I love evolutionary psychology, you sound like my kind of person .
One concern that I have is that if you tell us the purpose of your study ahead of time, that might influence the voting and make the study bias. I am very fond of paleo and I want it to grow and spread so that more people can get healthy, and with this realization it seems that whatever you ask me about myself, I will lbe more ikely rate myself very highly so that people reading your study will perceive a connection between the paleo lifestyle and happiness and adopt the lifestyle to become happier, thus adding legitimacy and popularity to paleo that it didn't actually deserve. I think that paleo, health and happiness have a causal relationship, but my word isn't good enough. What if I really wasn't happy and paleo was actually affecting me negatively and yet I still rated myself highly because I was in denial and had an emotional attachment to paleo? That's not the case but I think that there are quite a few people in food movements or food religions (who will not be named) who are indeed in denial about the wisdom of their dietary choices. And so if voting is bias the numbers may not reflect reality.
So perhaps just say that you are taking a survey of people who practice the paleo/primal lifestyle but don't elucidate the true intention of the study. Anyway I will take your survey and answer truthfully.