The human life span is not that limited: the effect of multiple longevity phenotypes

There is an ongoing debate as to whether or not human longevity is approaching its limits. The debate and its outcome are important since they might affect public policy. We review the evidence presented by both schools. We add our empirical observation that there exist multiple longevity phenotypes, each of which arises from the alteration of fundamental aging processes. The current debate only considers two of the three known mammalian longevity phenotypes. The overlooked phenotype is the delayed onset of senescence phenotype, which can be induced by various interventions, including pharmaceuticals. The existence of multiple phenotypes means that an overview of potential life expectancy outcomes for a species should be based on the analysis of all longevity phenotypes likely to occur in that species.