The longer you've lived, the greater your chance of already having passed your genes on. A gene that makes you get cancer when you're 10 has never been passed on. The older you get, the more likely you are to be hit by lethal genes which have slipped through the net. This is part of what I was calling good enough. You're good enough. Your eyesight, my eyesight is good enough to get us this far. So there's no sexual selection? Not just sexual selection, but any kind of selection is weaker the older you get because you've already passed the genes on.