UCL Discovery
UCL home » Library Services » Electronic resources » UCL Discovery

A dynamic framework for the study of optimal birth intervals reveals the importance of sibling competition and mortality risks

Thomas, MG; Shanley, DP; Houston, AI; McNamara, JM; Mace, R; Kirkwood, TB; (2015) A dynamic framework for the study of optimal birth intervals reveals the importance of sibling competition and mortality risks. J Evol Biol , 28 (4) pp. 885-895. 10.1111/jeb.12613. Green open access

[img]
Preview
PDF
Thomas et al - JEB - 2015-02-23.pdf
Available under License : See the attached licence file.

Download (338kB)

Abstract

Human reproductive patterns have been well studied, but the mechanisms by which physiology, ecology and existing kin interact to affect the life history need quantification. Here, we create a model to investigate how age-specific interbirth intervals adapt to environmental and intrinsic mortality, and how birth patterns can be shaped by competition and help between siblings. The model provides a flexible framework for studying the processes underlying human reproductive scheduling. We developed a state-based optimality model to determine age-dependent and family-dependent sets of reproductive strategies, including the state of the mother and her offspring. We parameterized the model with realistic mortality curves derived from five human populations. Overall, optimal birth intervals increase until the age of 30 after which they remain relatively constant until the end of the reproductive lifespan. Offspring helping each other does not have much effect on birth intervals. Increasing infant and senescent mortality in different populations decreases interbirth intervals. We show that sibling competition and infant mortality interact to lengthen interbirth intervals. In lower-mortality populations, intense sibling competition pushes births further apart. Varying the adult risk of mortality alone has no effect on birth intervals between populations; competition between offspring drives the differences in birth intervals only when infant mortality is low. These results are relevant to understanding the demographic transition, because our model predicts that sibling competition becomes an important determinant of optimal interbirth intervals only when mortality is low, as in post-transition societies. We do not predict that these effects alone can select for menopause.

Type: Article
Title: A dynamic framework for the study of optimal birth intervals reveals the importance of sibling competition and mortality risks
Open access status: An open access version is available from UCL Discovery
DOI: 10.1111/jeb.12613
Publisher version: http://dx.doi.org/10.1111/jeb.12613
Additional information: Copyright © 1999-2015 John Wiley & Sons, Inc. All Rights Reserved.
Keywords: Humans, interbirth intervals, life history evolution, sibling competition, state-dependent optimality modelling.
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL SLASH
UCL > Provost and Vice Provost Offices > UCL SLASH > Faculty of S&HS
UCL > Provost and Vice Provost Offices > UCL SLASH > Faculty of S&HS > Dept of Anthropology
URI: https://discovery.ucl.ac.uk/id/eprint/1462822
Downloads since deposit
65Downloads
Download activity - last month
Download activity - last 12 months
Downloads by country - last 12 months

Archive Staff Only

View Item View Item