Penny Lane gave up months of wages and weeks of her life to have her kidney cut out and given to someone she never knew, and who may never thank her. She is one of about 200 people in the US a year who give up a kidney altruistically. What motivates someone to do that? Evolutionary psychologist Michael McCullough believes that not only is there true altruism amongst the human species, but that it is a unique trait, an emerging and spreading trait, and it is selected for by evolution, even out-competing the more familiar traits of selfishness that drive evolution in other species. And the trait is responsible for moral progress in the world. Barry is skeptical, and calls friend of the show Kieran Setiya to talk him out of his skepticism, only to discover that, in many ways, humans are even worse than he thought. We may have evolved to demand altruism from others, but not be altruistic ourselves. This episode brought you by Scribd and Inkl. Get an enormous library of books, magazines, podcasts, and audiobooks. Try Scribd for 60 days free. try.scribd.com/hiphi Unlock reliable news sources from their paywalled sites, The Economist, The Atlantic, Bloomberg, and 100 more, a $12,000 annual value for just $75 the first year. Go to inkl.com/philosophy to get this deal. God and the Space-time Manifold is a summer seminar at Rutgers Center for the Philosophy of Religion June 13-24th, 2022. Twelve philosophers will lead discussions about God and the philosophy of time. They are looking for applicants. All professional philosophers and graduate students qualify. Sign up for Slate Plus, to receive ad-free version of this podcast and unlimited access to Slate. Learn more about your ad choices. Visit megaphone.fm/adchoices