As social animals, we need to be around others. Virtually everything we do is social – trade, eating meals, watching sports in stadiums or movies in theaters, religious services, education, the internet, etc. Even war is a social activity. No human being on the planet is completely self-sufficient. Being social is more than utilitarian, however; it is also biologically and psychologically necessary. For example, one of the most severe forms of punishment in prisons is solitary confinement.
For infants and children, social deprivation is particularly harmful, both psychologically and physically. One reason for this is that we are primates with a prolonged period of prepubertal development, during which we are highly dependent on others – usually our mothers - for food, security, learning, and socialization. This was famously demonstrated in Harry Harlow’s experiments raising infant rhesus macaques (monkeys) in the 1950s. The infants, who were separated from their mothers, were provided with surrogate ‘mothers’ made either of soft terrycloth or a wire mother that also provided milk. Though the experiment seems cruel, an important lesson was derived from it: the infants preferred the terrycloth over the wire mothers, clinging to them and becoming attached to them. In short, security trumped food.
When the intense bond between mother and young is severed and not replaced with a suitable surrogate, the effects can be devastating. Writing about her observations in Gombe, Tanzania, Jane Goodall described what happened when a juvenile chimpanzee named Flint lost his mother, Flo:
Flo gave birth to at least five offspring: Faben, Figan, Fifi, Flint, and Flame. She was a wonderful, supportive, affectionate and playful mother to the first three. But she looked very old when the time came to wean young Flint and she had not yet fully succeeded in weaning him when she gave birth to Flame. When Flame died at the age of six months, Flo stopped even trying to push Flint to independence. Flint became abnormally dependent on his old mother and when Flo died in 1972, he was unable to cope without her. He stopped eating and interacting with others and showed signs of clinical depression. Soon thereafter, Flint’s immune system became too weak to keep him alive. He died at the age of eight and a half, within one month of losing his mother.”
At the risk of anthropomorphizing, from our point of view it seems that Flint died of grief – a broken heart. This is not out of the question. The biologist Marc Bekoff has written about the many examples of grief in other species, implying that it has deep evolutionary roots.
Of course, in humans the bond between infants and children with adults is not confined to biological mothers alone. Fathers, aunts, grandparents, older siblings, and adoptive parents also play crucial roles in raising young. In extreme cases, when children feel isolated, abused, shunned, or simply unloved, then the lack of strong bonds with others can become embedded in their biology through various pathways. For instance, severe psychological stress may increase stress hormones such as cortisol, inhibit growth hormone production, and lead to deficits in physical growth (Sapolsky, 1998). Even worse, there is recent evidence that emotional or physical abuse in childhood can accelerate aging by reducing the length of the telomeres on our chromosomes (Tyrka et al., 2010).
With respect to physical growth, the harmful effects of isolation on an infant or child can be ameliorated. In a study of premature infants in Miami, those who were actively touched and massaged gained weight significantly more rapidly than those who were not (Field et al., 1986). Importantly, this study has been replicated in Washington, D.C., as well as in India and Mexico (Gonzalez et al., 2009; Masaro et al., 2009; Mathai et al., 2001). Therefore, it seems that something as simple as physical touch is an inexpensive means of improving the growth of preterm infants. This makes sense and is compatible with an evolutionary perspective. The idea of keeping infants and children isolated goes against our nature as social primates or even as mammals requiring extensive parental care. We literally need love, and for children we can expect that the harmful effects of its absence will be experienced in predictable biological ways.
Related Post: Cosmically Connected Primates (Mar 8, 2012)
Field TM et al. (1986) Tactile/kinesthetic stimulation effects on preterm neonates Pediatrics. 77(5): 654-8.
Gonzalez AP et al. (2009) Weight gain in preterm infants following parent-administered Vimala massage: a randomized controlled trial. Am J Perinatol 26(4):247-52.
Massaro AN, et al. (2009) Massage with kinesthetic stimulation improves weight gain in preterm infants. J Perinatol 29(5):352-7.
Mathai S et al. (2001) Effects of tactile-kinesthetic stimulation in preterms: a controlled trial. Indian Pediatr. 38(10):1091-8.
Sapolsky (1998) Why Zebras Don’t Get Ulcers. New York: Freeman.
Tyrka et al. (2010) Childhood maltreatment and telomere shortening: preliminary support for an effect of early stress on cellular aging. Biological Psychiatry 67(6):531-4.