Anthropologist Helen Fisher has long been trying to answer the question: why do you fall in love with one person rather than another? Her research says we've evolved four basic styles of thinking and behaving linked with the dopamine, serotonin, testosterone, and estrogen systems. Fisher used that research to create a questionnaire that's been taken by 15 million people in 40 countries, shedding light on how we choose our mates.

She's also one of the experts behind the Singles in America survey from Match.com, the most recent of which shows that people are using AI in online dating, and are increasingly trying alternatives to monogamy.

• Plus, Axios' Carly Mallenbaum on legal protections for polyamorous relationships.

Guests: Helen Fisher, anthropologist and chief science advisor to Match.com; Axios lifestyle reporter Carly Mallenbaum.

Credits: 1 big thing is produced by Niala Boodhoo, Alexandra Botti, and Jay Cowit. Music is composed by Alex Sugiura and Jay Cowit. You can reach us at [email protected]. You can send questions, comments and story ideas as a text or voice memo to Niala at 202-918-4893.