As far as I know it's a hormonal issue. Women, by necessity have a much greater fluctuation in their hormonal levels over time, and tears are the fastest way to flush the excess from the system. A tearful female would also garner attention from males.
A tearful man, on the other hand, would be less likely to bring home the bacon, as firstly he wouldn't be able to see it, and secondly, he'd have released all of that useful composure and aggression into his hankie. Result: his hungry,and probably tearful female is having dinner with joe next door.
It's just biology x evolution.