Stress and sex

A study from 2013 that documented sex differences in sleep needs (based on inflammatory markers) turned  my thoughts to stress susceptibility. I recently wrote about allostatic load, a measure of elevated cortisol (a stress hormone) in living human populations. While attempts to transfer the concept of allostatic load to the bioarchaeological record are lacking robusticity, there is a rich history of people writing about odonto-skeletal stress markers and variation within and among populations in the frequencies of these markers.

A commonly cited expectation is that male physiological vulnerability results in higher levels of stress markers unless otherwise culturally buffered by sex-biased investment in offspring. The assumption of sex-based differences in one stress marker (enamel hypoplasias) was reviewed and mostly dismissed by Guatelli-Steinberg and Lukacs (though read the paper to understand the weak effect sex may have in some cases, the data analyzed to make this conclusion, and other subtle findings). Instead, they find that the big effect in the development of sex differences is from culturally based sex-biased investment in children. The sex-bias is hard to show in the archaeological record: in other words, while the biological data may show a sex difference, determining if the differences are from sampling error (burials most often are small in sample size and non-representative) or cultural biases (interpretable often through the material culture record) is extremely challenging. 

According to a growing body of research (perhaps stemming from high rates of heart disease in modern females–number one killer), females have more inflammatory markers in their body and higher rates of inflammation. Inflammation is part of the native immune system and a basic sign of physiological stress. These findings, if they can be applied to past populations, suggest that females are not buffered biologically and archaeological data suggest that more often than not, females are also not buffered culturally.

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