The relationship of genotype, sex, body weight, and growth parameters to lifespan in inbred and hybrid mice.

Data from nine inbred and six hybrid mouse strains of both sexes were used in a correlational analysis to examine the relationships between lifespan and several growth parameters, including body weight at weaning, at 6 weeks after weaning, and at 1 year, and estimates of growth rate, food consumption, and feeding efficiency during early life. The analysis revealed strong relationships of genotype to all variables. Hybridization was associated with longer lifespan, but sex was not related to lifespan. Several growth parameters were significantly related to lifespan, but the directions of the correlations were sex-dependent. Several body weight and growth parameters were positively correlated to lifespan in males, while negatively correlated to lifespan in females. Genotype accounted for most of the variance in these relationships with the exception of hybrid males, where the correlation between growth rate and lifespan was attributable largely to environmental factors. In demonstrating significant correlations between lifespan and constitutional variables within a species, the results supported a morphogenetically based hypothesis of lifespan inheritance; however, the sex differential in the direction of the relationship between growth and lifespan further demonstrated the difficulty of making predictions deduced from the hypothesis.