Dr. Jonas Frisen, a biologist at the Karolinska Institute in Stockholm, Sweden, has found a method to determine the age of the cells in our bodies. After a number of tests and experiments, he has found that most cells get constantly renewed, so regardless of your actual age, your body may be only 7-10 years old.
Dr. Frisen also discovered why human bodies display their birth age instead of the physical age of their cells. According to Frisen, there are some types of cells that never undergo a renewal. Among them are a large part of the cells found on the cerebral cortex.
The dating method developed by Frisen is based on the presence in the atmosphere of radioactive carbon 14 that is a result of nuclear weapon testing carried out up to 1963. Carbon 14 becomes part of the human DNA cells which are never renewed, so it can be used to determine the actual age of the cells.