My mother lived past the century mark. In fact, she died one week past her 101st birthday. But she didn’t end up as one of those mentally and physically robust centenarians that researchers love to study. By the time she died, my mom was frail and nearly bedridden. Dementia twisted her mind, osteoarthritis crushed her right knee, and then her heart gave out.
Even with health issues, her attitude stayed strong. She loved to dance, and she was a badass in the gym, well into her nineties. No matter what happened to her body — she also survived two bouts of breast cancer — her young outlook kept my mother smiling, even when she was weak and in hospice.
Every organism ages — even bacteria. Why aging happens, however, is still one of the biggest mysteries in biology. Researchers have come up with many theories about why we age, but here’s the most common explanation: Damage starts in our cells from early life exposure to everything from environmental toxins to pathogens, poor nutrition and even lifestyle choices like smoking. As decades pass, impaired cells weaken tissues and organs, which turn sparks decline across the body.