It's easier to analyze than collagen. Instead of working with many of grams of bone, which can destroy a skeleton, hair requires only a little trim around the size of the head of a pin. I once asked for one of the teeth of the Ice Man when I thought I might pursue the collagen technique, and I was told I didn't have a prayer. A snippet of hair, it seems, posed no problem. To break it down, organisms have to excrete an enzyme on the outside of their cells to attack the very rigid structure, and not many organisms besides some fungi and a few bacteria are capable of it.
Hair stays resistant to any kind of decay.
Macko hopes to hone the technique by using his mass spectrometer to measure the exact essential amino acids present in the hair. Presently he's able to ascertain the general food groups, such as fish, meat, grain, bean or shellfish. With less ambiguity about what foods were consumed, he hopes to be able to further deduce ancient behaviour. My laboratory is one of the few that has ever measured isotope signals of amino acids. We're just having fun now.