Researchers at the Wellcome Sanger Institute published a study in the journal Nature that reveals a new theory behind aging. It is well understood that as we age, our cells change. These changes are called “somatic mutations.” What is not understood is “how such gradual accumulation of molecular damage could translate into the abrupt deterioration in how our organs function after the age of 70 years.” The researchers at the Wellcome Sanger Institute discovered that “production of blood cells in adults aged under 65 came from 20,000 to 200,000 stem cells, each of which contributed in roughly equal amounts. In contrast, blood production in individuals aged over 70 was very unequal.” This finding suggests that “age-associated changes in blood production come from somatic mutations causing ‘selfish’ stem cells to dominate the bone marrow in the elderly.” 

​​https://www.sanger.ac.uk/news_item/cellular-secrets-of-ageing-unlocked-by-researchers/