There are certain compounds in a person's spit that can reveal their age to within 5 years. No kidding. There are certain things we know about DNA. We know that DNA gets methylated (like ornaments on a Christmas tree). We also know that the methylation pattern on the DNA changes with age. So the hypothesis was whether looking at the methylation pattern of the DNA can reveal a person's age? And guess what... it does according to a recently published study. In this study published on…