The Selfish Grandma Gene: The Roles of the X-Chromosome and Paternity Uncertainty in the Evolution of Grandmothering Behavior and Longevity

Table 3

The circumstances under which an X-linked gene coding for favoritism of granddaughters would accumulate in a population using Rice et al. [8] model, given five rates of paternal discrepancy: 0% (as reported in Rice et al. [8], and consistent with Skorecki et al. [24]); 1.3% (estimate based on Simmons et al. [25] and Sykes and Irven [26]); 3.7% (estimate based on Bellis et al. [27]); 10% (popular unfounded figure included here to show range of possibility).

Rate of paternal discrepancy →	0%	1.30%	3.70%	10%
When X-linked mutation helping granddaughters at	Its frequency would increase provided the expense to grandsons is no more than
expense of grandsons is expressed in:	(values below) times the benefit to granddaughters
All grandparents (dominant expression)	2	1.993457	1.98167	1.947368
All grandparents (additive expression)	1.5	1.331876	1.329235	1.321429
Grandmothers only (dom or add expression)	3	2.97400	2.9280	2.8000
Paternal grandmothers only (dom or add expression)	No limit	No limit	No limit	No limit