article investigating some of the latest research on why humans have a finite lifespan.
"Death is the one certainty in life – a pioneering analysis of blood from one of the world's oldest and healthiest women has given clues to why it happens."
"Hendrikje van Andel-Schipper was at one point the oldest woman in the world. She was also remarkable for her health, with crystal-clear cognition until she was close to death, and a blood circulatory system free of disease. When she died in 2005, she bequeathed her body to science, with the full support of her living relatives that any outcomes of scientific analysis – as well as her name – be made public."
"Researchers have now examined her blood and other tissues to see how they were affected by age."
"What they found suggests that our lifespan might ultimately be limited by the capacity for stem cells to keep replenishing tissues day in day out. Once the stem cells reach a state of exhaustion they steadily diminish the body's capacity to keep regenerating vital tissues and cells, such as blood."
"In van Andel-Schipper's case, in the twilight of her life, about two-thirds of the white blood cells remaining in her body at death originated from just two stem cells, implying that most or all of the blood stem cells she started life with had already burned out and died."