Tuesday, July 10, 2012
Evolution, Attachment, and Megafamilies
Like almost everybody else except possibly creationists, I love to speculate about evolutionary psychology. (Is there creationist psychology, by the way? It might be even more interesting.) What fun, thinking about our remote ancestors wandering the Serengeti or painting horses in caves. I think it was in “Reindeer Moon” that Elizabeth Marshall Thomas described women marrying men from a different group and teaching them to have sex face to face—talk about your paradigm shifts!
On the other hand, even while having fun, I acknowledge that a lot of evolutionary psychology is along the same lines as the Just So Stories. It’s only a step from How the Elephant Got His Trunk to How the Human Babies Got to Be Attached to Familiar People. You can’t always work backwards from the present to past causes, because the same cause can sometimes have different outcomes, and a single outcome can have a variety of causes.
All the same, the evolutionary lens provides interesting images when applied to certain topics. Let’s think about emotional attachment of babies to caregivers. It’s easy to see the evolutionary advantage of having toddlers emotionally attached to familiar people-- the attachment works like an invisible playpen. When mothers gathered food in the wild, or cooked on a campfire, or carried water from a distance (as they still do in the developing world), a toddler who ran off or who approached unfamiliar people or animals might well not survive to reproduce. Those who were attached, who stayed near without being supervised closely, and who scurried back to mama when anything strange or startling happened-- they were the ones most likely to survive, and, given that their behavior was genetically determined, the ones likely to pass their traits along to their own offspring, who in turn would survive better than cousins who were bolder.
But what about the claim that babies are really already attached at the time of birth, when they can’t yet get around on their own? In the environment of early adaptation, that would have been a problem, if it had been true. Maternal death rates were high. Even today, in Sierra Leone, the rate of maternal deaths within the 6 weeks after birth is 2000 per 100,000 births, or 2 maternal deaths per 100 births. Deaths of mothers for reasons unassociated with birth were also common, and probably more so for women who had been weakened by childbirth. This meant that by no means all babies could count on being cared for at age 12 months by the same woman who had given birth to them. For those who were orphaned, it was not necessarily easy even to find in a small band another nursing mother who could feed another child. Caring for an orphaned infant would have been made much more difficult if a young baby had experienced grief over separation from the dead birth mother, because grief interferes with feeding as well as sleep and play. The best arrangement from an evolutionary point of view would have been for infants to develop emotional attachments only after months of experience and familiarity with caregivers-- not that caregivers might not die later on, but they would be less likely to do so if they were not experiencing the risks of childbirth-- and this is how things turned out.
Then there are the megafamilies, adoptive and otherwise. Is it likely that human beings would have evolved to care effectively for many young children at the same time? If we’re talking about adoption, there could be two or more children who are actually about the same age-- would this have occurred in the distant past? Is it likely that any family would have, as well as a lot of young children, many older children who could be put to work at child care? The answers to all these questions are probably in the negative.
Poor diets delay puberty, so it may well be that many of our remote ancestors became sexually mature relatively late and therefore had fewer children than they might have had with early maturation. In addition, regular ovulation depends on having quite a high fat level (24% of the body, believe it or not), which would be less likely with limited food supply and high energy demands from exercise. Of children who were born alive, a high infant mortality rate would have carried off large numbers; even in the 19th century in some European countries, the infant mortality rate (proportion of deaths before the first birthday) was as high as 250 per thousand births-- one quarter of the children born. These facts mean that few, if any, of our remote ancestors-- the people from whom we presumably receive our genetic heritage-- ever had a baby every year and saw all those babies live. If they had twins or triplets, or babies with any handicapping conditions, chances are that they exposed some of those babies to the elements and wild beasts, just as many of our less remote ancestors have done. Giving birth to a small number of children, and rearing relatively few of those, was the situation in the environment of early adaptation.
Assuming that human caregiving behavior evolved to suit that early environment (which it may or may not have done), it would seem that we are not likely to have inherited much ability to care for and respond to large numbers of children. Interestingly, some of the research of Mary Dozier of the University of Delaware has suggested that foster parents who have cared for many children in succession are in fact less capable of developing attachment relationships with children than are those who have cared for fewer foster children. The glamorization of large families by the media (and even those are usually 12 or less) does not reflect reality. Even the originals of “Cheaper by the Dozen”, the Gilbreth family, depended on affluence and faithful servants to achieve their good child-rearing outcomes. It is no wonder that when megafamilies meet real challenges in the form of special-needs children the results may be disastrous; it may not be “natural” for humans to have so many children.