00:00 Are we really supposed to be monogamous for life?

04:49 Scientists study the brains of people in love to understand what happens in the brain when someone is intensely in love.

09:18 The brains of people in love show activity in the ventral tegmental area, which produces dopamine and is associated with wanting, craving, obsession, focus, and motivation, suggesting that romantic love is generated in brain regions linked to these feelings.

13:25 Monogamous voles have more oxytocin receptors in their brains compared to non-monogamous voles, suggesting that oxytocin plays a role in bonding and monogamy.

17:13 Oxytocin receptors play a role in driving voles to stay together for life, and while humans also have these receptors, our complex brains make it unclear how much they motivate us to stay in long-term relationships.

21:35 Our earliest ancestors were likely polygynists, meaning one male to several females, which challenges the idea that humans evolved to be monogamous for life.

27:13 The question of whether humans evolved to be monogamous or polygynous is still debated among academics, with some pointing to the size difference between men and women as evidence for polygyny, while others argue that size is not a reliable indicator and point to chemicals in our brains and rates of male violence as evidence for monogamy.

31:07 Even though some species, including humans, form bonds with their partners after mating, it doesn't mean they won't cheat, as evidenced by genetic tests on voles and observations of cheating in the animal kingdom, including birds; infidelity is relatively widespread among couples.

35:21 Infidelity is found throughout the animal kingdom and there are always individuals that break the mold, such as the voles that didn't bond with their male partners and instead coupled up with each other to raise their kids.