My last grandparent just died (of old age - a sequence of maladies, rather than one dramatic accident). Goodbye, Nana.

Telomere length is thought to be better indicators of time until “death of natural causes” than chronological age. They’re some apparently non-informative parts of our DNA that are like end-caps - taped-off ends of rope, or lead-in silence on an analog tape, that for whatever reason tend to shrink over time (with # of cell divisions? oxidative stress?). Small enough telomeres ensure that the cell will have a limited number of offspring, assuming constant loss per division - probably an anti-cancer mechanism (if cancerous cells divide rapidly, then they’ll run out of telomere).

This paper studied bird deaths on an idyllic predator-free island.

Telomere length, not age, predicted short term death.

There were large variations in telomere length at various ages:

In any case, there’s nothing to tell us that short telomeres *cause* death, but they certainly at least reflect things that cause it (for one: age).

What’s really new in this study is that they repeatedly measured the same (bird) individuals and found that telomeres shrank at different rates for different individuals (higher rate of decline being associated with health markers). ┬áNot only absolute length, but rate of decline (quite unsurprisingly given the earlier association) predicts death. Further, they showed that young short-telomere individuals are also likely to die (overall, and especially in that same year - oddly, long- and short- telomered birds who survived any given year had about the same life expectancy). This slightly suggests that a low *rate* of shrinkage is what predicts long life (that, given you live out this year, what challenges came before may not matter), but unfortunately there aren’t enough measurements to look for small effects based on slope.

It seems the 200 individual birds studied over 20 years, while being the cleanest longitudinal data I’ve heard of, aren’t quite enough to tell us if we should interpret shorter-than-average telomeres as a sign of anything we wouldn’t already know by looking at a person (but that doesn’t stop some company selling human telomere measurements for $500 - I’d want an audit showing they actually do the lab work rather than just returning a random number centered around your age).