Why are men so cheap? Blame testosterone:
"Our broad conclusion is that testosterone causes men essentially to be stingy," says Karen Redwine, a neuro-economist at Whittier College in California [...] To make this case, Redwine and her colleague Paul Zak, at the Claremont Graduate University in California, gave a testosterone-containing gel to 25 male university students, and then tested their generosity.
The students then played a simple economic game with another participant via a computer. One volunteer is tasked with splitting $10 with another volunteer in any way he likes. The other volunteer either accepts the offer or rejects it as unfair, in which case no one gets any money. Each volunteer played this game in both roles, on and off the testosterone gel.
Overall, the testosterone cream caused a 27 per cent reduction in the generosity of the offers, from averages of $2.15 to $1.57, Redwine and Zak found.
The article also described how oxytocin, the so-called cuddle chemical, can actually boost generosity: Link