March 14, 2019 - Psychology Today
In her excellent review, naturalist, author, and scriptwriter, Sy Montgomery writes, "In this book, de Waal sets the record straight. Emotions are neither invisible nor impossible to study; they can be measured. Levels of chemicals associated with emotional experiences, from the 'cuddle hormone' oxytocin to the stress hormone cortisol, can easily be determined. The hormones are virtually identical across taxa, from humans to birds to invertebrates."