Despite some of our most obvious short-comings, humans are really smart. Just look at all of the things that we've accomplished as a species -- creating advanced technology, building masterpieces, arts and music -- all things that other species aren't developed enough to achieve. But scientists wanted to know if intelligence had any affect on how we find mates.
Evolutionary psychologists, a.k.a. very smart people, investigated whether intelligence or humor was a more heavily weighted factor when finding someone attractive.
What did they find? Its actually the perception of being funny that's more relevant for being an attractive potential partner. An important note though, being perceived as smart has an impact too, but you don't actually have to be smart.
This experiment was actually really involved and pretty impressive. Read about it in depth here.