Figure 4: Paternal parental behaviour in the separation paradigm under various conditions.

(a–h) A schematic representation of the care behaviour test in a mouse pair housed in the same cage (c,f) and isolated from pups in (b) and away from the home nursing cages (a). During the 10-min separation, the parental female was housed either in an open-top box (c) or in a close box (f). The male was then reunited with the pups (d,g), and his subsequent retrieval behaviour (one trial per male) was observed (e,h). (i) Percentage of sires with retrieval responses. The first two columns show responses when the dam was placed in the open-top (c) or sealed box (f). Columns 3–5 show the retrieval behaviour by sires with deafness (with wax ear plugs), anosmia (with 5% ZnSO₄ solution poured into both nostrils) or both. N=12 sires each, Fisher’s test, two-tailed, *P<0.05. (j) Acoustic and olfactory cues independently induced paternal parental behaviour. USVs were recorded for 10 min from a dam in a new cage with a sire after his removal from a home cage or from virgin females; USVs from the maternal mate (columns 1 and 3) were then played back in a soundproof chamber to the father of the same couple in a new cage (column 1) or in the cage that had previously housed the dam (excreta; column 3). Sires were exposed either to USVs from virgins in a new cage (column 2) or only to the virgins’ excreta (column 5), as above. The sires were then scored for retrieval behaviour when they were returned to their old home cages with pups. N=9–15 subjects, Fisher’s test, two-tailed, *P<0.05.