Leukocyte Telomere Length and the Father’s Age Enigma: Implications for Population Health and for Life Course

What are the implications for population health of the demographic trend toward increasing paternal age at conception (PAC) in modern societies? We propose that the effects of older PAC are likely to be broad and harmful in some domains of health but beneficial in others. Harmful effects of older PAC have received the most attention. Thus, for example, older PAC is associated with an increased risk of offspring having rare conditions such as achondroplasia and Marfan syndrome, as well as with neurodevelopmental disorders such as autism. However, newly emerging evidence in the telomere field suggests potentially beneficial effects, since older PAC is associated with a longer leukocyte telomere length (LTL) in offspring, and a longer LTL is associated with a reduced risk of atherosclerosis and with increased survival in the elderly. Thus, older PAC may cumulatively increase resistance to atherosclerosis and lengthen lifespan in successive generations of modern humans. In this paper we: (i) introduce these novel findings; (ii) discuss potential explanations for the effect of older PAC on offspring LTL; (iii) draw implications for population health and for life course; (iv) put forth an evolutionary perspective as a context for the multigenerational effects of PAC; and (v) call for broad and intensive research to understand the mechanisms underlying the effects of PAC. We draw together work across a range of disciplines to offer an integrated perspective of this issue.