Def: when the evolutionary interests of males and females diverge, often over reproduction (mating frequency, offspring investment); leads to arms races between sexes (toxic semen vs female resistance)
M/F imprinted genes for different parts of the embryo
In the two-mothers case, the embryo itself was properly organised, but it could not make a placenta with which to sustain itself. In the two-fathers case, the embryo grew a large and healthy placenta and most of the membranes that surround the foetus. But inside, where the embryo should be, there was a disorganised blob of cells with no discernible head. 3 These results led to an extraordinary conclusion. Paternal genes, inherited from the father, are responsible for making the placenta; maternal genes, inherited from the mother, are responsible for making the greater part of the embryo, especially its head and brain.
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if we are to believe that the placenta is an organ that the father’s genes do not trust the mother’s genes to make, then the cerebral cortex is an organ that the mother’s genes do not trust the father’s genes to make.
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Paternal imprinted for maternal behavior
- Missing maternal X (expressing paternal X) had better social and verbal skills → key female social behaviors may be paternally imprinted
paternal X chromosomes are found only in females. Therefore, behaviour that is characteristically required of females should be expressed only from paternal chromosomes. If they were also expressed from maternal X chromosomes, they might appear in males, or they might be overexpressed in females. It therefore makes sense that maternal behaviour should be paternally imprinted.
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The twenty-five girls missing the maternal chromosome were significantly better adjusted, with ‘superior verbal and higher-order executive function skills, which mediate social interactions’ than the fifty-five girls missing the paternal chromosome.
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