Correlations are pointers - they indicate where future research and development may best be directed. Here, researchers demonstrate a strong correlation between mammalian life span and various mitochondrial characteristics: "In animal cells, mitochondria are semiautonomous organelles [with] their own code and genome (mtDNA). The semiautonomy and restricted resources could result in occasional 'conflicts of interests' with other cellular components, in which mitochondria have greater chances to be 'the weakest link,' thus limiting longevity. ... (1) to what extent the mammalian maximum life span (MLS) is associated with mtDNA base composition? (2) Does mtDNA base composition correlate with another important mitochondria-associated variable - resting metabolic rate (RMR) - and whether they complement each other in determination of MLS? ... Analysis of 140 mammalian species revealed significant correlations ... To the authors' knowledge, it is the highest coefficient of MLS determination that has ever been reported for a comparable sample size. Taking into account substantial errors in estimation of MLS and RMR, it could mean that [this explains] most of the MLS biological variation. [This leads us to] mitochondria as a primary object for longevity-promoting interventions."