Evolutionary significance of menopause. (Answer in 150 words)

- Evolutionary significance of menopause. (Answer in 150 words)
Introduction
Human females stop reproducing near fifty yet often live decades longer. Only humans and a few toothed whales, notably killer and pilot whales, show so long a post-reproductive lifespan.

Body
1. The puzzle: fitness is counted in descendants, so an allele ending fertility early should be lost unless the forgone reproduction is repaid elsewhere.
2. The competing hypotheses: Hawkes's grandmother hypothesis, from Hadza foraging data, holds that provisioning by older women allows earlier weaning and shorter birth intervals, buying inclusive fitness. Williams's mother hypothesis argues that rising maternal risk with age makes investment in existing children the better bet. Cant and Johnstone derive menopause from asymmetric relatedness in patrilocal groups, where mother-in-law and daughter-in-law breeding together is costly. A fourth view treats it as a byproduct of lengthened lifespan against a fixed oocyte stock.
3. The evidence: grandmaternal presence lowers child mortality in Hadza and Gambian data; Finnish parish records support the conflict model; killer whale matriarchs lead foraging.

Conclusion
No single hypothesis suffices; grandmothering and reproductive conflict together, acting on an ancient follicular depletion schedule, is the best-supported account.