This 2015 Pennsylvania/North Dakota animal and human review noted:
“The mechanisms linking stress exposure to disease progression and ageing either within individuals or across generations are still unclear, but recent work suggests that telomere dynamics (length and loss rate) may play an important role.
Parental stress may directly influence the parental germline telomeres pre-fertilization, affecting the telomere length inherited by offspring. Alternatively, parental stress may affect telomere dynamics indirectly either pre- or post-natally. The physiological mechanisms by which stress elicits changes in telomere length are also diverse.
We need more information about how these effects vary between developmental stages, among individuals, and within tissues of individuals..to mitigate the effects of early life adversity on human health.”
I was disappointed that the reviewers chose Problematic research with telomere length as a reference. Then again, maybe their statement:
“how these traits are related to one another clearly deserves more study”
is a polite way of saying that study’s methodology was flawed?
Regarding evolutionary biology:
“While most evidence suggests that the effect of parental stress exposure on offspring telomeres is negative, it is important to remember that this is just one trait that can contribute to parental and offspring fitness.
Investment in traits that increase fitness is expected to be favoured, even if they come at a cost to traits associated with longevity, such as telomere length.”
A similar point was made in a reference of A study of DNA methylation and age that:
“Aging has no purpose (neither for individuals nor for group), no intention. Nature does not select for quasi-programs. It selects for robust developmental growth.”
http://rsbl.royalsocietypublishing.org/content/11/11/20150396 “Telomere dynamics may link stress exposure and ageing across generations”