One of the major changes in signaling in our aging bodies is thanks to a process which will be a recurring character in this book, known as inflammation. Inflammation is our body’s first line of defense against infection and injury, which often results in the site of the problem swelling up. The inflammatory response is the molecular equivalent of

The Amish community in Berne provided an ideal test case, and Shapiro applied to the National Institutes of Health for funding to perform a study. Her grant application was rejected: the NIH didn’t think 100 subjects would be enough to discern a statistically robust effect. How wrong they were.

If a mitochondrion slightly fumbles the incredibly complex chemistry behind producing power safely, it can create a “free radical”—a highly reactive chemical which can go on to cause chaos in the cell, damaging proteins, DNA, and any other critical molecules it comes across. Three of the most biologically important free radicals are OH, NO and

One piece of news that very slightly offsets the raw deal for men is that, curiously, though women live longer, they tend to do so with worse health on average. There is still some debate about the size and even the existence of this phenomenon, but perhaps the most compelling data come from centenarians: one study found that women over the age of

Understanding aging could have enormous implications because it is by far the world’s leading cause of death and suffering. While that might sound counterintuitive, looking at aging as a biological process makes the logic inescapable. As we age, our bodies accrue a familiar array of changes—from the superficial, like gray hair, wrinkles and

Senescent cells do that by secreting inflammatory molecules which alert the immune system to their presence, asking to be removed.

We’ve seen that a reduction in autophagy—the “self-eating” process of cellular recycling which clears up broken proteins, damaged mitochondria and more—is likely to be central to the aging process.

Memory T cells can stick around for decades and, if their old foe returns, they’re the most highly proliferative cells in the body: a handful of memory cells can expand to form a clone army of millions. This puts the cells themselves under incredible strain—DNA damage and shortened telomeres from dividing many times can lead to cellular damage and

Thus, the second idea in the evolution of aging is “antagonistic pleiotropy”—the idea of genes which have multiple effects allowing them to conspire to aid reproduction in early life, but go on to cause problems as the animal gets older.