Liver was selected for this analysis because as the central metabolic organ of the body it is a major target of oxidative DNA damage, a postulated cause of aging, and suffers from some prominent aging-related pathology [11].
"What's wrong with finding the cause of aging?" his father asked.
"There's nothing wrong with finding the cause of aging," Jef said.
This, Dr. Sinclair and his colleagues suggest, may be a fundamental cause of aging in mice and probably people, too.
"I thought I had discovered the cause of aging and was going to win the Nobel Prize," Ferrucci said, laughing.
"We are careful not to say this is the cause of aging, but based on everything we know it's not a bad hypothesis," he said.
The second problem was the immense difficulty of determining whether any seeming cause of aging was actually causal, or merely a correlative of some other, stealthier process.
Ronald Evans, a biologist at the Salk Institute, said the new report was provocative but did not prove the case that the relocation of sirtuin was a cause of aging.
Fibrosis is a common process characterized by excessive extracellular matrix (ECM) accumulation after inflammatory injury, which is also a crucial cause of aging.
This raises the question whether the ultimate cause of aging is more than a lack of adaptation, but an inherent fragility of complex evolutionary systems.
"They're really pinning down a cause of aging," says Matthew Longley, a biochemist at the National Institute of Environmental Health Sciences in Research Triangle Park, North Carolina.
