Whose life is it, anyway?
Elaine Morgan continues her outside-the-archetype thinking so strikingly begun in The Descent of Woman (1972); in The Descent of the Child: Human Evolution from a New Perspective, she presents still more surprises, under our feet as it were.
A generation ago it was still common for books about the evolution of our species to be based on the tacit assumption that the archetypal human being was a male. ...
To a large extent this has been corrected. ...
However, one form of unconscious bias is still operative. If we are asked to envisage an archetypal human being ... it will almost certainly be an adult. We take it for granted that adulthood is the meaningful part of our existence, and everything prior to it is merely preparation. We speak of 'life cycles' in other connections, but we do not think cyclically about human life. We think of it linearly and hierarchically. The old adage quoted by Samuel Butler is often cited but has not yet been fully assimilated: 'A hen is an egg's way of making another egg.' It is very difficult for any of us to think of ourselves as a baby's way of making another baby.
Morgan starts with the process of natural fertilization and works through the stages of zygote, embryo, birth, infant, toddler, and talking pre-schooler; with a look at the peer group and the family. Each of these stages has its own evolutionary history. Each is optimized as much for itself, its own level of development, as it looks backward or forward to earlier or later stages.
We also have co-evolution among the various stages, or among related humans in different stages. In a fascinating chapter, "Brain Growth — the Solution", Morgan discusses the opposing drives toward babies with larger brains, versus their mothers with limited pelvic spread to birth such babies.
It was bipedalism that threw a spanner in the works.
One method of responding to the problem is by developing pelvic dimorphism — the female pelvis becomes differently shaped from the male's. This was the solution resorted to by the New World monkeys. The ones which show the greatest degree of pelvic dimorphism are the ones with relatively bigger heads. This course was also adopted by our ancestors. Pelvic dimorphism — which is trifling in the African apes — is greater in Homo sapiens than in any other primate except the squirrel monkey. But there was a limit to how far it could go. The main effect was to insulate the male from the problems of the female rather than to solve these problems. ...
Two other compromises were introduced — one by the mother, making the pelvic ring temporarily larger, and the other by the baby, making its skull temporarily smaller. ...
However, the permanent solution to the problem was a kind of coup d'etat by the mothers, who took to evicting their babies prior to the state of maturation which constitutes 'full term' in monkeys and apes. This was not at all the same device as that employed by the Shetland pony; her foal was delivered mature and perfectly formed, although miniaturized. The process in the hominids was something more like spontaneous abortion at a late stage of gestation. It must have begun by very slow and gradual stages, for normally, in the wild, infants born prematurely would not survive. Perhaps the infants were aided by their subcutaneous fat layer, which would provide some degree of insulation against friction as well as against cold.
Once this process had begun, it continued. The baby continued its drive to grow larger; the mother countered by evicting it at an earlier and earlier stage of its development without shortening the period of gestation, so that its prenatal growth was able to slow down. At each step in this process, the willingness of the mothers to care diligently for these increasingly helpless offspring would become greater, because the mothers who failed to respond in this way would leave no descendants.
The consequences if this solution to the obstetric dilemma were immense and far-reaching. The brakes on relative brain growth were removed. The rapid growth of brain size — normally only found in unborn mammals — was able to continue unchecked on the safe side of the pelvic bottleneck.
We live with this outcome every day, its ramifications are not only in our bodies. If this absolutely critical challenge had not been solved with reasonable success, culture could not have been invented and transmitted. Proto-humanity would still be fearfully wandering the veldt, eating wild seeds and hoping to catch rats.
I hope this truncated version of Elaine Morgan's analysis of perhaps the most humanly distinctive and visible evolutionary crux between mother and baby, sufficiently suggests why I think The Descent of the Child is so thought-provoking and ultimately satisfying. There is much material in the book. Her thinking is creative and synthetic, her prose is clear, and her account engrossing. Very enjoyable, on several levels.
A personal afterword.
There are vast riches in our lives that should not be abandoned because we "outgrew" them. When I was very young I made myself a promise that when I grew up, I wouldn't forget what it was like to be young: my grown-up self would remember and acknowledge my boyhood self. Although those days have receded into the distance, yet many moments and passages remain warm and dear to me: sunny adventures, and family by firelight, and long twilights running up and down the darkening green. As best I could, I've kept that promise.
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