Millions of years ago, we evolved three basic drives: the sex drive, romantic love and attachment to a long-term partner. These circuits are deeply embedded in the human brain. They’re going to survive as long as our species survives.

Fisher frames human pair-bonding as an evolved, modular system rather than a single, undifferentiated “love instinct.” By separating sex drive, romantic love, and long-term attachment, she argues that different neural circuits can be activated independently—helping explain phenomena such as desire without commitment, intense infatuation without sexual interest, or enduring bonds after passion fades. The claim that these circuits are “deeply embedded” and likely to persist positions love and attachment as durable features of human nature, not merely cultural inventions. It also implies that social change may reshape how relationships are organized, but not eliminate the underlying biological motivations that propel them.