Generosity feels like a good idea - most of us enjoy being generous from time to time and having people be generous to us. But what drives our altruistic tendencies? From local volunteering to big philanthropic donations, from small acts of kindness to major sacrifices, what does this sort of behaviour say about us as human beings? Do we really give without expecting something in return, or is there always some element of self- interest? Joining Bridget Kendall to explore how and why we are generous are evolutionary anthropologist David Sloan Wilson, philosopher Judith Lichtenberg and experimental psychologist Patricia Lockwood. Photo: Offering Aid after forest fire. Credit Cole Burston AFP Getty Images