[The formation of predatory aggressiveness in the ontogeny of rats]

In tests on outbred male rats the problem was studied of the existence of "sensitive periods" in the formation of rats predatory aggression. Breeding of small rats together with mice from the first till 60-th postnatal day considerably inhibits their muricidity in the adult age, what is manifest in tests of predatory aggressiveness till the 270-th day of rats life. Breeding of mice together with rats in the age of 1-20, 20-40, 40-60 and 20-60 postnatal days does not influence significantly their muricidity. Antiaggressive effect of breeding of mice with adult rats from the 150-th to the 210-th day is a short-term one, and breeding of mice with old rats in the age of 540-600 postnatal days does not significantly effect the muricidity.