007/11/evolutionary-ps.html
