Telomeres are noncoding sequences of DNA that form caps at the ends of eukaryotic chromosomes. Some studies in a number of vertebrate species have reported that individuals with longer telomeres have a longer life span. It has been suggested that the observed variation in telomere length among individuals of the same age may play a causative role in determining the rate of aging and age of death. Studies examining this relationship have measured telomere length and survival at a single life-stage (early or late in life) and/or monitored survival over a short period of the life span. Telomere attrition (reduction in length) may be greatest during early life stages of growth and development. It is unclear whether individuals with relatively long telomeres early in life have a greater total life expectancy or whether data are biased when only relatively old individuals are sampled. It is possible that telomere length monitored from early life in normally aging individuals can predict life span.
To test this possibility, this study examined the relationship between telomere length in a group of zebra finches (n = 99) early in life (25 days) and at various points during their natural life span (ranging from <1 to almost 9 years). The effect of reproduction on adult telomere length was also measured.
Telomere length at 25 days was a strong predictor of longevity (P < 0.001). Birds living the longest had consistently longer telomere lengths at all measurable time points. Although reproduction increased adult telomere loss, the effect appeared transient and was not predictive of survival.
These findings show a clear relationship between telomere length early in life and total life span, suggesting that measurement in early life may be a highly significant predictor of the age of death in this population.