Using delicate lasers to ionise but not burn difference sections of your hair for precise chemical analysis, this new forensic method can theoretically tell what you ate and where you were in the world on an hour by hour basis. (Usually, the entire hair gets mashed up into one vague average sample.)
"Carbon tells you what you're eating, but nitrogen could tell you whether it's meat or plants. Oxygen isotopes vary with the water cycle, and sulfur with bedrock, so they're location proxies," Sessions said. "Put them together, and you've got some really powerful data in space and time."
The laser is of the ultraviolet variety and punches holes 50-micron wide holes out of hairs, which the o's of can be used for mass spectrometry. [RCMS via <a href="http://www.wired.com/wiredscience/2011/04/forensic-laser-ablation/"wired]