Life style leaves chemical traces in hair. In horses, the analysis of tail hair is especially suited as the length of the hair can provide information over a long period of time. Determining the exact period of time that corresponds to a segment of hair is not trivial. Hair does not grow at the same rate in all horses. Researchers have now solved this problem. They developed a method to correctly assign individual hair growth to seasons and thus to a specific time frame.
from Geochemistry News -- ScienceDaily http://ift.tt/1H1QJfL