10.5061/DRYAD.Q3R3K
Thomas, Matthew G.
University College London
Shanley, Daryl P.
Newcastle University
Houston, Alasdair I.
University of Bristol
McNamara, John M.
School of Mathematics; University Walk; Bristol UK
Mace, Ruth
University College London
Kirkwood, Tom B. L.
Newcastle University
Data from: A dynamic framework for the study of optimal birth intervals
reveals the importance of sibling competition and mortality risks
Dryad
dataset
2015
Interbirth intervals
sibling competition
Life History Evolution
Humans
State-dependent optimality modelling
2015-03-04T19:44:52Z
2015-03-04T19:44:52Z
en
https://doi.org/10.1111/jeb.12613
https://doi.org/10.5281/zenodo.15663
https://doi.org/10.5281/zenodo.15737
19197315 bytes
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CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
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.
Model source codeThis link is to a page providing access to code hosted on
Zenodo. The Zenodo page also includes a link to source code hosted on
GitHub.Model data filesData files from all experiments used to generate
figures in the paperibi model output.zipAnalysis codeThis link is to a
page providing access to code hosted on Zenodo. The Zenodo page also
includes a link to analysis code hosted on GitHub.