ScienCentral is running an article on recent work on accelerated aging in mice: "We altered two bases in the gene and made it defective so that it can now function in the copying of the DNA but can no longer function as a spell-checker. As a result of that, the mitochondrial DNA accumulates mutations. ... The researchers concluded that this increased number of mutations (3 to 8 times as many as in normal mice) was the reason for the increased rate of cell-suicide that they observed in the fast-aging animals. Because of those mutations, cells that make up many parts of the body - from hair to bone to muscle - prematurely committed suicide. ... Once they're lost, the tissues which they support will no longer be able to regenerate. So the loss of stem cells is probably a critical feature of accelerated aging."