An ingenious technique, just published in the Journal of Archaeological Science, was used to look at patterns of stress in their lives of long-dead people from Peru, some who lived more than a thousand years ago.
The study analysed strands of hair from bodies dug up from five archaeological sites for traces of the hormone cortisol – known to be released when we experience stress.
Hair grows about a centimetre a month and as the body creates the hair, it incorporates traces of chemicals that are present at the time. This means it is possible to look back over the length of a strand of hair and see which chemicals were affecting the person’s body at the time when that bit of hair was formed.
This is the basis of drugs tests that analyse hair for substances like heroin and cocaine, but a few years ago it was discovered that cortisol also left its mark.
A team of researchers, led by anthropologist Emily Webb, took this idea and applied it to the hair of long-dead people from ancient sites across Peru to see how stress affected their lives in the months and years before their deaths.
The researchers found that, in general, stress increased in the months leading up to death – perhaps suggesting death through chronic illness or maybe that the individuals were aware of their impending demise.
The results also showed that in some individuals, stress could suddenly drop for certain periods, perhaps for a month at a time, whereas for others the patterns of stress seemed to go in cycles.
What this does suggest is that then, as now, while there are clearly some things which tend to stress us all, many stress responses are highly changeable and probably quite individual.