Table 1.

Estimates of population genetic parameters

Population	n	S	θw	θml	D	N	TMRCA	Nm
African	16	23	6.93	5.78	0.66	23,833	3.88	4.81
			(2.98)	(2.19)			(0.88)
Non-African	19	2	0.57	0.62	−0.48	2,561	2.84	1.96
			(0.45)	(0.49)			(1.46)
Old World	35	25	6.07	4.41	0.78	18,184	4.75	–
			(2.24)	(1.34)			(1.09)

n is the number of sequences sampled. S is the number of polymorphic sites observed in the sample. θ_w is Watterson’s estimate of the population genetic parameter, 3Nu for an X-linked gene, where N is the effective population size and u is the mutation rate for the region, per generation (42, 43). θ_ml is the maximum likelihood estimate of the same parameter determined by using the genetree program. D indicates the departure of polymorphic site frequencies from those expected under neutrality and constant population size (34). The effective population size estimate, N, was obtained by dividing θ_ml by 3 and by 4.042 × 10⁻⁶ (the mutation rate estimate, see text), and by 20 (an assumed value for the number of years per generation that is necessary to convert units from years to generations). The estimated time to the most recent common ancestor (TMRCA) was determined by using the genetree program. The units are N generations and should be multiplied by N and 20 to convert to years. Nm, the estimate of the migration per generation among subpopulations, was also determined by using the genetree program. Nm could not be determined for the entire Old World sample because of the absence of any shared haplotypes between African and non-African samples. Standard deviations are in parentheses.