Using modern forensic technology and a decidedly modern understanding of biochemistry, researchers from The University of Western Ontario have taken a look at stress levels in pre-Colombian Peru; their findings are summarized in an upcoming edition of the Journal of Archaeological Science. They found that stress has plagued humanity for at least 1500 years. The researchers were able to get the dead to give up not only their final secrets, but an understanding of their life for a few years before they shuffled off this mortal coil.
When humans get stressed, our bodies release a chemical known as cortisol, which appears in our blood, our urine, and even our hair. Of those three, hair is only one stands the test of over 1000 years of time, and provides a short history of the last years that its owner had. By examining hair strands from 10 individuals at five different dig sites in Peru, the researchers were able to determine how stressed people were, using the levels of cortisol in segments of their hair.
Ars Technica: The prehistory of stress