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And the book's central message?
That motherhood means trade-offs-it always has. And that human mothers need a lot more help rearing offspring than other apes. This is the first book to really come out and say that humans must have evolved as cooperative breeders. Chimps carry and nurse a baby for four, maybe six years, but once the chimp mother weans her baby, it's nutritionally independent. In humans you have this extraordinarily delayed maturation: children in traditional foraging societies are as old as 18 years before they stop needing handouts from adults. The females are not reaching menarche until 14 or 15 and don't give birth until 19 or 20. Think of all the chances there are to die before 19! And when the females do give birth, they're producing the equivalent of litters or clutches because they're having to simultaneously invest in offspring of different age. This is costly, costly reproduction. So how has our species coped? Mothers have relied on assistance from other members of the group-individuals too young or subordinate to breed, older individuals past reproductive age. And the help of these "allo-parents" has been vital. There is no other way to explain how there could have been selection pressure to produce such slow-maturing infants-not in an ape where there is so little evidence for males committed to infant care. What happens if this evolved system of help in human breeding breaks down? It is breaking down. Never before in the history of our species have there been so many unwanted or neglected children. And more to the point, never before have so many of these children survived to breeding age. In the US, we're pouring money into building prisons, yet there is only a pittance for child daycare. I have a wildly speculative argument about all this that I left out of the book. I am convinced that current child-rearing practices jeopardise the future of the species, not in the sense that the species will die out, but in the sense that we are altering the conditions under which natural selection can operate. People who grow up without committed kin are less likely to develop along the usual path. They're more likely to be narcissistic, not so able to put themselves in another person's shoes, and in extreme cases, unable to feel any empathy at all for other people. Why does this affect natural selection? Because natural selection cannot operate on developmental potential. It can only work on developmental outcomes-on phenotypes. People may have an inborn potential to develop compassion, and compassion may be advantageous in all sorts of ways, but if these potentials remain unexpressed in phenotypes, there is no way natural selection can favour them. What might be the consequences? If compassion only develops under certain conditions, and those conditions become increasingly rare, then tens of thousands of years from now we might have a species that is certainly very clever, much better at tasks such as devising ingenious software, but diminished in its capacity for the sort of intelligent compassion that's uniquely human. In other words, a species that is not human as we currently define ourselves. |