Table 2. Kinship and face distance.

Statistics obtained from general linear mixed models (proc GLIMMIX, SAS Studio) performed to study the relationships between face distances and a set of explanatory variables, including kinship, in (A) all adult female-female pairs of pictures, pairs aged less than 2 years apart, and pairs aged more than 2 years apart; and in (B) all juvenile female-female pairs, pairs aged less than a year apart, and pairs aged more than a year apart.

A	Explanatory variables	Estimate	F	P
All pairs (N = 6992 pairs, 45 females)	Kinship*		18.18	<0.0001
	MHS	0.51
	NK	1.21
	Age difference	0.04	3.07	0.080
	Kinship × Age difference†		9.13	0.0001
	Age × MHS	−0.08
	Age × NK	−0.11
Females ≤ 2 years (N = 2421 pairs, 43 females)	Kinship*		16.48	<0.0001
	MHS	0.79
	NK	1.43
	Age difference	−0.17	4.86	0.017
Females > 2 years (N = 4571 pairs, 44 females)	Kinship*		2.96	0.052
	MHS	−0.37
	NK	0.27
	Age difference	−0.02	0.97	0.32
B	Explanatory variables	Estimate	F	P
All pairs (N = 1589 pairs, 16 females)	Kinship*		12.04	<0.0001
	MHS	−2.97
	NK	2.66
	Age difference	−0.28	18.40	<0.0001
	Kinship × Age difference†		31.93	<0.0001
	Age × MHS	7.78
	Age × NK	−1.49
Juveniles ≤ 1 year (N = 805 pairs, 16 females)	Kinship*		3.85	0.022
	MHS	2.42
	NK	1.66
	Age difference	−0.59	2.08	0.15
Juveniles > 1 year (N = 784 pairs, 13 females)	Kinship*		0.92	0.40
	MHS	2.97
	NK	0.88
	Age difference	−2.62	39.97	<0.0001

*Class reference: PHS.

†Class reference: Age × PHS.