> I was unable to find the paper the article claims was published about this, which is a shame because I'd love to learn more about what the researchers actually said.
https://www.ncbi.nlm.nih.gov/books/NBK6486/
It's been a while since I looked into this. The (simplified) AAAA at the end of a DNA strand gets shorter and shorter upon each reproduction, kinda like an aglet, holding things together until it is too short, and then the strands unwind and get knotted in counterproductive ways, creating unintentional proteins, etc, resulting in disease and eventually death. Our immune system typically notices this happening, and kills off those cells first. Eventually it gets out of control, and population density is maintained.
Evolution-wise, this kills off the individual sooner. Population-wise this maintains the population strength since it lowers the energy competition (food, etc) and keeps it balanced.
Evolution has very little to do with individuals. It has everything to do with what gets added or subtracted from the population as a result of its appearance and spread within the population.