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Maternal investment, life histories, and the evolution of brain structure in primates

Powell, Lauren E; Barton, Robert A; Street, Sally E.

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Authors

Lauren E Powell



Abstract

Life history is a robust correlate of relative brain size: larger-brained mammals and birds have slower life histories and longer lifespans than smaller-brained species. The cognitive buffer hypothesis (CBH) proposes an adaptive explanation for this relationship: large brains may permit greater behavioural flexibility and thereby buffer the animal from unpredictable environmental challenges, allowing for reduced mortality and increased lifespan. By contrast, the developmental costs hypothesis (DCH) suggests that life-history correlates of brain size reflect the extension of maturational processes needed to accommodate the evolution of large brains, predicting correlations with pre-adult life-history phases. Here, we test novel predictions of the hypotheses in primates applied to the neocortex and cerebellum, two major brain structures with distinct developmental trajectories. While neocortical growth is allocated primarily to pre-natal development, the cerebellum exhibits relatively substantial post-natal growth. Consistent with the DCH, neocortical expansion is related primarily to extended gestation while cerebellar expansion to extended post-natal development, particularly the juvenile period. Contrary to the CBH, adult lifespan explains relatively little variance in the whole brain or neocortex volume once pre-adult life-history phases are accounted for. Only the cerebellum shows a relationship with lifespan after accounting for developmental periods. Our results substantiate and elaborate on the role of maternal investment and offspring development in brain evolution, suggest that brain components can evolve partly independently through modifications of distinct developmental phases, and imply that environmental input during post-natal maturation may be particularly crucial for the development of cerebellar function. They also suggest that relatively extended post-natal maturation times provide a developmental mechanism for the marked expansion of the cerebellum in the apes.

Journal Article Type Article
Acceptance Date Aug 15, 2019
Online Publication Date Sep 18, 2019
Publication Date Sep 18, 2019
Deposit Date Aug 29, 2019
Publicly Available Date Aug 29, 2019
Journal Proceedings of the Royal Society B: Biological Sciences
Print ISSN 0962-8452
Electronic ISSN 1471-2954
Publisher The Royal Society
Peer Reviewed Peer Reviewed
Volume 286
Issue 1911
Article Number 20191608
DOI https://doi.org/10.1098/rspb.2019.1608
Public URL https://durham-repository.worktribe.com/output/1289411

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