> This convergence hints aging may not be a diffuse “wear and tear” process
About this: it seems to me that the idea itself of "wear and tear" is just silly. It's a metaphor taken from the realm of mechanical objects that have no regeneration abilities. Any living being is continuously repairing localised damages back to a pristine state, while aging is diffuse and organic. This suggests that any "wear and tear" can only be at the cellular level- but still it can't be a biological necessity given the wildly different lifespans of organisms- from a few days to centuries.
It still applies because while organisms all have some form of self-repair ability, most do not have complete self-repair. "Wear and tear" is still possible at the macro level where self-repair is missing or slower than the damage rate -- famously in the articular cartilage, for instance. There's also accumulating damage that does not resemble mechanical wear and tear: toxins, misfolded proteins, DNA damage/mutation, senescent cells, etc.
Biological entities have some regeneration techniques, but that doesn't guarantee a mechanism exists for arbitrary damage to be repaired. For example I can heal a broken bone, but I can't heal a broken tooth.
No but you do grow entire teeth. Some animals regrow entire limbs. Organisms constantly build and rebuild themselves, sometimes (or at some levels) from scratch. Fresh cells can be generated at any time. The capacity to regenerate and repair can be lost but it's not intrinsically absent as the "wear and tear" metaphor suggests.
About this: it seems to me that the idea itself of "wear and tear" is just silly. It's a metaphor taken from the realm of mechanical objects that have no regeneration abilities. Any living being is continuously repairing localised damages back to a pristine state, while aging is diffuse and organic. This suggests that any "wear and tear" can only be at the cellular level- but still it can't be a biological necessity given the wildly different lifespans of organisms- from a few days to centuries.