Why Grandmothers May Hold The Key To Human Evolution | Kristen Hawkes | The Grandmother Hypothesis


♦ The Evolution Of Parenting | Goats & Soda | NPR

The real secret to humans’ success? It might have a lot to do with how we raised our kids. • Read or listen to: “Why Grandmothers May Hold The Key To Human Evolution” at https://www.npr.org/sections/goatsandsoda/2018/06/07/617097908/why-grandmothers-may-hold-the-key-to-human-evolution

♦ CARTA: Childrearing in Human Evolution — Kristen Hawkes: Grandmothers and the Extended Family

Conjugal families are often assumed to be building blocks of human societies and the primary site of childrearing in traditional communities. Alternatively, Kristen Hawkes (Univ of Utah) contends that the Grandmother Hypothesis draws attention to other relationships likely fundamental in the evolution of our lineage. Persistent ties that crosscut conjugal families are implied by our cooperative childcare, distinctive prosociality, and extraordinary operational sex ratios. These high operational sex ratios also affect the way men negotiate with other men, which in turn affects the economics of childrearing. Recorded on 02/21/2014. Series: “CARTA – Center for Academic Research and Training in Anthropogeny”

♦ Kristen Hawkes on the Grandmother Hypothesis of evolution

Consider the hypothesis that increased longevity is a key to the evolution of human life history and other features that distinguish us from the great apes. The Grandmother Hypothesis implies novel challenges for ancestral mothers and infants that favored the evolution of the distinctly human preferences for joint attention that underpin our cultural lives. Anthropologist Kristen Hawkes explores the connections that link our grandmothering life history to men’s status competition, which propels so much in human affairs, including the economic productivity that is a hallmark of our lineage.

♦ Grandmothers and Human Evolution | Kristen Hawkes

Grandmothers contribute to our big brains, obsession with reputations, and the cultural construction of our daily lives. In this lecture, Leakey Foundation grantee Kristen Hawkes shares her research that shows that grandmothers are not only vital to child rearing and cooperation, but also to forming interdependent economies. Hawkes uses insights into our ancestors’ behavior revealed by her work with modern hunter-gatherer groups, such as the Hadza people of Tanzania who live primarily by hunting and harvesting wild foods. “Grandmothers and Human Evolution” was presented at the Houston Museum of Natural Science on November 6, 2019, as part of The Leakey Foundation’s Speaker Series program in partnership with the Houston Museum of Natural Science.

♦ CARTA 10th Anniversary Symposium: Hawkes, Crittenden, Churchland

1:42 – Kristen Hawkes – Hunter-Gatherers/Life History & Reproduction

16:45 – Alyssa Crittenden – Parenting and Child Development

32:35 – Patricia Churchland – Morality & Cooperation

CARTA celebrates its 10th anniversary with a whirlwind tour of anthropogeny, the study of the origin of humans, by addressing these questions across multiple disciplines: What do we know for certain? What do we think we know? What do we need to know? How do we proceed? This program: Kristen Hawkes, Alyssa Crittenden, Patricia Churchland. Recorded on 3/23/2019. Series: “CARTA – Center for Academic Research and Training in Anthropogeny” [5/2019] [Show ID: 34694]

♦ Exploring The Human-Ape Paradox – Alyssa Crittenden, Kristen Hawkes, Margaret Schoeninger

(01:32 – Cooperative Breeding,

14:18 – Ancient Grandmothers, Ancient Savannas,

30:15 – Nutrition and Diet)

Each species of our primate cousins is unique as it represents the outcome of independent evolution. Yet, humans appear to be a remarkable outlier as we have numerous characteristics so far un-described in any other primate. Why should this be? This symposium will address several important distinctly human “biologically enculturated” characteristics, both in relation to each other and in contrast to our evolutionary cousins, and will also help to organize how and in what sequence distinctly human physical, mental, social, and cultural features evolved. [12/2020] [Show ID: 36199]


♦ The Grandmother Hypothesis and Human Evolution

By Kristen Hawkes, James F. O’Connell, Nicholas G. Blurton Jones, Helen Alvarez, Eric L. Charnov

Cronk, L., Chagnon, N., & Irons, W. (Eds.). (2000). Adaptation and Human Behavior: An Anthropological Perspective (1st ed.). Routledge. https://doi.org/10.4324/9781351329200



This chapter summarizes the grandmother hypothesis and the life history patterns it may explain, note that it joins other challenges to the hunting hypothesis. It discusses alternative predictions about human evolution based on the idea that mother-child food sharing and the grandmothering it permits are among their most important behavioral characteristics. The grandmother hypothesis suggests a different model of human evolution than the conventional one that makes men’s big game hunting and provisioning of mates and offspring the keystone human adaptation. The grandmother hypothesis implies that childbearing women produces babies faster than otherwise expected because of grandmothers’ contribution to that production. The grandmother hypothesis should stimulate increased attention to the activities of older women and explicit examination of the spatial proximity of mothers and daughters. The grandmother hypothesis provides a rationale for the modeling needed to identify critical tests.

♦ Grandmothers and human pair bonds

James E. Coxworth, Peter S. Kim, John S. McQueen, Kristen Hawkes

Proceedings of the National Academy of Sciences Sep 2015, 112 (38) 11806-11811; DOI:10.1073/pnas.1599993112



Pair bonds are universal in human societies and distinguish us from our closest living relatives. They characteristically involve men’s proprietary claims over women—mate guarding—which in animals generally is both predicted and observed to be more frequent when sex ratios in the fertile ages are male-biased. A marked male bias in the fertile ages evolved in our lineage as longevity increased without an extension of female fertility. We compare the sex-ratio shift in simulations of the grandmother hypothesis to demographic data from chimpanzees and human hunter–gatherers then connect the expanded proportions of older men to benefits for mate guarding, the evolution of pair bonds, and the long recognized importance of male alliances in human social life.


The evolution of distinctively human life history and social organization is generally attributed to paternal provisioning based on pair bonds. Here we develop an alternative argument that connects the evolution of human pair bonds to the male-biased mating sex ratios that accompanied the evolution of human life history. We simulate an agent-based model of the grandmother hypothesis, compare simulated sex ratios to data on great apes and human hunter–gatherers, and note associations between a preponderance of males and mate guarding across taxa. Then we explore a recent model that highlights the importance of mating sex ratios for differences between birds and mammals and conclude that lessons for human evolution cannot ignore mammalian reproductive constraints. In contradiction to our claim that male-biased sex ratios are characteristically human, female-biased ratios are reported in some populations. We consider the likelihood that fertile men are undercounted and conclude that the mate-guarding hypothesis for human pair bonds gains strength from explicit links with our grandmothering life history.

♦ Grandmothers and the evolution of human longevity: a review of findings and future directions

Kristen Hawkes, James E Coxworth

Hawkes K, Coxworth JE. Grandmothers and the evolution of human longevity: a review of findings and future directions. Evol Anthropol. 2013 Nov-Dec;22(6):294-302. doi: 10.1002/evan.21382. PMID: 24347503.

Kristen Hawkes’s hunter‐gatherer ethnography drew her attention to unexpected sex and age differences in foraging strategies. including the crucial productivity of grandmothers, which prompted further comparisons of human and chimpanzee life histories.

James E. Coxworth’s central interest is the application of evolutionary tools to describe and explain male competitive strategies, with particular emphasis on human evolution. This interest has led to statistical and modeling contributions and to projects investigating human life‐history evolution.


Women and female great apes both continue giving birth into their forties, but not beyond. However humans live much longer than other apes do. Even in hunting and gathering societies, where the mortality rate is high, adult life spans average twice those of chimpanzees, which become decrepit during their fertile years and rarely survive them.  Since women usually remain healthy through and beyond childbearing age, human communities include substantial proportions of economically productive postmenopausal women. A grandmother hypothesis may explain why greater longevity evolved in our lineage while female fertility still ends at ancestral ages. This hypothesis has implications for the evolution of a wide array of human features. Here we review some history of the hypothesis, recent findings, and questions for ongoing research.


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