Biological clock found that can measure age of most human tissues

... in the Oct. 21 edition of Genome Biology , the findings could offer valuable insights into cancer and stem cell research. While earlier clocks have been linked to saliva, hormones and telomeres, the new research is the first to identify an internal ...

http://www.rdmag.com/news/2013/10/biological-clock-found-can-measure-age-most-human-tissues