Solving Crimes with Saliva: The Microbial Trail

You're a detective trying to solve a crime. Figuring out when and who left behind a saliva stain can be a big clue. Right now, scientists are looking into how the bacteria in old saliva stains change over time. They want to find out if these changes can tell us how long ago the stain was left and whether it came from a man or a woman. In this study, scientists collected saliva stains that had been sitting indoors for up to 140 days. They used a special technology to look at the microbes in these stains. They found that certain types of bacteria, like Streptococcus and Rothia, became less common over time. Interestingly, they also found that the bacteria in stains from men and women were different.Using this information, they created a model to predict how long a stain had been there. This model was pretty accurate, with an average error of only 9. 59 days. They also made a model to guess the sex of the donor, which was right 84. 21% of the time. This shows that old saliva stains still have important information for solving crimes. By studying the microbes, we can learn more about when and who left the stain behind.