The operation of metabolism determines species longevity, and in short-lived species this link tends to be highly variable in response to circumstances: exercise, diet, and consequences such as amounts and types of muscle and fat tissue. Longer lived species such as our own are, if anything, remarkable for the comparative lack of variation in life span across large differences in diet and the configuration of muscle and fat in our bodies. As researchers continue to map the interaction of metabolism and aging in laboratory mice, one interesting theme that has emerged is the importance of brown adipose tissue. In the open access paper noted here, the authors report that increasing the proportion of fat tissue that is brown rather than white can produce a 10-15% increase in mouse life span. They suggest this is mediated by SIRT3 activity and downstream effects on mitochondrial function.
The results here might be compared with a very intriguing study published last year in which researchers described what happens to metabolism and fat tissue in mice if their sense of smell is disabled. That resulted in healthier, metabolically superior mice characterized by a greater proportion of brown fat tissue. It built upon a
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