- U.S. Department of Justice
- Federal Bureau of Investigation
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(Longitudinal Study) |
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National Institute of Public Health Prague, Czech Republic |
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Hospital with Policlinics Prencin, Slovakia |
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Department of Anthropology National Museum of Natural History Washington, DC |
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Introduction |
Materials and Methods |
Results |
Macroscopic Observation |
Microscopic Structure of Hair |
Discussion |
References |
Hair color represents an important variable for comparative purposes in forensic contexts. The color of hair depends on the pigment present, the surface transparency, reflectivity, and other factors. There are two observed pigments that account for the color of human hair—eumelanin (brown) and phaeomelanin (red).
Pigment granules may be fine, coarse, obscure, or absent and may appear streaked or clumped. Their distribution may be central, peripheral, uniform, one-sided, or absent. Random distribution refers to pigment that is found in greater concentrations in some areas of the shaft and in lesser concentrations in other areas of the shaft, with no recognizable pattern. The density of pigment granules appears to be highly correlated with microscopic hair color. It may be absent, light, medium, heavy, or opaque. Ogle and Fox (1999) state that the correlation between hair color and pigment density is very high.
Hair color belongs to a standard set of features used in forensic comparison. It is based on the assumption that hair color can provide useful comparative information even though it can change over time for different reasons.
This study contributes new detail to knowledge of change in hair color by documenting such changes in babies and children from the age of 1 month to 5 years in a white, middle-European population from Prague (Czech Republic). Prague lies about 250 km south of Berlin and about the same distance in the northwest direction from Vienna. The data presented here are especially relevant in cases of missing children or any examination that requires hair comparison from children when considerable time difference is involved in the collection dates.
This study was based on a chronological follow-up of 232 healthy children (114 boys and 118 girls) from Zizkov, a quarter of Prague with about 100,000 inhabitants. The sample surveyed was composed of children born only on Wednesdays. The hair samples were taken at each visit to the health center when the child was 1 month, 3 months, 6 months, 9 months, and 1 year old. After the age of 1 year, the hair samples were collected in 6-month periods until the age of 5 years. A group of approximately 100 hairs was cut as close to the scalp as possible from behind the left ear and fixed with transparent tape to a card (Kapalín et al. 1969). The shade of color of each of these samples was compared visually with 24 shades of the Fischer and Saller color standards (Figure 1), a collection routinely used in physical anthropology and medicine. These standards are available from Siger Hegner, Talstrasse 14, Zurich, Switzerland. All assessments were made by the same observer under good daylight (Glosová 1978) shortly after the cuttings were made. Not all of the 24 color shades marked by capital letters A-Z from the Fischer-Saller standards were used in the final assessment. For comparative simplicity and to focus on major color shifts, the shades were reduced into 6 color groups (Figures 2, 3, and 4) as follows:
1. Very light (A-E),
2. Light (F-L),
3. Light brown (M-O),
4. Brown (P-T),
5. Brown-black and black (U-Y), and
6. Red (I-IV=red; V-VI=red-blond).
For illustrative purposes, examples of hair which correspond in color with selected shades of the standard (marked by letters B, N, T, U, and by numerals IV and V for red hair) are shown with color photomicrographs in Figure 4. Changes in the color, microscopic structure, and thickness of a sample of hair from one girl is shown in color photographs from 1 month to 5 years of age (Figure 5). All photographs are reproduced at the same magnification so that the thickness of the hair is comparable. The girl represented had straight hair. This ensured that the diameter of the hair did not change with its position, which would be the case had her hair been curly or wavy.
Macroscopic
Observation
The distribution of hair color in children from 1 month to 5
years of age is shown in Figure 2
for boys and in Figure 3 for girls.
These figures show the prevalence of the dark hair shades (M
through Y) in children of both sexes in the first half year of
their lives and the shift towards the prevalence of light hair
color shades (A through L) from 9 months to 2 ½ years
of age. Between the ages of 3 and 5 years, the hair becomes progressively
darker. Very light (A-E) and black hair (U-Y) are rare in the
Prague child population. Red hair occurs in 1 to 2 percent of
the studied sample.
Microscopic Structure of Hair
Selected hairs from our study samples were mounted on slides
with Canadian balsam and examined microscopically with a bright
field transmitted light microscope at 1:360 magnification. Photographs
were taken using Polaroid™ color prints. Figure
4 presents the microscopic structure of hairs which appear
macroscopically as very fair (B), light brown (N), brown (T),
brown-black (U), red (IV), and red-blond (V).
The change of hair color, structure, and thickness in the same child (a girl) between the ages of 1 month and 5 years is illustrated by photomicrographs shown in Figure 5. In this individual, hair diameter (measured consistently at the cut end of the hair) approximately doubled between 1 month and 1 year of age. Pigment was found in great amounts in dark hair at one month (shade T). The hair became lighter at the ages of 6 and 9 months and changed to shade K at 3 years. At the age of 5 years the hair became dark again (shade S). The medulla developed at the age of 3. Figure 6 shows the girl at ages when her hair samples were taken. Numbers of hair color shades according to the Fischer-Saller standards are given with each photograph.
The microscopic hair structures useful to the forensic hair examiner include the cuticle, the medulla, and the cortex. The cuticle consists of overlapping scales which cover the hair shaft. It may be thin, thick, mixed, or not even apparent. The medulla is the canal of air or liquid-filled cells in the center of the cortex. Its thickness is usually about one-third of the hair's diameter or less, being relatively thinner than in most mammals. The medulla in human hair may be continuous, interrupted, or fragmentary and may have either a translucent or opaque form. It may also be absent. When the medulla is filled with air, it will appear opaque under a microscope. When the medulla is filled with liquid, it will appear translucent. The cortex, the main body of the hair, consists of keratinized fibers oriented parallel to the long axis of the hair and containing a number of inclusions. The ability to observe the cortical texture may be obstructed by heavy pigmentation (Ogle and Fox 1999).
It was not the intention of this paper to study the reasons for the change in hair color in young children. The dark hair color in babies at birth was explained by Lenz (1925) as a hormonal influence of the mother. Two hairs which macroscopically have the same color may appear differently under the microscope (Reed 1925). Glosová (1978) quotes Rihová (1951), who set forward the assumption that the difference in pigmentation in hair is given by the grade of oxidation of melanin. Acid reaction is found in dark hair, alkaline reaction in light hair, and a neutral reaction in red hair. Hair color may be influenced also by secondary factors, both internal (hormonal factors) and external (effect of sun, washing in alkaline detergents, frequent bathing in sea water), and also by the genetic disposition. Several authors have discussed the problems of the change of hair color in children due to age but have not followed these changes chronologically (Dokládal 1977; Drobná 1964). The data presented here suggest that, at least in the sample studied, these changes can be profound and must be considered in relevant forensic investigations.
This paper provides information
that general hair color in Prague children can change substantially
with increasing age. Note, however, that this paper does not
address the important factors of color variation along the length
of a hair or variation among hairs from various locations on
a single person. Such variation is deserving of additional research
attention but falls outside the limits of the project reported
here.
Forensic scientists should be aware of such changes in hair color
in babies and preschool children in their work. Obviously, the
difference between the collecting times of the known and questioned
samples also can be an important factor in assessing hair color.
Dokládal, M. The Color of the Head Hair in the First Ten Years of Life. Medical Faculty, J. E. Purkynje University, Brno, 1977.
Drobná, M. Pigmentation of skin, hair, and body hair in Bratislava girls from 3 to 20 years, Acta Facultatis Rerum Naturalium Universitatis Comenianae (Anthropologie) (1964) 9.
Glosová, L. Change in the Pigmentation of Hair in Children Under 5 Years of Age. Unpublished thesis, Charles University, Third Faculty of Medicine, Prague, 1978.
Kapalín, V., Kotásková, J., and Prokopec, M. Physical and Mental Development of the Present Generation of Our Children. Academia, Prague, 1969.
Lenz, F. Muss das Nachdunkeln der Haare als Dominanzwechsel aufgefast werden?, Archiv fur Rassenbiologie (1925) 16:428.
Ogle, R. O. and Fox, M. J. Atlas of Human Hair. CRC Press, Washington, DC, 1999.
Reed, T. E. Red hair color as a genetical character, Annals of Eugenics (1925) 17:115.
FORENSIC SCIENCE COMMUNICATIONS JULY 2000 VOLUME 2 NUMBER 3
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