Our babies, ourselves

Natural History, Oct, 1997 by Meredith F. Small, Robert A. LeVine

Nursing mothers slept alone with a new infant for fifteen months to insure its health. For the first three to six months, the Gusii mothers were especially vigilant for signs of ill health or slow growth, and they were quick to nurture unusually small or sick infants by feeding and holding them more often. Mothers whose newborns were deemed particularly at risk -- including twins and those born prematurely -- entered a ritual seclusion for several weeks, staying with their infants in a hut with a constant fire.

Mothers kept infants from crying in the early months by holding them constantly and being quick to comfort them. After three to six months -- if the baby was growing normally -- mothers began to entrust the baby to the care of other children (Usually six to twelve years old) in order to pursue tasks that helped support the family. Fathers did not take care of infants, for this was not a traditional male activity.

Because they were so worried about their children's survival, Gusii parents did not explicitly strive to foster cognitive, social, and emotional development. These needs were not neglected, however, because from birth Gusii babies entered an active and responsive interpersonal environment, first with their mothers and young caregivers, and later as part of a group of children. early hominids, known as australopithecines, still had rather small brains, one-third the present size. But starting about 1.5 million years ago, human brain size ballooned. Hominid babies now had to twist and bend to pass through the birth canal, and more important, birth had to be triggered before the skull grew too big.

As a result, the human infant is born neurologically unfinished and unable to coordinate muscle movement. Natural selection has compensated for this by favoring a close adult -- infant tie that lasts years and goes beyond meeting the needs of food and shelter. In a sense, the human baby is not isolated but is part of a physiologically and emotionally entwined dyad of infant and caregiver. The adult might be male or female, a birth or adoptive parent, as long as at least one person is attuned to the infant's needs.

The signs of this interrelationship are many. Through conditioning, a mother's breast milk often begins to flow at the sound of her own infant's cries, even before the nipple is stimulated. New mothers also easily recognize the cries (and smells) of their infants over those of other babies. For their part, newborns recognize their own mother's voice and prefer it over others. One experiment showed that a baby's heart rate quickly synchronizes with Mom's or Dad's, but not with that of a friendly stranger. Babies are also predisposed to be socially engaged with caregivers. From birth, infants move their bodies in synchrony with adult speech; they are hard-wired to absorb the cadence of speech and the general nature of language. Babies quickly recognize the arrangement of a human face -- two eyes, a nose, and a mouth in the right place -- over other more Picasso-like rearrangements. And mothers and infants will position themselves face-to-face when they he down to sleep.