What Determines the Life Span of a Species?

Diverging in the initial assumptions, both mechanistic and evolutionary theories of aging suggest a positive correlation of indicators of life expectancy of animal species with body size and a negative correlation with fertility and metabolic rate. Such dependence is obviously traced within large taxa; however, when analyzing on a smaller scale (at the level of orders and families), ecological specialization of species can make a significant contribution to the variability of the corresponding indexes. In given work, correlative relationships between median and maximum life expectancy, on one hand, and the average values of body weight, fertility, muscle strength, the values of standard and maximum metabolic rates, locomotor activity, and emotionality in the open field test, on the other hand, are analyzed in eight species of Cricetidae family. The correlations with life expectancy were significant for all indicators except body weight. For locomotor activity, the correlation with life expectancy was positive; for other indicators, it was negative. The paper discusses possible reasons for differences in the strength of correlative relationships of the analyzed indexes with the maximum and median life expectancy from the point of view of mechanistic and evolutionary approaches to the analysis of the causes and mechanisms of aging.