We’ve all heard the phrase “live fast, die young.” If you make risky moves and act recklessly, you’re more likely to die prematurely. But, in biology, animals with a higher metabolic rate tend to die younger than those with a slow metabolism. But, there isn’t a clear-cut relationship between metabolism and lifespan. A more accurate saying might actually be “live cold, die old.”
While the metabolism link seems evident at first, it gets muddied. Some life-extending behaviors slow the metabolism. Eating fewer calories lowers the metabolism and can lead to weight loss and longer life. But exercising, which extends life, increases the metabolism. Metabolism rates are linked to body temperature. Researchers wondered if body temperature more than metabolism was the factor in predicting lifespan.
A new study aimed to separate the two factors. While a slow metabolism is usually associated with a low body temperature and a fast metabolism correlates to a high temperature, they did their best to reverse it.
Researchers exposed rats and hamsters to the highest temperatures they could live at. “We found that exposing the rodents to these conditions shortened their lifespans. Lower metabolism didn’t lengthen their lives, but higher temperatures shortened it,” said Prof. John Speakman from the Shenzhen Institute of Advanced Technology, a co-corresponding author of the study.
When they blew fans on the animals to keep them cool, it had no impact on their metabolisms. But it did lower their body temperatures and reversed the effect the heat had on their lifespan.
“We separated the effect of body temperature on lifespan from metabolic rate in two species of small rodents exposed to high temperatures. We are excited about the findings, particularly that using small fans to blow air over the animals reversed the effect of high ambient temperature on lifespan by decreasing body temperature without changing metabolic rate,” said Zhao Zhijun from Wenzhou Univ., who was the first and co-corresponding author of this study.
Animal studies don’t always correlate to human results. So a lot more steps need to be taken before we know how excited we should be over this research. It also ignores the critical question of quality of life. “Live cold, die old” might sound like great advice, but what temperature do we need to keep our bodies to benefit from it? And, living longer doesn’t always mean living healthier. Many of these studies on longevity fail to consider how healthy we’ll be. Living longer isn’t the only measurement of aging well. While we are excited to read about this discovery, we need more proof and information before we start making our homes uncomfortably chilly.