At 21 days of age, 144 female albino mice were individually isolated and reared on either 8%, 16% or 24% protein diets. Within each protein level, mice were exposed to the presence of an adult male, or to male odour, or were reared in isolation. Each female was examined daily for vaginal opening and signs of first oestrus. Body weight and food consumption measures confirmed that body growth was equal in each cell of the design and that mice on low protein diets were not compensating for a low protein diet by consuming more food.
The results showed that, although both dietary protein and the presence of males (or their odour) were significant factors in regulating sexual maturation, social factors contributed 47·3% and dietary protein levels 4·8% of the total variance. Accelerated sexual development was not accompanied by accelerated body growth. Thus, the hypothesis that puberty occurs at a critical body weight was not supported by these data. That social stimulation was more effective than protein intake may have relevance to the phenomenon of accelerated sexual maturation in human females.