A Natural History of Families. Scott Forbes. TLS January 2006

I would agree with Scott Forbes that any attempt to explain social behaviour without any reference to a Darwinian framework is futile. However using nothing but a Darwinian framework is also unsatisfactory, and as the closing paragraphs of this review make clear, evolutionary psychology’s tendency to just-so stories is something I have always found suspect (I recall reading a very unconvincing paper on experimental methods in some area of evolutionary psychology which I must dig up) . The Huxley quote “in every hedge & every copse battle murder & sudden death are the order of the day” seems germane to some of my recent maunderings on nature writing.

“We are not mice” – slightly too cute as a summing up line. We are biological entities, with our location in the animal kingdom in a phylogeny of our own making and probably masking the continuum nature of species. We are animals, but are we “just” animals?

Again, thanks to Maren Meinhardt for providing me with the published text.

 

A NATURAL HISTORY OF FAMILIES. Scott Forbes. 228pp. Princeton University Press.

Pounds 17.95 (US $27.95). – 0 691 09482 9.

You see a meadow rich in flower & foliage and your memory rests upon it as an image of peaceful beauty. It is a delusion . . . . not a moment passes in that holocaust, in every hedge & every copse battle murder & sudden death are the order of the day.

Thus T. H. Huxley punctured a fond illusion that many hold about “nature”.
A Natural History of Families, Scott Forbes’s account of what behavioural ecologists have learned about family dynamics, is concerned with linking this knowledge to an understanding of human family life. Forbes attacks the perceived arrogance of sociologists dismissive of sociobiological insights:

“The perspective that we can explain human behaviour without a Darwinian foundation -still the distorted view of many in the social sciences -is hubris”, he writes, though he acknowledges that “linking animal to human behaviour is no simple task . . . (and) has not yet helped me in resolving the seemingly endless disputes with my sons”.

In the animal kingdom, parents tend to create more offspring than they can raise to maturity -“parental optimism”. In cases of obligatory brood reduction, at least one offspring invariably dies. For instance, Harpy eagles lay two eggs, and once one has hatched, bury the other. Among Pelicans and Boobies, the first chick to hatch wages a war to the death against the second-born (and therefore smaller) chick. These species practise a form of insurance, reminiscent of the traditional hope for “an heir and a spare”, except with added infanticide. Primogeniture is the human behaviour most obviously similar to the concepts of “core” and “marginal” broods that Forbes discusses. The core brood is the one that survives, while the survival of the marginal is at best a bonus. If something happens to the core, one of the marginal offspring can be promoted and then have a much greater chance of survival.

Infanticide and siblicide may seem, at first, wilful behaviours from an evolutionary point of view. Darwin himself wrote, in The Descent of Man, that “the instincts of the lower animals are never so perverted as to lead them regularly to destroy their own offspring”. Here Darwin nodded, according to Forbes, and both sentimentality and a failure to recognize the true nature of genetic conflict still blind us. Genetic conflict does not occur only between organisms but within organisms. Many phenomena of human pregnancy -for instance, morning sickness, pre-eclampsia and gestational diabetes -Forbes describes in terms of genetic conflict between mother and fetus, or even between the fetus’s own paternal and maternal genetic inheritances.

An astonishing number of human pregnancies are spontaneously terminated, usually before the mother is aware that she may be pregnant. The figure rises from 50 per cent at age twenty-five to 96 per cent at forty. Forbes describes evolutionary reasons for these phenomena, with mothers “screening” their offspring before continuing with pregnancy. Furthermore, many more multiple conceptions occur than multiple births. Forbes suggests that the “vanishing twin” phenomenon is analogous to the brood-reduction phenomena seen more clearly in other animals.

Forbes’s writing is lively and generally clear, though at times rather irritatingly jocular (one tires of references to “mom and dad”). He explains evolutionary theory lucidly and well, though not perhaps clearly enough for an absolute beginner. Some may find that, while his opening chapter uses many examples from the animal kingdom, his later ones lean rather heavily on a more abstract discussion of genetic and evolutionary theory. However, Forbes is good at explaining the subtlety and frequent counter-intuitiveness of current thinking on these topics.

While Darwin is surely essential to an understanding of the complexities of family life, there is more to human family behaviour than primogeniture and infanticide. As with many who seek to apply Darwinian frames to human behaviour, Forbes makes the no doubt true observation that revulsion at the infanticidal practices of the Spartans, and the general sentimentality of the “family myth”, are a consequence of insulation from the rougher aspects of existence. But what does this self-insulation -which seems to be unique to our species -tell us?

Male mice routinely kill off offspring that are not their own. Female mice spontaneously abort unborn pups on smelling a strange male during pregnancy. As is well known, infanticide and abuse of all kinds are more commonly perpetrated by step-parents than genetic parents. But “more commonly” does not mean “commonly”.

We are not mice. Scott Forbes, thankfully, is well aware of this fact.

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