Maybe. But whales don’t get cancer either, and whale metabolism is… impressive (well their resting heart rate is lower than ours but they grow orders of magnitude faster, to a point, and sustain themselves gorging on literal tons of food).
> I wonder if whales survive to an equivalent of human old age (where we can be pretty fragile and still survive for decades).
They do and this is well-documented. They're one of the few (only?) other species where we can directly see the role matriarchs (grandmothers, either past their reproductive ages or even undergoing menopause) have on the development of the youth, and it's been used to explore the role of living post-reproductive ancestors might have on natural selection (which was previously not thought to be affected by it).
Maternal grandmothers have even been found to ~spontaneously regain their milk to help nurse infant whales, iirc.
Humans commonly have grandchildren in their 40s (less so recently of course). We get fragile in our 70s. I'm wondering about living decades in that fragile state, where cancer happens to be a lot more common.
That mostly doesn’t count, since humans still regularly have kids of their own in their forties (so the direct link to natural selection would overshadow any lower-pressure grandmotherly effects), so you’d have to push the window out to the post-menopausal period, which coincides with the period in which various cancers begin to be an issue.
