In particular, Pearson’s team looked at facial expressions depicting emotional states. In an elegantly designed experiment, they showed human mothers-to-be images of human faces, and asked them to rate the emotions expressed on those faces. As pregnancy progresses, mothers become more efficient at recognizing the emotions on the faces of others. Intriguingly, the greatest recognition increase pertains to faces exhibiting dangerous conditions – fear (perhaps of a visible threat), disgust (contamination threat), and anger (direct physical threat).
Normally calm women may be disturbed to find themselves suddenly beset by new fears and catastrophic visions while pregnant. Indeed, the authors compare pregnant women’s threat-sensitivity levels to those found in people with anxiety disorders. But they suggest that the ability to recognize these threat conditions is an evolutionary adaptation to help females protect their offspring-to-be from harm.
The evolutionary tale rings true when considering post-partum primates. Anyone who has watched a human mother and her child knows that they gaze at one another in a way that suggests they are studying faces and expressions, a phenomenon examined by numerous researchers. Taking matters further, researchers have found that chimpanzee and rhesus macaque infants and mothers spend a significant amount time gazing at one another, looking into and recognizing each other’s faces. In photos, the primate mothers gazing at their infants bear a remarkable resemblance to “Madonna and Child” paintings. The researchers suggest that this emotional recognition helps with bonding and learning.
If studying the faces of offspring is mutually beneficial in the post-partum period, perhaps the increase in facial recognition during pregnancy is playing the dual role of protecting offspring from threats and preparing mothers for their unique bonding experience. That hypothesis would seem to be supported by the work of Ruth Feldman of Bar-Ilan University and colleagues, who in 2007 showed a correlation between the levels of oxytocin (the “love” and “bonding” hormone, which is also associated with the formation of breast milk) during pregnancy and the amount of time that mothers and infants spent gazing at one another. A race car peeling rubber indeed! This study, combined with Pearson’s work, makes a strong argument that not only are hormones helping pregnant females defend their infants-to-be from the dangers in the world around them, but also preparing females to be loving mothers after giving birth.
The hormones do have a downside. Some new mothers suffer from depression and in rare cases, even psychosis. Research at Tufts University and elsewhere suggests some potential animal models and endocrinological mechanisms for postpartum mental distress, broadly defined. It suggests that hormones are to blame: an acute pull-back, addict-like, from the rich concentrations of steroids that characterize pregnancy may play a role in the severity of postpartum reactions.
So what about fathers? Are the dads among us doomed to stand idly by, clueless and bereft of meaningful emotional contact, while mothers reap the endocrinological, neurological, and emotional benefits of motherhood? Take heart, XY-ers! A 2008 study similar to Pearson's found that men administered oxytocin were better able to identify happy emotions in the faces of others. So, whereas we males may not receive a boost in our threat-response abilities, hormones in men may at least allow us not to loathe the occasional requisite diaper-changing.