In The Expressions of the Emotions in Man and Animals, published a decade after On The Origin of Species, Charles Darwin explained how human and animal faces reflect emotional states. Our nervous systems scribe our inward feelings onto our faces, even when our intellect would rather conceal what is within. Sensitivity to the nuances of facial expression is a core part of our being, Darwin claimed.
Darwin focused on the nervous and muscular mechanisms that translated emotions into facial expressions, implicitly assuming that observers of faces would interpret them correctly. In the early and mid-twentieth century, Konrad Lorenz, one of the first proponents of the evolutionary study of animal behavior, made explicit what Darwin had assumed. Lorenz analyzed faces as forms of communication... Lorenz also extended Darwin's analysis by considering why humans are attracted to some animal faces and not to others.
He concluded that our affinity for the faces of human babies could mislead us when we viewed animals. We see baby-faced animals as "lovable," even if the animals' true characters are decidedly not cuddly. Lorenz believed that large eyes, rounded features, proportionally large heads, and short limbs all release in us an instinct to embrace and to pet.
