Hayflick Limit
This new year, researchers concluded that 2/3 of the difference in cancer risk between different parts of the body can be attributed to the number of stem cell divisions those parts undergo. More cell divisions reflect a higher risk as errors that occur naturally during the DNA replication process can contribute to the development of cancer. In other words, the same genetic mutability that enables evolution also ensures that many people will be afflicted by a terrible disease. On Pharyngula, PZ Myers suggests this is one reason our cells naturally get old and stop dividing: because if they…