A number of hypotheses have been proposed to explain how males might avoid harming their own offspring and, instead, give paternal care (reviewed by Elwood, 1985). These are of two main types. One type, previously referred to as "recognition hypotheses" (Elwood, 1985), proposes that the male uses some aspect of the situation in which the infants are encountered to make an 'on the spot' decision. The second type proposes that males are brought into a 'non-infanticidal state' or even a "parental state" at a time when their own young are likely to be born.