The hypothalamus knows when it's time to die. So it is said to excrete a hormone for initiating mass cell death during times of excess, holding back on it during hard times. (Sensing somehow that the whole herd may go down, the gland tries then keep the individual soldiering on for the future.) But with people, a variety of psychological factors ameliorate that. Because for some reason, individuals actually live longer in the lands of plenty. So Maybe, deep down, we believe we're already standing on the edge of an abyss?

That's my theory. But for the record, keep your monkey glands sending out the GnRH, and hold off on the NF-kappa-B!