BODY AREA DETERMINATION
Unlike other animals, humans exhibit a wide variety of hairs on their bodies; why humans have hair where they do is of interest to evolutionary biologists, and one recent theory is discussed in “In More Detail: Hairless and Flea-free.” The characteristics of these hairs may allow for an estimation of body area origin. The typical body areas that can be determined are head (or scalp), pubic, facial, chest, axillary (arm pits), eyelash/eyebrow, and limb; typically, only head and pubic hairs are suitable for microscopic comparison, as shown in Figure 1. Hairs that do not fit into these categories may be called transitional body hairs, such as those on the stomach, between the chest and the pubic region. Table 1 lists the characteristics generally associated with the different body hair types. Buckling is an abrupt change in direction of the hair shaft with or without a slight twist. Shouldering is an asymmetrical cross section of hairs. In some instances, it may be difficult or impossible for the forensic scientist to make a clear decision as to whether a hair is “chest” or “axillary” in origin; it may also not matter to the circumstances of the crime. Labeling the hair as a “body hair” is sufficient and may be the most accurate conclusion given the quality and nature of the hair.
FIGURE 1 Unlike other animals, humans exhibit a wide variety of hairs on their bodies. The characteristics of these hairs may allow for an estimation of body area origin. The typical body areas that can be determined are head (or scalp), pubic, facial, chest, axillary (armpits), eyelash/ eyebrow, and limb. Hairs that do not fit into these categories may be called transitional body hairs, such as those on the stomach, between the chest and the pubic region.
Table 1 General Descriptions of Human Body Area Hair Traits
This determination may have important consequences for a case: One of the authors (MMH) worked a case involving the identification of an adult pubic area hair on a preadolescent victim. A girl of that age could not have produced a pubic area hair: Those hairs are generated by the hormones associated with puberty. DNA from the hair was the same as that from the suspect; this, in addition to overwhelming trace evidence associating the suspect with the crime, led to a guilty plea (see Ryland and Houck (2000) for more information).
