Hair
Description
Hair, as well as the animal variants fur or feathers, are keratin structures formed on the outer skin. Keratins are water-insoluble fiber proteins, which also compose finger and toe nails, claws, hooves and horns or scales. In archaeological contexts, they are usually not well preserved unless they have been specifically treated (embalming) or buried under favorable storage conditions (bogs). Mummies often still have hair remnants on which, apart from radiocarbon dating, various element analyses can be carried out to give evidence for the living conditions and diet of humans or animals. Also in modern medicine and forensics certain substances such as drugs can be detected in hair.
Sample properties
Preserved ancient hair and skin usually show traces of preservatives that make chemical or isotope analyses difficult or even impossible. For such purposes, therefore, untreated material should always be used. If this is not available, larger sample sizes are required in order to apply harsher pre-treatment techniques. Information on samples of soft hair pieces such as wool (goats, sheep, camels etc.) is given in the description for textiles. Hair to be used for analysis should be available as clearly macroscopically recognizable pieces.
14C dating
For radiocarbon dating, a small tuft of hair or fur weighing about 30-50 mg should be available. In the case of horn and scales, a piece comprising about half a fingernail is sufficient and also corresponds to an amount of 30-50 mg. The same applies to feathers. If it is known that preservatives or embalming agents have been applied to the pieces/hairs, the sample quantity should be doubled. Please contact the laboratory if the sample quantity is considerably smaller.
Carbon and nitrogen isotope analysis
Nitrogen and carbon isotope ratios in hair or fingernails can provide information about a person’s average diet composition in the last months or years of life. The period represented depends on the length of the hair or nail.
Analyses are possible from a sample size of less than 10 mg.
For hair tufts of a few millimetres in diameter, serial sampling and thus the determination of time-resolved information regarding diet changes is possible.
For conserved/embalmed sample material, correspondingly larger sample quantities are required (see 14C dating)