Science seems to be able to find an answer to most anything these days. This article isn't particularly exciting, but I found it very informative and interesting.
It's about the studies that have and are being done showing the distinct differences in the male and female brain. It also goes into detail explaining why we (men and women) react differently to different situations. The ramifications for relationships are fairly obvious to see... so if you're in a relationship, or are planning on being in one, I'd suggest giving it a read.