Cooperative Eyes
Contextual Quote
"The hallmark of our egalitarian nature is the design of our ‘cooperative eyes’, they invite anyone we interact with to see easily what we are looking at. By contrast, great apes have round, dark eyes. They disguise their thoughts from others. This suits a primate world of Machiavellian competition."
- Camilla Power [1]
Discussion
Camilla Power:
"Let’s begin with the biology. Perhaps the hallmark of our egalitarian nature is seen in the design of our eyes. We are the only one of well over 200 primate species to have evolved eyes with an elongated shape and a bright white sclera background to a dark iris. Known as ‘cooperative eyes’, they invite anyone we interact with to see easily what we are looking at. By contrast, all great apes have round, dark eyes, making it very difficult to tell from eye direction what they are looking at. Like mafia dons wearing sunglasses, they watch other animal’s moves intently, but disguise from others what they are thinking about. This suits a primate world of Machiavellian competition.
Our eyes are adapted for mutual mindreading, also known as intersubjectivity; our closest relatives block this off. To look into each other’s eyes, asking ‘can you see what I see?’ and ‘are you thinking what I am thinking?’ is completely natural to us, beginning from an early age. Staring into the eyes of other primate species is taken as a threat. This tells us immediately that we evolved along a different path from our closest primate relatives.
In Mothers and Others, Hrdy gives the most convincing account of how, why and when this happened. She presents a straightforward argument. We do babysitting in all human societies, mothers being happy to hand over their offspring for others to look after temporarily. African hunter-gatherers are the champions of this collective form of childcare, indicating that it was routine in our heritage. In stark contrast, great ape mothers – chimpanzees, bonobos, gorillas and orang utans – simply will not let their babies go. Because of the risks of harm to their infants, they are hyperpossessive and protective, not daring to take the chance.
This particularly applies to great apes. Monkeys behave differently, being prepared to leave a baby with a trusted relative. The key factor involved is exactly how closely related individuals are. Old World monkey mothers usually live with female relatives; great ape mothers don’t. This means ape mothers have no one nearby whom they can trust sufficiently. This is telling us something significant about the social conditions in which we evolved. Our foremothers must have been living close to trusted female relatives, the most reliable in the first place being a young mother’s own mother. This ‘grandmother hypothesis’ has been used to explain our extraordinarily long postreproductive lifespans – the evolution of menopause.
Hrdy explores how multi-parental care shaped the evolution of our species’ unique psychological nature. While cooperative childcare may start with the mother-daughter relationship, bonding with grandchildren would quickly lead to the involvement of aunts, sisters, older daughters and other trusted relatives. From the moment when mothers allow others to hold their babies, says Hrdy, selection pressures for new kinds of mind-reading are established. These give rise to an array of novel responses – mutual gazing, babbling, kissfeeding and so forth – to enable this variegated triad of mum, baby and new helper to consolidate bonds while monitoring one another’s intentions. Within a few short hours after birth, a baby in an African hunter-gatherer camp will have been introduced to and held by numerous relatives and friends, of both sexes."