There’s little doubt, (none on my part), that telomeres play an important role in aging. There’s also no doubt that that different genes are expressed when telomeres are shortened to critical length and no doubt that the genes in sub-telomeric regions are differently expressed under telomere attrition. So is telomere length an important determinant of aging? Yes. Is it the cause or consequence of aging – that’s another story entirely? My take is that telomere attrition is part of the aging process; telomeres losses are NOT the result of the ‘end-replication’ problem- not an inevitable consequence of the natural inadequacies of lagging-strand DNA synthesis: the cell can rebuild its telomeres at any time (as do young stem cells), but chooses not to. This is one of the many post-adult life-stage developmental clocks (which occur at all levels of the biological hierarchy), telling us that it’s time for ‘phenoptosis’ – the sacrifice of the individual for the good of the species.