Immortality vs. Negligible Senescence

Senescence

“growing old” or “aging”; a time-correlated decline in strength, mobility, fitness, reproductive capacity, etc as well as increase risk of death

Negligible Senescence

mortal, but never “gets old”; mortality rate is not positively correlated with age; reproductive rate is not negatively correlated with age

Mutation Accumulation

genes that only express their deleterious effects later in life are masked by the selection shadow which leads to …

Antagonistic pleiotropy

conflicting effects of genes at different stages of life, beneficial when yong but deleterious when old

Why do we Age?

Genes with late-life effects are passed on to offspring before the later effects are “seen” by natural selection