My closest brush with motherhood was an intense 24 hours fostering an orphaned baby owl monkey in the Peruvian Amazon in 2009. According to Charles Darwin, my maternal drive should have transformed me into an intuitively wise and selfless nurse. But the truth was I felt quite traumatized—fretful, exhausted, and for the sake of my defiled and defecated hair alone (the baby was happiest when clinging to my head), uninclined to repeat the ordeal ever again. I was 39 at the time and wrestling with whether I should be having children myself. My night with the owl monkey reinforced my suspicion that I was not cut out for motherhood.

Females have long been equated with motherhood, as if no other role existed. But my research about motherhood in the animal kingdom taught me that materna…