Neurologists and philosophers alike may argue that altruism doesn't exist because no act is ever completely unselfish. Learn why -- and why humans may have evolved this way -- in today's episode of BrainStuff, based on this article: https://science.howstuffworks.com/life/evolution/unselfish-act.htm

How Can Rhubarb Grow in the Dark?
10:28

How Does the Blue-Footed Booby Work?
08:41

Who Was Helen of Troy?
07:27