Right now the limit of how old we can get is between 110 and 120 years. Occasionally you have outliers who turn a bit older. But the limiting factors are:
- Our energy organelles, the mitochondria are disappearing as we age. Each of our body cells has hundreds of these energy packages. If only 50 are leftover, our body energy is dwindling. The brain, the heart and the skeletal muscles have thousands of mitochondria in every cell. If half of these disappear, we fall asleep on a chair (senescent people do that) and we have a shuffled gait. Our heart may start failing, so congestive heart failure may sets in.
- Our DNA is stable most of our lives because we have repair mechanisms in place. But the older we get, the more mutations occur, as the repair mechanism ages. This can cause cancer. But we may also lose bits and pieces of our DNA and various body deficiencies start occurring.
- Our telomeres, the caps on each of our chromosomes are getting shorter, the older we get. This is no problem when we are younger. But as we age, the stem cells that normally have the longest telomeres are also starting to have shorter telomeres. Now this affects cell replacement. If you don’t replace the cells that are lacking you get organ deficiencies and organ failures. Many old people die because of heart failure, bone marrow failure (no blood cells, no immune cells), kidney failure, liver failure and dementia (brain failure).
- Until we will be able to address my concerns expressed under point 1 to 3 we will have problems extending our life expectancy limits.