First the link to this week’s complete list as HTML and as PDF.
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In their comparison Beltrán-Sánchez et al. stress the higher male mortality rate in late middle and early old age and try to find reasons for it. The relative rates for individual causes of death that they look at are meaningless and rise just because people stop dying from other causes. They totally fail to look at absolute age-specific rates. Over the time span they look at both male and female life expectancies have risen substantially, but female ones nearly twice as much as male ones. So the real abnormality here and the thing really to look at and explain are the low female death rates in the age range in question. It is a well known and well documented fact that life expectancy depends weakly on sex but very strongly on occupation with the extremes of publican and protestant pastor divided by a factor of two. With the rise of industrialisation, far better housing, and household appliances the life of housewives has become immeasurably easier after the children have reached adolescent age while professional demands tend not to let up with the beginning decline in performance and thus get relatively harder. This is confirmed by their supplementary figure 1, where it is the female death rate and life expectancy curves that deviate from their long-term trend right when the m/f-ratio begins its steep rise, while the male ones continue unchanged. I expect this trend to reverse for later age cohorts when women began to enter the rat race in large numbers, although there is a tendency for them to prefer the less demanding jobs.
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Nemet et al. as cited by Steckel et al. state a triviality. At a given time with a given set of machines and plants any reduction of energy use and CO2 emission will result in a proportional reduction of pollutants. This is simple and obvious but completely irrelevant for Steckel et al., who discuss the outcomes for different trajectories of industrialization. Going from simple open hearths and furnaces to a much increased use of electricity will strongly increase fuel demand and CO2 emissions while at the same time appreciably lowering pollutant emissions. The resultant expected cost benefits are simply not there.
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Jones & Tuljapurkar offer an alternative to or at least an enhancement of the grandmother hypothesis. If there is an age from when on the benefits of additional fertility are smaller than the survival cost for existing children, a menopause makes sense even from a two-generation perspective. The curves in their figure 3 suggest just that for humans but not for apes.