In Part 1 of our menopause series, we explore two fundamental questions: Why does menopause exist, and what physiologic changes drive the menopausal transition? Topics include: Definitions of perimenopause, menopause, and postmenopause Why humans are unusual among mammals in having a long post-reproductive lifespan The Mother and Grandmother hypotheses Chimpanzee and whale comparisons Oocyte development and follicular depletion AMH, inhibin B, FSH, and ovarian aging The hypothalamic-pituitary-ovarian axis Why menstrual cycles become irregular during perimenopause The physiologic foundation for menopausal symptoms This episode lays the groundwork for future discussions of vasomotor symptoms, mood changes, hormone therapy, and modern menopause management. References Williams GC. Pleiotropy, natural selection, and the evolution of senescence. Evolution. 1957;11(4):398-411. doi:10.1111/j.1558-5646.1957.tb02911.x https://doi.org/10.1111/j.1558-5646.1957.tb02911.x Hamilton WD. The moulding of senescence by natural selection. Journal of Theoretical Biology. 1966;12(1):12-45. doi:10.1016/0022-5193(66)90184-6 https://doi.org/10.1016/0022-5193(66)90184-6 Hill K, Hurtado AM. Ache Life History: The Ecology and Demography of a Foraging People. New York, NY: Aldine de Gruyter; 1996. Hawkes K, O'Connell JF, Blurton Jones NG, Alvarez H, Charnov EL. Grandmothering, menopause, and the evolution of human life histories. Proc Natl Acad Sci U S A. 1998;95(3):1336-1339. doi:10.1073/pnas.95.3.1336 https://doi.org/10.1073/pnas.95.3.1336 Thompson ME, Jones JH, Pusey AE, et al. Aging and fertility patterns in wild chimpanzees provide insights into the evolution of menopause. Curr Biol. 2007;17(24):2150-2156. doi:10.1016/j.cub.2007.11.033 https://doi.org/10.1016/j.cub.2007.11.033 Jones KP, Walker LC, Anderson D, Lacreuse A, Robson SL, Hawkes K. Depletion of ovarian follicles with age in chimpanzees: similarities to humans. Biol Reprod. 2007;77(2):247-251. doi:10.1095/biolreprod.106.058156 https://doi.org/10.1095/biolreprod.106.058156 Faddy MJ, Gosden RG, Gougeon A, Richardson SJ, Nelson JF. Accelerated disappearance of ovarian follicles in mid-life: implications for forecasting menopause. Hum Reprod. 1992;7(10):1342-1346. doi:10.1093/oxfordjournals.humrep.a137570 https://doi.org/10.1093/oxfordjournals.humrep.a137570 Faddy MJ, Gosden RG. A model conforming the decline in follicle numbers to the age of menopause in women. Hum Reprod. 1996;11(7):1484-1486. doi:10.1093/oxfordjournals.humrep.a019425 https://doi.org/10.1093/oxfordjournals.humrep.a019425 Broekmans FJ, Knauff EA, te Velde ER, Macklon NS, Fauser BC. Female reproductive ageing: current knowledge and future trends. Trends Endocrinol Metab. 2007;18(2):58-65. doi:10.1016/j.tem.2007.01.004 https://doi.org/10.1016/j.tem.2007.01.004 Burger HG, Dudley EC, Robertson DM, Dennerstein L. Hormonal changes in the menopause transition. Recent Prog Horm Res. 2002;57:257-275. doi:10.1210/rp.57.1.257 https://doi.org/10.1210/rp.57.1.257
