In a 1989 Canadian study, adults were asked to imagine the death of children of various ages and estimate which deaths would create the greatest sense of loss in a parent. The results, plotted on a graph, show grief growing until just before adolescence and then beginning to drop. When this curve was compared with a curve showing changes in reproductive potential over the life cycle (a pattern calculated from Canadian demographic data), the correlation was fairly strong. But much stronger - nearly perfect, in fact - was the correlation between the grief curves of these modern Canadians and the reproductive-potential curve of a hunter-gatherer people, the !Kung of Africa. In other words, the pattern of changing grief was almost exactly what a Darwinian would predict, given demographic realities in the ancestral environment... The first correlation was .64, the second an extremely high .92.

(Robert Wright, summarizing: "Human Grief: Is Its Intensity Related to the Reproductive Value of the Deceased?" Crawford, C. B., Salter, B. E., and Lang, K.L. Ethology and Sociobiology 10:297-307.)

Disclaimer: I haven't read this paper because it (a) isn't online and (b) is not specifically relevant to my actual real job. But going on the given description, it seems like a reasonably awesome experiment. [Gated version here, thanks Benja Fallenstein. Odd, I thought I searched for that. Reading now... seems to check out on the basics. Correlations are as described, N=221.]

The most obvious inelegance of this study, as described, is that it was conducted by asking human adults to imagine parental grief, rather than asking real parents with children of particular ages. (Presumably that would have cost more / allowed fewer subjects.) However, my understanding is that the results here squared well with the data from closer studies of parental grief that were looking for other correlations (i.e., a raw correlation between parental grief and child age).

That said, consider some of this experiment's elegant aspects:

A correlation of .92(!) This may sound suspiciously high - could evolution really do such exact fine-tuning? - until you realize that this selection pressure was not only great enough to fine-tune parental grief, but, in fact, carve it out of existence from scratch in the first place.
People who say that evolutionary psychology hasn'

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Fenn

Fenn

Fenn

Fenn