Some evolutionary biologists attribute menopause to an adaptation toward collective child rearing. As in, a female ages to a point that there has been enough damage (through environmental factors and time) to the quality of genetic material in the eggs that they are no longer viable or produce defective offspring (growing a human baby for 9 months also comsumes far greater energy reserves than a clutch of eggs, so the metabolic cost is much higher for the human). Since humans tend to live in colonies, the biological role of that female shifts from energy going into reproducing her genetics to energy caring for the offspring of her offspring (thus still caring for young, and protecting her genetic legacy). Since BPs don't raise their own young or live in family groups, there is no biological incentive to stop reproducing.