Grandmothering drives the evolution of longevity in a probabilistic model

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

Date Published: 2014-07-21

DOI: 10.1016/j.jtbi.2014.03.011

Sponsors: United States National Science Foundation (NSF)

Platforms: Python

Model Documentation: Other Narrative

Model Code URLs: Model code not found

Abstract

We present a mathematical model based on the Grandmother Hypothesis to simulate how human postmenopausal longevity could have evolved as ancestral grandmothers began to assist the reproductive success of younger females by provisioning grandchildren. Grandmothers' help would allow mothers to give birth to subsequent offspring sooner without risking the survival of existing offspring. Our model is an agent-based model (ABM), in which the population evolves according to probabilistic rules governing interactions among individuals. The model is formulated according to the Gillespie algorithm of determining the times to next events. Grandmother effects drive the population from an equilibrium representing a great-ape-like average adult lifespan in the lower twenties to a new equilibrium with a human-like average adult lifespan in the lower forties. The stochasticity of the ABM allows the possible coexistence of two locally-stable equilibria, corresponding to great-ape-like and human-like lifespans. Populations with grandmothering that escape the ancestral condition then shift to human-like lifespan, but the transition takes longer than previous models (Kim et al., 2012). Our simulations are consistent with the possibility that distinctive longevity is a feature of genus Homo that long antedated the appearance of our species. (C) 2014 Elsevier Ltd. All rights reserved.

Tags

Agent-based modeling Human evolution Human longevity Life history Sexual conflict