Mitochondria are the power plants of the cell and are important in aging: damage to their DNA contributes to degenerative aging through a complex process, and differences in mitochondrial resistance to damage is thought to go a long way towards determining variation in species life span. So it should not be surprising to see associations between different mitochondrial DNA haplogroups and human longevity, as is the case here: "Human longevity is an interesting and complicated subject, with many associated variations, geographic and genetic, including some known mitochondrial variations. The population of the Bama County of Guangxi Province of China is well known for its longevity and serves as a good model for studying a potential molecular mechanism. In this study, a full sequence analysis of mitochondrial DNA (mtDNA) has been done in ten Bama centenarians using direct sequencing. [Mitochondrial DNA was also] analyzed for a total of 313 Bama individuals with ages between 10 and 110 years. The results showed that there were seven mitochondrial variations [and] four haplogroups [in] 10 Bama centenarians. In the D-loop region of mtDNA, the mt146T occurred at a significantly lower frequency in those is the older age group (90-110 years) than in the middle (80-89 years) and in the younger (10-79 years) groups. The mt146T also had lower systolic blood pressure and serum markers such as total cholesterol, triglyceride and low density lipoprotein than did mt146C in the older age group. ... These results suggest that the mt146T/C polymorphisms in Guangxi Bama individuals may partly account for the Bama longevity."