That saying about nice guys may have to be changed.
A study, published in Evolutionary Psychology January 2016, found that 202 women, when presented with different men combined with knowledge of whether they had done a good deed or not, chose the altruistic man for a long-term relationship regardless of how physically attractive they were.
Granted, they tended to choose attractive, selfish men for a one night stand most times, but long term relationships were predominately for good Samaritans.
Meanwhile, another study published January 2015, showed that those who reported doing good deeds were more likely to say they were in a relationship the subsequent year, than those who did not.
Many previous studies have also shown that altruism is important to mate selection, while other traits such as humour and intelligence have been found to play a role too.
However, generosity was found to matter above all other traits by a 2013 psychological study especially in the case of long-term relationships.
Many of these studies have small sample sizes, and it's worth considering whether people behave the same in a laboratory with anonymous test subjects compared to your average pub, bar or dinner party.
But in short, the science says if you're looking for long-term love you probably need to think a bit about what you're giving.