An article in CBS News examined the ever-present concern about who should pick up the check on a date. It turns out that determining how the bill should be paid may be "less about independence and more about instinct." From the article:
Anthropologist Helen Fisher says it's natural for a man to want to pay the check and that something comparable happens all the time in the animal world.
"Chimpanzees will catch a little rabbit or hand over sugar cane. The bird catches a fish and hands it to the female," Fisher says. "The exchange of food for sex. It's called courtship feeding. You see it in insects. In fact, it's so common in insects that they call it the nuptial gift."
Online dating service Match.com also did a survey on the same subject and found that 71 percent of men think they should pick up the tab on a date and 58 percent of women agree. The article indicates that, although nowadays it is perfectly acceptable for the woman to pick up the check, the basic rules haven't changed much. Men still tend to have that instinct to pay as a symbol that they are looking for more than just friendship.