- Mother Nature: Natural Selection and the Female of the Species by Sarah Blaffer Hrdy
Chatto, 697 pp, £20.00, November 1999, ISBN 0 7011 6625 8
Sarah Hrdy is tough-minded about a tender subject. Motherhood, she says, is a minefield. Mothers love babies passionately – but not unconditionally. We have evolved as adept sociobiologists, able to calculate love. On the other side of the relationship, baby love is unconditional, indeed desperate. Babies want it all, every scrap of attention they can command, at least up to the point where the mother would be so exhausted that her failure would rebound on the baby itself. Babies cannot be physical tyrants, at their body size, so they resort to psychological tyranny: they are irresistible.
In the 700 funny, erudite and combative pages of Mother Nature Hrdy ranges from wet nursing to attachment theory to why a female executive punches through the glass ceiling. Where her biological arguments in general are concerned, I’ll assume, to leap to the bottom line, that the nature/nurture debate has moved by this time from the theoretical sphere to the technological – soon, the feuding over sociobiology is going to seem pretty trivial. As for Hrdy’s political agenda, her robust analysis goes far towards bridging the gulf between biologists and liberal humanists. It turns out that sociobiology has now joined up with feminism to argue for community spirit and cooperative child care. Childcare enabled human mothers to become human.
Mothers’ and babies’ calculations of love reflect the law proposed by the late William Hamilton, a creative genius of sociobiology. (Hamilton died this year of malaria contracted in the Congo, where he was pursuing his latest ideas on the transmission of disease between species – arguably a martyr to his own passion for truth.) Hamilton reasoned that, by genetic logic, kin should help kin when the benefit outweighs the cost, but help is discounted by distance of relationship. A child shares only half her mother’s genes; the other half of the genetic equation comes from the father. The baby is, of course, wholly itself. Hence the potential conflict: the baby wants everything, even if the mother’s interests are different.
But why should a mother hold back, even a little, from anything as wonderful as her child? If evolution is all about die reproduction of genes, surely the child is her hope of a genes, future? Well, not just this child. She needs to spread her devotion over her whole family, to the toddler(s) already born, and also take into account her chances of having another baby after this one. That means saving enough of herself from the needy newborn, so that she can care for the siblings when they have their noses put out of joint by the new arrival.
It means, above all, taking care of herself. Hrdy points out that in human societies as far apart as the !Kung San hunter gatherers of the Kalahari Desert, and the inhabitants of California’s Sacramento Valley, around 40 per cent of women leave no surviving descendants at their death. Our pre-human foremothers probably had an even lower rate of reproductive success. Perhaps only half the females, in an average generation, left grandchildren. Those who became our ancestresses in each generation were lucky, and strong, and able unconsciously to balance their children’s welfare against their own. A mother who squandered the resources needed to maintain her own health would be quickly weeded out – and her family would probably follow her into oblivion.
On top of physical health, it helped a whole lot to be dominant. Relations with males are a crucial part of the story. In the vast majority of primate species, males routinely dominate females. In a few, like our near relations the bonobos, or distant ones like ringtailed lemurs, females are clearly the dominant sex. In some more monogamous species, the sexes are co-dominant. (You must judge for yourselves where humans fall along this continuum.)
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[*] Oxford, 504 pp., £20, 31 March, 0 19 850505 1.