Fig. 1: Father companionship increased the defensive attack behavior of offspring.

a Experimental design. In the father companionship group, the sire lived with the dam and offspring from conception through weaning. In the control group, only the dam lived with offspring during this period. b The effect of father’s companionship on the latency of biting (two-way ANOVA, effects of father companionship: F _{(1, 68)} = 2.185, P = 0.144, η2 = 0.031; effect of sex: F _{(1, 68)} = 1.766, P = 0.188, η2 = 0.025; interaction effect: F _{(1, 68)} = 0.236, P = 0.629, η2 = 0.003). c Father’s companionship increased the frequency of biting (two-way ANOVA, effects of father companionship: F _{(1, 68)} = 4.370, P = 0.040, η2 = 0.060; effect of sex: F _{(1, 68)} = 0.493, P = 0.485, η2 = 0.007; interaction effect: F _{(1, 68)} = 1.238, P = 0.270, η2  = 0.018). (d) Father’s companionship increased the biting duration (two-way ANOVA, effects of father companionship: F _{(1, 68)} = 5.331, P = 0.024, η2 = 0.073; effect of sex: F _{(1, 68)}= 0.241, P = 0.625, η2 = 0.004; interaction effect: F _{(1, 68)} = 0.803, P = 0.374, η2 = 0.012). n = 17-19 per group. Values are shown as mean ± standard error. FC father companionship, PD pregnancy day, PND postnatal day. * P <0.05.