There are animals that don't "age"[1] so of course it's programmed. There's a balance between how often you want to recombine genetics and how long you want to be able to remember. It seems like a better system would have humans decline differently (i.e. no dementia) but having people grow old is almost certainly beneficial to the species.
[1] Their risk of death does not increase after reaching adulthood. I.e. every year after adulthood has the same risk of unexpected death. Humans and other animals that age have their risks of death climb in "old" age.
IANAB but lobsters are worth a look. They apparently do not get slower or weaker or even lose fertility as they age. And apparently Greenland Sharks might live for 300-500 years, are immune to cancers, and their DNA can repair itself. Maybe leaving the ocean was our ancestors' mistake.
Greenland sharks are interesting because they do everything slowly, including aging. Our best guess is that pregnant Greenland sharks have at least a decade-long gestation period. Which seems like an adaptation to cold and relatively barren environments?
aeturnum · · focus · HN ↗
[1] Their risk of death does not increase after reaching adulthood. I.e. every year after adulthood has the same risk of unexpected death. Humans and other animals that age have their risks of death climb in "old" age.
manyatoms · · focus · HN ↗
emptybits · · focus · HN ↗
cryzinger · · focus · HN ↗