Rising levels of oxidative stress occur with aging. This term describes the presence of excessive numbers of oxidative molecules, reacting with surrounding molecular machinery to cause breakage and cellular dysfunction. It is significant enough in aging for the free radical theory of aging to have arisen some decades ago, postulating that oxidative damage was the cause of aging. Alas, matters are not that simple. Persistently raised levels of oxidative stress are a downstream consequence of deeper causes, such as mitochondrial dysfunction, chronic inflammation, cellular senescence, and the like. Further, oxidative molecules do in fact serve a necessary and useful role in healthy cellular metabolism. They act as signals to spur cellular maintenance, for example, and thus small or temporary increases in oxidative stress tend to be beneficial. This is one of the mechanisms by which exercise produces health benefits.
Naked mole rats are a strange species, an outlier among rodents. They are eusocial, like some insects. They live nine times longer than similarly sized rodent species, and show few signs of aging across most of that life span. They exhibit high levels of oxidative stress, but appear near completely immune