Anna Machin is an evolutionary anthropologist, writer, and broadcaster. She earned her PhD in 2006 and has spent the time since exploring the science behind our closest relationships, most recently at the University of Oxford in evolutionary psychologist Robin Dunbar’s lab. She is a passionate science communicator, has written for New Scientist, The New York Times, The Guardian, and Aeon, and is a regular contributor to the BBC, ABC, and NPR.