samples including bone, hair is formed at a constant rate and,
once formed, does not show further biogenic turnover. In
contrast to other soft tissue samples, which are degraded
after burial for long periods of time, hair samples have been
found to be relatively resistant to degradation. Although hair
samples from archaeological burials look inert to the naked
eye, these samples are also subject to biodegradation [6].
Because hairs found during archaeological excavations have
varying degrees of degradation, depending on the conditions
and duration of burial, it is important to determine the timedependant
morphological changes in hair.
To understand the morphological changes that occur in
hair during long-term burial, it is necessary to consider
changes in histological morphology of the hair caused by
various factors. For example, environmental factors including
sunlight, air pollution and wind, have been found to
induce histological changes in the hair cuticle and cortex,
ultimately leading to the destruction of the hair shaft [7–10].
In addition, histological changes in hair structures are caused
by various pathological states [11–13]. For example, in
individuals with alopecia areata, keratinocytes in the hair
are damaged by an autoimmune mechanism, and these
defects in cortical cells within the hair shaft correlate with
the pathophysiology of the disease [9,14].
Many hair samples taken from sites of archaeological or
forensic investigation have undergone weathering for long
periods of time. Although changes in the histological structure
of the hair have been documented during various
conditions, there have been few studies on morphological
changes of hair that occur during prolonged weathering.
Thus, an ultramicroscopical study on the morphological
changes that occur in weathering hair samples would be
useful. We therefore undertook to document the weathering