The other night, I was talking with a group of seven graduate students about sexual fantasies. No, not their sexual fantasies. We were talking about some data about sexual fantasies that I and two of the present students had gathered that showed a very strong and reliable sex difference that, as far as we know, no else had ever found.I won’t tell you what the result was – we’re still working on the project, and it’s not ready for prime time – but I will tell you why I’m relating the story. One of the comments made by a graduate student caught my attention. As we were explaining the results of the studies we had run to that point, the student – I will call him George – remarked that the pattern that we had found was quite interesting. He indicated that the finding was so compelling, in fact, that he didn’t see why we were so focused on finding anexplanation for it. The results, said George, stood on their own. Why, in short, ask why?This struck me because my understanding of the reason that people choose to go to graduate school – to pursue science– is because of an interest in explanations. I myself grew up reading science fiction, and those explorations led me to science because science was a lot like trying to solve a puzzle – Find the Right Explanation – for which there wasn’t an answer key. The point, I suppose, is that I thought – and, more or less, continue to think – that the whole point of science is coming up with – and, it goes without saying, testing – explanations. Why, I wondered, ask “why ask why?”I don’t by any means intend this to be a slight. People are entitled to be curious – or not – about anything they wish. Certainly, others have articulated the idea that to explain a thing is to take something vital from it – explanations of jokes have this sort of feel – but I, and I think many others, take the reverse view, that explanations only add to our joy in what we observe. (Aside: Is this why museums provide explanations near their displays? And why so many people consume the displays but eschew the plaques?)This anecdote is just to say what I take to be the added value of evolutionary psychology: it points to explanations. Or, to go further, a key part of the value of evolutionary psychology is that it points to deep explanations.In 2011,, published a little piece by one of my favorite psychologists, Tim Wilson. Just as TVOL is engaging with the question of just what evolutionary psychology is, Edge, via Wilson, was engaging with the question of just what social psychology is (anyway).In any case, Wilson’s piece stimulated a discussion on Edge with a number of other prominent scholars, including Steve Pinker, a well-known exponent of evolutionary approaches to psychology. The dialog was illuminating. Briefly, responding to Wilson’s (skeptical) discussion of what evolutionary psychology as a discipline adds, Pinker claimed that evolutionary psychology adds quite a lot indeed, pointing to a paper that listed novel contributions of the discipline. Wilson replied this way:“I went back and checked … Many of them fail the novelty test in that they were well-known phenomena before evolutionary psychology existed, such as, "Sex difference in opposite-sex friendships." Does Steve [Pinker] mean to imply that it wasn’t until evolutionary psychology took hold in the in 1970s and 1980s that we discovered that there was such a phenomenon? For many of the items it is not the phenomenon that is novel but the explanation of it.”This notion that it is somehow damning for a field – or, perhaps, a scientist – to add “only” a novel explanation is, to my mind, singular. Before Newton, pretty much everyone had noticed that things fall. “All” Newton added was an explanation. To take a more pertinent example, before 1859, it was exceedingly well known that plants and animals came in many different types, each with their own traits. “All” Darwin did was provide an explanation for this well-documented phenomenon.Wilson continued, adding that “Evolutionary psychologists did not discover these phenomena,” and wonders “how much we need evolutionary theory to explain these phenomena.” In the end, he questions why a field such as social psychology “needs to find explanations outside of its own principles and constructs.”This short essay isn’t the place to get into the details of the explanatory power of the evolutionary approach to (human) behavior. In some sense, I’m happy to say that it’s possible to catalog, count, and codify human behavior, marvel in its wonder, and complacently settle for measuring, rather than understanding.But I, for one, am not inclined toward such complacency. Neither do I find satisfying explanations that are shallow, if they are explanations at all, such as frequently-repeated one-word proposals such as “learning,” “culture,” or “plasticity.”What I want as deep an explanation for our new data on sexual fantasies as possible and, ever since Darwin, we’ve known where to start to look for one.ReferenceBuss, D.M., & Reeve, H.K. (2003). Evolutionary psychology and developmental dynamics. Psychological Bulletin, 129, 848-853.