Gwen Dewar, Ph.D.
posted in Mom Stories
Do you give your daughter the same attention and care that you give your son? In many places around the world, girls get second-class treatment, and it’s not necessarily because the parents themselves are hopelessly misogynistic. Some families are better off if they produce warriors or strong laborers. They might have to pay a heavy penalty in the form of a dowry if their daughter marries. Rules of inheritance might demand that a family have sons.
In these situations, daughters can be costly burdens, and society encourages parents to channel their parenting efforts towards boys.
But this isn’t always the case, parental favoritism that shuts out girls. If you try playing God with me – a little thought experiment – you’ll see what I mean.
Suppose we wanted to design a monkey – call her Granny – who will behave in ways likely to get her lots of grandchildren. This means she’ll be well-adapted to her environment – “tuned in” to the best ways to get food, find shelter, avoid predators, and things like that.
It also means she’ll make choices that give her the best return on her parental investments.
She won’t spend all her energy on just one kid (when she could spread it around and have more). Nor will she try to have dozens of babies, overextend herself, and end up with a bunch of poor-quality offspring who don’t survive. She’ll go for the optimal number of kids – the “just right” number that maximizes both quantity and quality.
And maybe she’ll do something else. She’ll look around her, see what it will take for her kids to succeed, and avoid investing extra time and energy in offspring that aren’t likely to reproduce themselves.
For instance, suppose Granny lives in a society where only the biggest, toughest males manage to father offspring? When males, but not females, need to be big to score parenting success, a mother with poor resources might be wasting her time trying to raise big sons. No matter how hard she tries, she’s unlikely to make the sorts of sons who will make it to the top of the social ladder.
But the situation is different if she raises daughters. In this society of intense male-male competition, just about every female manages to reproduce. So Granny – if she has few resources to spare – can best ensure she will have grandchildren by investing more in her daughters.
Do real-life animals ever behave this way – adjust their investment in offspring depending on how likely those offspring are to reproduce?
Biologists Robert Trivers and Dan Willard thought so, and they predicted that animals living in societies like Granny’s would tend to favor whichever sex was most appropriate to their personal resources. Low-ranking mothers in relatively poor condition would invest more in daughters. High-ranking mothers –who have the best access to food and other perks – would focus on raising sons.
The predictions have panned out in some cases – showing, for instance, that females in poor condition make richer milk if their infants are female.
And what about human animals? Some human societies sound a lot like Granny’s, even if the men don’t battle each other tooth and nail. They compete in other ways – by accumulating wealth and prestige – and rich, popular men have many more mating opportunities than their impoverished counterparts.
So Masako Fujista and her colleagues visited one of these societies in Northern Kenya, and asked if mothers are adjusting their investment without even realizing it – by varying the fat content in their breast milk.
Do mothers living at the bottom of the socioeconomic scale produce fatter breast milk when they have daughters, and leaner breast milk when they have sons? Do wealthy moms do the opposite – saving the “good stuff” for baby boys?
The answer, in this study, seemed to be yes. But it’s interesting – and important – to note that mothers weren’t consciously trying to favor one sex based on their socioeconomic status. The researchers didn’t find that poor mothers nursed their daughters more frequently, or that rich moms breastfed more often if they had sons.
And keep in mind: Overall, studies testing the Trivers-Willard hypothesis have had mixed results. Is the hypothesis wrong? Or is it merely that parenting is so complex — and so fraught with dangers and mistakes — that any Granny-like, unconscious strategizing gets washed out by other factors? I tend to think the latter. But in any event, it’s quite fascinating to think our breast milk might vary according to the sex of our children.
Read more from source:“babycenter-com-baby”