Figure 1.
Proportions of males exhibiting Parental or Nonparental behavior. Approximately fifty percent of adult, virgin, male C57Bl/6 mice exhibited parental behavior towards an unfamiliar infant. The propensity to express parental behavior was not altered by prior treatment with progesterone either 5 days ( χ2 test, p = 0.76) after removal of the hormone capsule. Data are presented as percentage of each group; numbers inside each bar are the numbers of individuals exhibiting each type of behavior.