Separating the Bruce and Trivers‐Willard effects in theory and in human data

Separating the Bruce and Trivers‐Willard effects in theory and in human data INTRODUCTIONTheories of reproductive suppression posit that natural selection conserved mechanisms that reduce fertility when offspring would otherwise fail to thrive (Beehner & Lu, ; Haig, ; Wasser & Barash, ). This paper focuses on two mechanisms, the Bruce () and Trivers and Willard () Effects, thought to implement reproductive suppression in several species, including humans. Although the lines of literature describing these mechanisms rarely acknowledge each other, they have much in common. Both, for example, assume that pregnant women vary in their capacity to invest in children and that children vary in their need for maternal investment to thrive in prevailing environments. Both mechanisms also assume that low‐resource mothers with high‐need children will have relatively few grandchildren because their children will more frequently die before reproductive age than will the children of other mothers. These shared assumptions lead to the inference that natural selection would conserve mutations that spontaneously abort gestations in which the needs of the prospective child would otherwise exceed the resources of the prospective mother.The arguments embedded in these two lines of literature also have important differences. We describe these differences and explore historic data to determine which argument better describes temporal variation in an important http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png American Journal of Human Biology Wiley

Separating the Bruce and Trivers‐Willard effects in theory and in human data

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Publisher
Wiley Subscription Services, Inc., A Wiley Company
Copyright
© 2018 Wiley Periodicals, Inc.
ISSN
1042-0533
eISSN
1520-6300
D.O.I.
10.1002/ajhb.23074
Publisher site
See Article on Publisher Site

Abstract

INTRODUCTIONTheories of reproductive suppression posit that natural selection conserved mechanisms that reduce fertility when offspring would otherwise fail to thrive (Beehner & Lu, ; Haig, ; Wasser & Barash, ). This paper focuses on two mechanisms, the Bruce () and Trivers and Willard () Effects, thought to implement reproductive suppression in several species, including humans. Although the lines of literature describing these mechanisms rarely acknowledge each other, they have much in common. Both, for example, assume that pregnant women vary in their capacity to invest in children and that children vary in their need for maternal investment to thrive in prevailing environments. Both mechanisms also assume that low‐resource mothers with high‐need children will have relatively few grandchildren because their children will more frequently die before reproductive age than will the children of other mothers. These shared assumptions lead to the inference that natural selection would conserve mutations that spontaneously abort gestations in which the needs of the prospective child would otherwise exceed the resources of the prospective mother.The arguments embedded in these two lines of literature also have important differences. We describe these differences and explore historic data to determine which argument better describes temporal variation in an important

Journal

American Journal of Human BiologyWiley

Published: Jan 1, 2018

References

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