What she and her co-author found was that men's response to donating is effected by two factors: how attractive a female fundraiser is and how much other men have donated. Males actually appear to compete with each other when donating to a 'high quality' (my words) potential mate. Interestingly, and potentially useful for the fundraising sector, females don't compete when donating to attractive male fundraisers. So there seems to be an aspect of sexual competition between males...
All really useful and cool stuff. Plus it's come from the use of a large database, and more studies are likely to come out as big data becomes more available for biologists. I just hope that people don't take this literally and that facebook now doesn't start bombarding me with charity adverts featuring scantily clad women telling me that my male friends have donated £100! This is great research into how humans cooperate and what drives our behaviour when performing seemingly altruistic behaviours.
Raihani & Smith (2015) Competitive helping in online giving. Current Biology,
Unconditional generosity in humans is a puzzle. One possibility is that individuals benefit from being seen as generous if there is competition for access to partners and if generosity is a costly—and therefore reliable—signal of partner quality [ 1–3 ]. The “competitive helping” hypothesis predicts that people will compete to be the most generous, particularly in the presence of attractive potential partners [ 1 ]. However, this key prediction has not been directly tested. Using data from online fundraising pages, we demonstrate competitive helping in the real world. Donations to fundraising pages are public and made sequentially. Donors can therefore respond to the behavior of previous donors, creating a potential generosity tournament. Our test of the competitive helping hypothesis focuses on the response to large, visible donations. We show that male donors show significantly stronger responses (by donating more) when they are donating to an attractive female fundraiser and responding to a large donation made by another male donor. The responses for this condition are around four times greater than when males give to less-attractive female (or male) fundraisers or when they respond to a large donation made by a female donor. Unlike males, females do not compete in donations when giving to attractive male fundraisers. These data suggest that males use competitive helping displays in the presence of attractive females and suggest a role for sexual selection in explaining unconditional generosity.