individual’s life experiences as well as by gene expression, and the gene expression
—affected by early developmental experiences, including maternal care—may be
epigenetically passed on over generations (Meaney 2001 ). There is mounting
evidence that stress exposure in early life leads to epigenetic changes that are
manifested throughout the rest of an individual’s life and perhaps passed down
epigenetically to later generations (Hunter 2012 ; Vaiserman 2014 ).
Studies have been carried out that have used stress measures as a tool to
understand how people react to circumstances in their daily life. These studies have
as their primary goal understanding human experience, as opposed to understanding
stress per se. This goal of understanding human experience becomes particularly
difficult when attempting to understand experiences across cultural differences.
A few examples will have to suffice to introduce this work, including research
through the life cycle.
Early experiences have a great effect on stress reactivity and chronic stress levels
throughout life, and therefore studies of children during normal activities is critical
to understanding human stress responses. A remarkable study by Mark Flinn and
coworkers surveyed hundreds of children over a 20-year period on the island of
Dominica, with over 100 salivary cortisol samples obtained from each child. The
study showed that family environment was by far the most important predictor of
stress in the children (Flinn and England 1997 ; Flinn 2009 , 2010 ). Catherine
Panter-Brick and colleagues carried out a study comparing children in Nepal who
lived in traditional rural villages,“street urchins”in Katmandu, and middle class
children in Katmandu. High cortisol levels were associated with slower growth
rates, and while, as expected, the middle class children had the lowest cortisol
levels, it was surprising that the street urchins had lower salivary cortisol levels, and
faster growth rates, than the children in traditional settings (Panter-Brick 2002 ;
Worthman and Panter-Brick 2008 ).
Adolescence is a time of stress (including for parents) as neurological devel-
opment and the transition to adulthood leads to increased experience of stress by
many teens (Arnett 1999 ; Spear 2000 ). Adolescence is a time when major shifts in
social status occur; changes in status lead to uncertainty and feelings of less control,
both of which are hallmarks of stress. Status changes comprise many of the items
on life events checklists that measure stress. When adolescents are also a part of a
population that is undergoing culture change, this stress may be heightened.
A study by McDade in Samoa has shown that adolescents faced with“status
incongruity” (where there is a disconnect between traditional and modernized
statuses) have a greater downregulation of their immune systems, as measured by
Epstein–Barr virus antibodies in blood spots, that serves as a biological marker of a
stress response (McDade 2002 ).
Studies have also examined stress in the elderly. These studies take on impor-
tance because of evidence that increased stress as measured by catecholamine
excretion is a predictor of increased risk for both heart disease and cognitive decline
(Carstensen, et al. 1995 ; Reuben et al. 2000 ; Karlamangla et al. 2005 ). In general,
older adults often respond more slowly to stress, may have an elevated response,
and take longer to recover from the stress (Ice 2005 ; Williams 2007 ). In a study of
7 Stress Biomarkers as an Objective Window on Experience 129