All organisms die, but not all organisms degrade at the same rate. In some species, death rates accelerate over a short period at advanced ages; others exhibit a slower, sustained loss in population numbers over the course of their lifespans. The term “senescence” describes these patterns as a function of physiological declines that occur with age. For decades, the general pattern of senescence – accelerated late-life mortality – was thought to be the standard rule of life. In the early 1990s, the universality of this thinking was called into question. In the 2000s, plant demographers motivated a more definitive case that patterns in birth and death rates were more diverse than previously recognized. Read more