Isotope analysis
A recent development in forensic science is the isotopic analysis of hair strands. Hair has a recognisable growth rate of 9-11mm per month or 15 cm per year. Human hair growth is primarily a function of diet, especially drinking water intake. The stable isotopic ratios of drinking water are a function of location, and the geology that the water percolates through. Sr, Sr and oxygen isotope variations are different all over the world. These differences in isotopic ratio are then biologically 'set' in our hair as it grows and it has therefore become possible to identify recent geographic histories by the analysis of hair strands. For example, it could be possible to identify whether a terrorist suspect had recently been to a particular location from hair analysis. This hair analysis is a non-invasive method which is becoming very popular in cases that DNA or other traditional means are bringing no answers.
Hair removal
Many men in Western cultures shave their facial hair, so only a minority of men have a beard, even though fast-growing facial hair must be shaved daily to achieve a clean-shaven or hairless look. Some men shave because they cannot grow a "full" beard (generally defined as an even density from cheeks to neck), because their beard color is different from their scalp hair color, or because their facial hair grows in many directions, making a groomed look difficult. Some men shave because their beards are very coarse, causing itchiness and irritation. Some men grow a beard or moustache from time to time to change their appearance.