The Postmenopausal Longevity Paradox and the Evolutionary Advantage of Our Grandmothering Life History

Kristen Hawkes, PhD is a Distinguished Professor at the University of Utah, where she has taught in the Department of Anthropology for over four decades. She is also a collaborative scientist with the Yerkes National Primate Research Center and has authored over 120 scientific publications. She lectures internationally on our grandmothering life history and menopause as a uniquely human evolutionary advantage.

On this podcast, Dr. Hawkes discusses the grandmother hypothesis and the environment that likely propelled human evolution. When savanna youngsters couldn’t yet manage to feed themselves, grandmothers were there to help forage,  supporting dependent grandchildren as their own fertility was ending. In the meantime, still-fertile females could invest less in each offspring and have more babies sooner. More robust older females could subsidize more descendants, favouring mutations that enhanced postmenopausal longevity. The research of Dr. Hawkes and her colleagues can help us better understand the critical role of intergenerational support, and how modern individualism has caused us to veer off track.

Here’s the outline of this interview with Kristen Hawkes:

[00:01:22] Becoming interested in grandmothering.

[00:04:17] James O'Connell, Kim Hill, PhD, Eric L. Charnov.

[00:16:00]  The economics of the grandmother role.

[00:17:10] Chimpanzee babies learn to forage and feed themselves while nursing; Studies: Bădescu, Iulia, et al. "A novel fecal stable isotope approach to determine the timing of age‐related feeding transitions in wild infant chimpanzees." American journal of physical anthropology 162.2 (2017): 285-299; and Bray, Joel, et al. "The development of feeding behavior in wild chimpanzees (Pan troglodytes schweinfurthii)." American journal of physical anthropology 165.1 (2018): 34-46.

[00:20:01] Book: Life History Invariants: Some Explorations of Symmetry in Evolutionary Ecology (Oxford Series in Ecology and Evolution), by Eric L. Charnov.

[00:22:19] Mathematical biologist Peter Kim. 

[00:26:33] Why humans are unique amongst primates: Slower development and earlier weaning.

[00:31:49] Cognitive neuroscientist Barbara Finlay.

[00:34:28] Anthropologist Sarah Hrdy; the cognitive ecology of human babies.

[00:36:14] Nancy Howell, demographer for the Harvard Kalahari Project.

[00:38:18] Life expectancy statistics based on an average; childhood and infant mortality historically skews results.

[00:38:33] Demographic studies of foraging populations; Books: Ache Life History: The Ecology and Demography of a Foraging People (Foundations of Human Behavior) by A. Magdalena Hurtado and Kim Hill; 

Demography of the Dobe !Kung (Evolutionary Foundations of Human Behavior), by Nancy Howell; Demography and Evolutionary Ecology of Hadza Hunter-Gatherers, by Nicholas Blurton Jones.

[00:39:27] Life expectancy data, by country; Study:  Oeppen, Jim, and James W. Vaupel. "Broken limits to life expectancy." (2002): 1029-1031.

[00:42:36] Estrogen and hormone replacement therapy.

[00:44:35] Estrogen is converted from DHEA, DHEAS after menopause.

[00:47:17] High testosterone is missing among the Ache of Paraguay; Study: Bribiescas, Richard G. "Testosterone levels among Aché hunter-gatherer men." Human Nature 7.2 (1996): 163-188.

[00:48:36] Evaluating menopausal symptoms in different populations; Lynnette Leidy Sievert.

[00:52:16] Having a grandmother vastly increases chances that a child will survive.

[00:53:51] Female fertility begins to decline in late 20s.

[00:54:11] Utah Population Database for Utah demographic information.

[00:56:12] Book: Mothers and Others: The Evolutionary Origins of Mutual Understanding, by Sarah Blaffer Hrdy.

[01:00:07] Cognitive skills: orangutans, chimpanzees and human children; Study: Herrmann, Esther, et al. "Humans have evolved specialized skills of social cognition: The cultural intelligence hypothesis." science 317.5843 (2007): 1360-1366.

[01:02:34] The Infant Cognition Center at Yale;  Babies prefer individuals who help to one who hinders another; Study: Hamlin, J. Kiley, Karen Wynn, and Paul Bloom. "Social evaluation by preverbal infants." Nature 450.7169 (2007): 557-559.

[01:03:51] We're all grownup babies; Book: The Scientist in the Crib: What Early Learning Tells Us About the Mind, by Alison Gopnik.

[01:14:40] Books by Barbara Ehrenreich: Natural Causes, Nickel and Dimed: On (Not) Getting By in America, 

 and Bright-Sided: How Positive Thinking Is Undermining America.

[01:18:50] Cooperation because of self-domestication; Book: The Goodness Paradox: The Strange Relationship Between Virtue and Violence in Human Evolution; Study: Hare, Brian, Victoria Wobber, and Richard Wrangham. "The self-domestication hypothesis: evolution of bonobo psychology is due to selection against aggression." Animal Behaviour 83.3 (2012): 573-585.

[01:19:07] Books: Survival of the Friendliest: Understanding Our Origins and Rediscovering Our Common Humanity, by Brian Hare and Vanessa Woods; Dognition assessment and analysis.

[01:20:55] Bonobos exhibit delayed development of social behavior; Study: Wobber, Victoria, Richard Wrangham, and Brian Hare. "Bonobos exhibit delayed development of social behavior and cognition relative to chimpanzees." Current Biology 20.3 (2010): 226-230.

[01:21:57] Bonobos prefer individuals who hinder over those that help; Study: Krupenye, Christopher, and Brian Hare. "Bonobos prefer individuals that hinder others over those that help." Current Biology 28.2 (2018): 280-286.

[01:27:22] You can contact Kristen at the University of Utah, Department of Anthropology.