certain monkeys during a certain slice of time, demographic profiles suggest they are not unusual for wild animal populations more generally.
Experiencing the death of a groupmate, then, or even of one’s offspring or other close kin or social partner, is far from rare for group-living wild animals. If we think about mourning and grief in terms of evolutionary theory, a negative hypothesis (the “null hypothesis,” in scientific terms) may come to mind: Wild animals faced with the challenges of survival and reproduction should not expend time or energy on the expression of grief when a group member dies. A weaker version of this same hypothesis would be that wild animals should expend time or energy on grieving only when the resources required for survival are available in sufficient abundance.
If a death provokes no particular emotional response, might this absence of grief be explained as an energy-saving strategy that is under the control of natural selection? If so, might some of the survivors feel emotion but simply ignore it? Or are no emotions felt? By observation alone, without the invasive measures of stress physiology, we cannot distinguish between these alternatives. (We’ll consider what those invasive measures do teach us in a moment.)
If any toque macaque is likely to mourn the death of the youngster plucked from the lake by the monitor lizard, it would be his mother. The mother-infant relationship in macaques, as in almost all primates, is exquisitely close. Research shows that in rhesus macaques, a close relative of the toques, mothers and infants share what’s called reciprocal face-to-face communication. This suite of behaviors between moms and babies involves smacking of the lips, mouth-mouth contacts, and, most significant of all, sustained mutual gaze.
Think of how important mutual gaze is in our own species, as bonds develop between babies and their caretakers. A memory so vivid that I’ve carried it for nineteen years comes from my daughter Sarah’s infancy. It was a Saturday, exactly four weeks since her birth. I was carrying Sarah in my arms across the street in front of our house, on my way to pay a welcome call on new neighbors. When I glanced down at her, bundled up against the chill November air, she locked eyes with me and let loose with a huge smile. It was what developmental psychologists call a social smile, the kind of aware, intentional smile that is set apart from the reflexive mouth movements of a newborn. To me, a tired but otherwise besotted new mother, the mutual gaze and first social smile meant one thing: my baby was loving me back.
The contours of the emotional relationship between monkey mothers and babies aren’t well studied. It’s reasonable to expect, though, that gaze and facial expressions shared across the generations both enhance infant survival and cause feelings of comfort or pleasure to flow within the pair. Newborn monkey babies cling to their mothers’ bellies; in the beginning, the mother is the infant monkey’s universe, the source of all warmth, nutrition, and safety. For the mother, infant care is all-consuming. She starts out carrying the infant on her body around the clock (except in a few monkey species where dads and siblings help out). Moms may bounce their babies, play with them, smack their lips in affection toward them, and try to catch their babies’ eye to facilitate that mutual gaze.
That many monkey mothers lose their infants early on is something we know from the mortality profiles. When this happens, some mothers simply put down the body, or leave it where it fell, and carry on with their lives. No visible grief seems to accompany these acts of abandonment. Other mothers, though, continue to carry their infants’ dead bodies. Could this carrying be an expression of maternal grief ?
Maternal carrying of infant corpses was monitored by primatologist Yukimaru Sugiyama and colleagues for more than two decades in one population of
Experiencing the death of a groupmate, then, or even of one’s offspring or other close kin or social partner, is far from rare for group-living wild animals. If we think about mourning and grief in terms of evolutionary theory, a negative hypothesis (the “null hypothesis,” in scientific terms) may come to mind: Wild animals faced with the challenges of survival and reproduction should not expend time or energy on the expression of grief when a group member dies. A weaker version of this same hypothesis would be that wild animals should expend time or energy on grieving only when the resources required for survival are available in sufficient abundance.
If a death provokes no particular emotional response, might this absence of grief be explained as an energy-saving strategy that is under the control of natural selection? If so, might some of the survivors feel emotion but simply ignore it? Or are no emotions felt? By observation alone, without the invasive measures of stress physiology, we cannot distinguish between these alternatives. (We’ll consider what those invasive measures do teach us in a moment.)
If any toque macaque is likely to mourn the death of the youngster plucked from the lake by the monitor lizard, it would be his mother. The mother-infant relationship in macaques, as in almost all primates, is exquisitely close. Research shows that in rhesus macaques, a close relative of the toques, mothers and infants share what’s called reciprocal face-to-face communication. This suite of behaviors between moms and babies involves smacking of the lips, mouth-mouth contacts, and, most significant of all, sustained mutual gaze.
Think of how important mutual gaze is in our own species, as bonds develop between babies and their caretakers. A memory so vivid that I’ve carried it for nineteen years comes from my daughter Sarah’s infancy. It was a Saturday, exactly four weeks since her birth. I was carrying Sarah in my arms across the street in front of our house, on my way to pay a welcome call on new neighbors. When I glanced down at her, bundled up against the chill November air, she locked eyes with me and let loose with a huge smile. It was what developmental psychologists call a social smile, the kind of aware, intentional smile that is set apart from the reflexive mouth movements of a newborn. To me, a tired but otherwise besotted new mother, the mutual gaze and first social smile meant one thing: my baby was loving me back.
The contours of the emotional relationship between monkey mothers and babies aren’t well studied. It’s reasonable to expect, though, that gaze and facial expressions shared across the generations both enhance infant survival and cause feelings of comfort or pleasure to flow within the pair. Newborn monkey babies cling to their mothers’ bellies; in the beginning, the mother is the infant monkey’s universe, the source of all warmth, nutrition, and safety. For the mother, infant care is all-consuming. She starts out carrying the infant on her body around the clock (except in a few monkey species where dads and siblings help out). Moms may bounce their babies, play with them, smack their lips in affection toward them, and try to catch their babies’ eye to facilitate that mutual gaze.
That many monkey mothers lose their infants early on is something we know from the mortality profiles. When this happens, some mothers simply put down the body, or leave it where it fell, and carry on with their lives. No visible grief seems to accompany these acts of abandonment. Other mothers, though, continue to carry their infants’ dead bodies. Could this carrying be an expression of maternal grief ?
Maternal carrying of infant corpses was monitored by primatologist Yukimaru Sugiyama and colleagues for more than two decades in one population of
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