An Epigenetic Signature of Species Maximum Life Span
Self evidently, differences in species life span are determined by genetic differences. It is intriguing, however, to see that it is possible to produce an epigenetic signatures of species life span in mammals. Epigenetic marks on and around the genome determine gene expression, the degree to which a given protein is produced from a given gene sequence. That an epigenetic signature of maximum life span can be determined in mammals indicates that differences in the expression of specific genes (most likely many, many specific genes) are an important component of species longevity, even in cases where the proteins are very similar in structure and function between species, and even given that these epigenetic differences must ultimately descend from differences in the genome.
By analyzing 15,000 samples from 348 mammalian species, we derive DNA methylation (DNAm) predictors of maximum life span (R = 0.89), gestation time (R = 0.96), and age at sexual maturity (R = 0.85). Our maximum life-span predictor indicates a potential innate longevity advantage for females over males in 17 mammalian species including humans.
The DNAm maximum life-span predictions are not affected by caloric restriction or partial reprogramming. Genetic disruptions in the somatotropic axis such as growth hormone receptors have an impact on DNAm maximum life span only in select tissues. Cancer mortality rates show no correlation with our epigenetic estimates of life-history traits.
The DNAm maximum life-span predictor does not detect variation in life span between individuals of the same species, such as between the breeds of dogs. Maximum life span is determined in part by an epigenetic signature that is an intrinsic species property and is distinct from the signatures that relate to individual mortality risk.