Natalie Angier in her article, "In a Helpless Baby, the Roots of Our Social Glue," points out that:
In the view of the primatologist Sarah Blaffer Hrdy, the extraordinary social skills of an infant are at the heart of what makes us human. Through its ability to solicit and secure the attentive care not just of its mother but of many others in its sensory purview, a baby promotes many of the behaviors and emotions that we prize in ourselves and that often distinguish us from other animals, including a willingness to share, to cooperate with strangers, to relax one’s guard, uncurl one’s lip and widen one’s pronoun circle beyond the stifling confines of me, myself and mine. As Dr. Hrdy argues in her latest book, “Mothers and Others: The Evolutionary Origins of Mutual Understanding,” which will be published by Harvard University Press in April, human babies are so outrageously dependent on their elders for such a long time that humanity would never have made it without a break from the great ape model of child-rearing. Chimpanzee and gorilla mothers are capable of rearing their offspring pretty much through their own powers, but human mothers are not.
Human beings evolved as cooperative breeders, says Dr. Hrdy, a reproductive strategy in which mothers are assisted by as-if mothers, or “allomothers,” individuals of either sex who help care for and feed the young. Most biologists would concur that humans have evolved the need for shared child care, but Dr. Hrdy takes it a step further, arguing that our status as cooperative breeders, rather than our exceptionally complex brains, helps explain many aspects of our temperament. Our relative pacifism, for example, or the expectation that we can fly from New York to Los Angeles without fear of personal dismemberment. Chimpanzees are pretty smart, but were you to board an airplane filled with chimpanzees, you “would be lucky to disembark with all 10 fingers and toes still attached,” Dr. Hrdy writes.
Our capacity to cooperate in groups, to empathize with others and to wonder what others are thinking and feeling — all these traits, Dr. Hrdy argues, probably arose in response to the selective pressures of being in a cooperatively breeding social group, and the need to trust and rely on others and be deemed trustworthy and reliable in turn. Babies became adorable and keen to make connections with every passing adult gaze. Mothers became willing to play pass the baby. Dr. Hrdy points out that mother chimpanzees and gorillas jealously hold on to their infants for the first six months or more of life. Other females may express real interest in the newborn, but the mother does not let go: you never know when one of those females will turn infanticidal, or be unwilling or unable to defend the young ape against an infanticidal male.
By contrast, human mothers in virtually every culture studied allow others to hold their babies from birth onward, to a greater or lesser extent depending on tradition. Among the !Kung foragers of the Kalahari, babies are held by a father, grandmother, older sibling or some other allomother maybe 25 percent of the time. Among the Efe foragers of Central Africa, babies spend 60 percent of their daylight hours being toted around by somebody other than their mother. In 87 percent of foraging societies, mothers sometimes suckle each other’s children, another remarkable display of social trust.
You can read the whole article at: http://www.nytimes.com/2009/03/03/science/03angi.html?th&emc=th
I appreciate that our dependence on each other wires us for smiling, love, trust and peace.