The Long Lives of Primates and the 'Invariant Rate of Ageing' Hypothesis

Is it possible to slow the rate of ageing, or do biological constraints
limit its plasticity? We test the ‘invariant rate of ageing’ hypothesis,
which posits that the rate of ageing is relatively fixed within species,
with a collection of 39 human and nonhuman primate datasets across seven
genera. We first recapitulate, in nonhuman primates, the highly regular
relationship between life expectancy and lifespan equality seen in humans.
We next demonstrate that variation in the rate of ageing within genera is
orders of magnitude smaller than variation in pre-adult and
age-independent mortality. Finally, we demonstrate that changes in the
rate of ageing, but not other mortality parameters, produce striking,
species-atypical changes in mortality patterns. Our results support the
invariant rate of ageing hypothesis, implying biological constraints on
how much the human rate of ageing can be slowed.