When does aging really shift into overdrive? A new study suggests it may be sooner than you think.

Scientists at the Chinese Academy of Sciences studied proteins in tissue taken from about 70 people ages 14 to 68, according to the study published July 25 in the journal Cell.

These proteins give scientists a window of when the aging process may begin on a cellular level, said Dr. Thomas Blackwell, associate dean for graduate medical education and professor of medicine at the University of Texas Medical Branch.