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Updated: May 3, 2026

Determination of Self- and Inter-incompatibility Relationships in Apricot Combining Hand-Pollination, Microscopy and Genetic Analyses
Published on: June 16, 2020
Interbirth intervals: Intrafamilial, intragenomic and intrasomatic conflict
1Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA.
Background And Objectives:
Interbirth intervals (IBIs) mediate a trade-off between child number and child survival. Life history theory predicts that the evolutionarily optimal IBI differs for different individuals whose fitness is affected by how closely a mother spaces her children. The objective of the article is to clarify these conflicts and explore their implications for public health.
Methodology:
Simple models of inclusive fitness and kin conflict address the evolution of human birth-spacing.
Results:
Genes of infants generally favor longer intervals than genes of mothers, and infant genes of paternal origin generally favor longer IBIs than genes of maternal origin.
Conclusions And Implications:
The colonization of maternal bodies by offspring cells (fetal microchimerism) raises the possibility that cells of older offspring could extend IBIs by interfering with the implantation of subsequent embryos.
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