Does Your Baby Actually Want You to be Tired?


So in a small departure, this week’s post takes a look at a theory from evolutionary biology not anthropology. This is not my specialism so apologies for any over-simplification but I thought it was so interesting it was worth writing about.

Mother and baby: a relationship in harmony or in conflict?

Most people in the West have pretty incoherent and conflicting beliefs around the relationship between mothers and their babies. On the one hand having a baby is seen as the most natural thing in the world, mothers and babies are seen as working in harmony, each biologically programmed to work together for the best possible outcome. On the other hand, birth is incredibly dangerous, babies are exhausting and are occasionally described as ‘manipulative’ for wanting more milk or crying a lot. Harmony on the one side and conflict on the other. Evolutionary biologist David Haig, addresses the subject of infant sleep with the intention of illuminating just how little harmony there often is.

Haig is at pains to emphasise that the ‘best possible outcome’, in terms of genetics, is not necessarily the one that makes us healthiest and happiest but just fit enough to keep the gene alive and to pass it on. For him the fact that birth and labour are so difficult and dangerous can’t possibly have evolved as a result of the perfect harmony between mother and child. Evolution does not produce ideal outcomes. He states that the reason babies who breastfeed wake a lot is not because the milk is less satisfying than cow’s milk or formula but because a tired mother is less likely to have another baby and thus the infant will get maximum care. If it’s being bottle fed then waking will not necessarily involve the mother nor will the mother be expending any extra energy in producing the milk herself, so waking is less functional. In fact even breast fed babies who aren’t fed at night tend to sleep better, once the baby is not waking the mother then it stops waking up. So goes the theory.

Babies have inherited genes from multiple sources and those from their mother and their father can sometimes work at cross purposes. As Haig puts it ‘The architecture of infant sleep can be likened to a ramshackle structure put together by a committee from contradictory plans’. The father’s genes want to make sure the baby has maximum chance of surviving. The mother’s genes prioritise her own survival as well as the chance to have more babies. If the baby has more of the father’s genes it will wake more to maximise it’s own chances, if more of the mother’s then it will wake less to maximise her fitness. The mother’s gene doesn’t need the baby to be happy and healthy, just fit enough so that she can go on to have more.

This is not a picture of harmony but one of conflict between competing genes. The whole article, which really is fascinating, is roughly saying sleep training might be bad and feeding at night might be more valuable than we realise but we don’t know for sure yet and we do plenty of other unnatural things that go against our biologically evolved natures, like using contraceptive, so let’s not beat ourselves up about it. As he puts it:

‘There is no lost Eden of perfect harmony between mother and child. What was best for one was not always best for the other. They never were one body and one flesh. Genetic conflicts within the family are part of our biological heritage, as are love and care for our children. The comforting news is that child well-being is unlikely to be irrevocably compromised by minor variations in parental care.’

Do I agree with all this? Not really. And I’ve read a competing theory from another evolutionary biologist who makes use of anthropological data and much more detailed infant sleep research that I am more convinced by but I do like having my beliefs challenged and reading new ideas which is the idea of this blog. Plus, the notion that conflict is also a natural part of parenting is indeed very comforting.

David Haig’s article is here. 

James J. McKenna counters this article directly here. 

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