Thousands of years ago, birch pitch was used as chewing gum. Just one piece of this chewing gum from 5,700 years ago was found to hold enough DNA to determine what one woman looked like. After analyzing this, scientists were able to piece together the genome, and determined that the woman had blue eyes, dark skin and dark hair. Not only was DNA found on the birch pitch, but there were microbes that may have been left from her mouth.
This discovery shows that fossilized bones are not the only source of ancient human DNA. Findings like this are fascinating, especially how this piece of chewing gum could last over 5,000 years and still contain DNA and microbes to help us determine specific traits.