>>22911373 (OP)The reason we die of old age is because if we didn't, we'd die of cancer, likely in the womb before we were even born.
Every time a cell divides, the DNA also divides. Each daughter cell gets half a strand, and an enzyme rebuilds it. Once both cells have a full DNA strand, they are ready to divide again.
But each time the DNA strand splits, a piece is torn off each end. This would be catastrophe if information was lost. But there are around 100 genes - repeating TG sequences - that don't code for anything. There is no 'start' code at the beginning. These are sacrificial genes we call 'telomeres'.
Once these telomeres are reduced to one or two left, the cell refuses to divide anymore. It works fine, it just becomes unavailable for division.
This protects against a damaged cell that cannot detect it's neighbors, triggering it to begin dividing when the neighbors are actually there. If the cell also cannot suicide when the body orders it to (apoptosis) it can quickly turn cancerous. The final prevention is those telomeres. Many of us, perhaps most, have skin tags, birthmarks, moles, and other signs that certain cells went rogue and were only stopped by the daughter cells running out of telomeres.
We go from one fertilized cell to about ten trillion in only nine months in the womb. Shit is going to go wrong with that many divisions. And it does. Many times. But we don't die of cancer because we're protected by those telomeres.
The cure for dying of cancer is dying of old age. When most of the cells in our bodies will no longer repair tissues, we wrinkle, get brittle bones, dim eyesight, stooped backs, grey hair, then the flu kills us. This is the price we pay for being able to survive long enough to have offspring. Evolutions gives zero fucks what happens to the individual after they've reproduced.
Some design, huh?