— In tough times, a parents best bet for passing on their genes could be to reduce the care they give to their children, according to a provocative theory. Now new research seems to suggest this actually happens.
According to life history theory, humans have two major decisions: whether to reproduce now or later, and how much care to invest in each child.
In extremely hazardous situations, where good parenting is unlikely to improve their offsprings chances of survival, parents would do better to shift the focus of their reproductive efforts from childcare to mating, the theory says. Switching their energy resources to either mating effort to produce additional offspring, or even self-preservation (to enhance their fitness) would increase the chance that their genes will survive.
Robert Quinlan at Washington State University in the US analysed data from a range of developing societies, and found that as the frequency of war or famine increased, maternal care did indeed decrease.
As disease levels increased, levels of parental care rose initially, then hit a threshold level and decreased presumably when extra care was unlikely to improve a childs chance of survival.
It is interesting work and will lead to a lot of discussion, if the data used is indeed accurate, says Adrian Sleigh, who studies international health and epidemiology at the Australian National University in Canberra.
If a family is confronting a very hostile environment, they probably have very limited time for parenting because they are out trying to protect the family, or to get food and water. Or they are sick themselves," he argues: They might want to invest more time in parenting but they just can't.
Quinlan used data from the Standard Cross-Cultural Sample, a reference set of data from 186 mostly pre-industrial societies across the world, archived by the journal World Cultures.
He rated three sources of environmental stress: total pathogen stress (levels of malaria, leishmaniasis and leprosy, for example), overall frequency of warfare and severity of famine.
Quinlan also rated maternal care using information on the physical closeness of the mother and child during sleep, how she responded to crying, and levels of body contact in early infancy. And he considered paternal involvement, rated on a scale from distant to close in both infancy and early childhood.
The data on responses to varying levels of warfare, famine and disease fit with life history theory, he says, which has implications for how we can mitigate the social impacts of these stressors.
If we wish to promote responsive parenting, then it's important not to promote the perception that we live in an environment of pervasive and unpredictable hazards, Quinlan warns.
I wonder what kind of parents children will become when they've grown up in a society that sees deadly risks everywhere, such as the threat of terrorist attacks. That kind of risk perception could lead to mating effort reproductive strategies that could reverberate behaviourally for generations, he told New Scientist.
"Quinlan seems to be implying that in certain situations, parents stop effectively throwing good money after bad," Sleigh says, "but Im not convinced theres any rational rationing of parental effort going on here."
Journal reference: Proceedings of the Royal Society B (DOI: 10.1098/rspb.2006.3690).
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