A1 Journal article – refereed
Limited support for the X-linked grandmother hypothesis in pre-industrial Finland

List of Authors: Chapman Simon N., Pettay Jenni E., Lummaa Virpi, Lahdenperä Mirkka
Publisher: Royal Society Publishing
Publication year: 2018
Journal: Biology Letters
Journal name in source: Biology Letters
Volume number: 14
Issue number: 1
Number of pages: 4
ISSN: 1744-9561
eISSN: 1744-957X


The level of kin help often depends on the degree of relatedness between a helper and the helped. In humans, grandmother help is known to increase the survival of grandchildren, though this benefit can differ between maternal grandmothers (MGMs) and paternal grandmothers (PGMs) and between grandsons and granddaughters. The X-linked grandmother hypothesis posits that differential X-chromosome relatedness between grandmothers and their grandchildren is a leading driver of differential grandchild survival between grandmother lineages and grandchild sexes. We tested this hypothesis using time-event models on a large, multigenerational dataset from pre-industrial Finland. We found that the presence of an MGM increases grandson survival more than PGM presence, and that granddaughter survival is higher than that of grandsons in the presence of a PGM. However, there was no support for the key prediction that the presence of PGMs improves granddaughter survival more than that of MGMs, diminishing the overall support for the hypothesis. Our results call for alternative explanations for differences in the effects of maternal and paternal kin to grandchild survival in humans.

Last updated on 2019-21-08 at 20:38

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