Death Of Old Age Explained

Among the things that Dawkins explains in chapter 3 of The Selfish Gene is death of old age. I've often wondered why exactly it is that everything, including humans, dies of old age. Dawkins explains that this is because of lethal or semi-lethal genes that rise up after our reproductive years. This poses a theorietical way of living longer except that it is only theoretical.
I also really liked what Dawkins says about genes and teamwork. A gene that is good for survival and reproduction doesn't make it along by itself but rather gets along because it is good in a group. Although I don't believe this was the intention, this is telling us how humans should behave. Although selfishness is the fundamental quality a gene should have, it only survives so long because of its ability to work in its group of chromosomes. Likewise, as much as we strive for personal success or happiness or whatever, we will only truly achieve it in group.