DISTRIBUTION O F RED HAIR ACCORDING TO AGE NICHOLAS MICHELSON Department of Anthropology, Columbia University ONE FIGURE In a previous investigation* Franz Boas and I were able to prove that there exists a correlation between the type of pigmentation of the hair and the rate of graying. Among whites light hair becomes gray later than that of darker hue. Earlier research has not dealt with the relative frequency of red hair in relation to hair of other colors in the same individual, excepting in so f a r as there are some remarks pertaining to differences of color of hair of the head and the body.3 The present study is devoted to the numerical relation of red hair of the head to that of other hues as well as to grayness. The investigation of hair samples showed that in blond, brown and black hair, red hairs may be found in varying numbers, sometimes a few scattered hairs only, sometimes large amounts. When classified according to age, the ratio of those individuals having any red hair does not seem to be stable. I have at my disposal hair specimens of 2397 male whites, clipped from the right temple. Out of that populat,ion 435 persons showed a red component in their hair. The distribution of nationalities of these individuals was : 214 Irish, l Investigation carried on under the auspices of the Council f o r Social Research. 'The graying of hair. Am. J. Phys. Anthrop., 1932, XVII, 213-228. For literature see : Chemische und geuetische Uutersuchungen an menschlichen Pigmenten, speziell demjenigen des Haares. K. Saller and F. Maroske. Zeitschr. f u r Konstitutionslehre, 1933, XVII, 279-317. Also : Pigmentation in the old Americans, with iiotes 011 graying and loss of hair. Ale; HrdliEka. Am. J. Phys. Anthrop., V, 110. 2, May, 1922. 407 AMERICAN J O U R N A L OF PFWSICAL ANTHBOPOLOGY. VOL. XVIII, NO. JANUARY-MARCH, 1934 3 m a TABLE 1 84.8 145 98.6 102 -- 9.9 17 0.9 1 77.8 ag= Total frequency Per cent of total for all ~ 81.8 1926 ___ 85.9 ~ _ _ _-~ _- 213 - -79.6 ___ 199 -- _ _ 80.9 224 -~ 78.6 294 80.7 276 7 5 9.8 1.6 24 9.4 26 9 I 3 1.8 5 I 3 1.1 -__ -_ Z.9 8 3 0.8 1.5 -____ 3 5 I 1 2 0.3 1 0.7 1 0.3 0.7 2 1 0.4 1 - I __..- 1 1 1 0.8 0.8 0.9 --____ _ 1 2 2 1 0.4 0.7 0.7 0.4 1 0.3 0.9 - -_____ :.4 S.8 1.6 0.4 9.8 6.8 1.6 l l 0.9 37 22 __ i7 -__ __ 220 4.4 7 3 6 0.s 0.9 0.1 0.8 -______ 7 _ 0.4 _ _ _0.4~ __ _ __ ._-__ __ __ __ -- 9.6 9.6 1.8 1.2 .__ -~1 8 . 4 11 ~ 11.0 9.6 13 8.1 --- 10.5 41 __ 13 36 ~ 0.9 13.0 __ 9.0 9.0 ~ 0.9 -~~-__ _ _ __ 1 0.6 6 3 3 23 3.6 1.3 1.3 10.0 81.0 __ __ 9 6 1 39 231 187 -__ - 65 and over 6064 55-59 50-54 45-49 40-44 35-39 4 0.6 2.8 1 1.8 _ _ __ 2 -__- 60 4.8 171 1.9 109 3.2 1 2 0.4 1 1 0.8 __ 1 1.1 - b.0 - 0.4 9 __- 0.4 9 I I 2125014.9 277 2.8 ___- - OJ 0.7 - 6 0.4 -_ _ 0.4 1 5 2 0.8 _ _ 1 ~ 342 1.9 1 0.8 - _ _ 374 4.3 4 0.4 ___ - ~~ 1.1 4 1 __ 0.9 0.9 0.7 __ _ - 1 3 1.9 0.4 __ _ - 231 3.0 - --- 0.9 1 - ___~- 1.8 2 -_ 1 0.9 1.7 1.7 1.7 -- ___- ~ 9.9 1 -__- 91.7 -. __ 1 5-99 35.89 90-94 - 1 -I--- 10-14 15.11 i 2 __ 5.9 I 55 - -~ Less than 5 __ _ _ _ _ _ ~ 30-34 25-29 20-24 I- PER OUNT BED HAIR Per cent of red hair at each age. Red in pcr csnt of red, brown and blaok. Figures in roman are frequencies. Figures in italics are in per oent of total frequency for the age group - 409 DISTRIBUTION OF RED H A I R 48 northern Europe, 31 Jewish, 26 German, 11 Scotch, 19 southern and central Europe, and 86 not given. Their distribution seemed to be about the same in all age classes. The same method of counting was applied as described in the previous paper. Cases of light hair were too few to give valid results. For this reason only hair darker than a.standard brown was considered. Doubtful cases in which red and brown could not be clearly distinguished were not taken into consideration. The differential count of each hair sample embraced four combinations: red with or without gray; red and dark with or without gray. The occurrence of the hues: red, brown and black as well as of grayness was calculated in per cent. The percentile frequencies were tabnlated. Figure 1 illustrates graphically the per cent of a given population (2397 individuals) having any red hair at different ages. This tracing shows an increase of the frequency of individuals with red hair between 32 and 47 years of age, then some decrease until the sixty-fifth year, followed apparently by a more rapid decrease. The same figure contains the average per cent of red hairs in the total population. It will be noticed that these values decrease slowly from 22 to 32 years and then seem to rise slowly. This relation becomes clearer in the graphical presentation of the ratios between red and dark, excluding gray hair, given in the same figure. Unfortunately the number of cases from which the initial rapid drop is determined is very small. On the other hand, the steady increase from 32 years on is well established. Arranged in larger groups the increase of red hair in proportion to brown and black hair appears clearly also. TABLE 2 Frequencics among all those having any red hair (455 cases) Lms than 6 t o SO per cent SO per cent A m b iearr 6 p a cent red rcd red and over 20 to 39 7.5 4.4 2.1 40 t o 54 11.4 6 .? 2.9 55 and over 8.0 6.3 3.7 410 NICHOLAS MICHELSON I Fig.1 Average amount of red i n total population (sum of frequencies of red divided by the number of those with red, brown and black). Frequency of individuals having any red (number of those with any red hair divided by number of those with red, brown and black). Frequency of red for those having any red hair (sum of frequencies of red divided by total number of individuals with any red hair). 411 DISTRIBUTION O F RED HAIR Among all those having any red hair the following ratios between the frequencies of those with various percentages of red hair as against the total number of those with any red hair in the same age group occur: TABLE 3 Age in Year8 20 t o 39 40 to 54 55 and over 5 Frequencies (435 cases) Lesr than 5 to 2 9 p e r cent per cent red TEd 53.6 54.3 44.4 35.7 32.0 35.0 9 0 per cent red and over 10.7 13.7 20.6 I t might be assumed that the relative increase of red hair with increasing age is due to the earlier graying of dark hair. An attempt to calculate this effect on the basis of the value for rapidity of graying previously obtained shows that such an explanation is inadequate. At this point it must be emphasized that the increase with increasing age of the frequency of the combined occurrence of red and black hairs, as found among individuals with more than 30 per cent of red hair, does not make it clear by what process this increase is brought about. Red hair is liable to become darker and we might expect a decrease of redness among those having any red hair, but the observation shows the reverse for higher percentages of red. Since the graying does not account for it there would seem to be some other reason for the red hair in the older groups. While classifying the hair samples from the point of view of pigmentation, it was observed that the series containing red hairs showed also a certain number of polychrome hairs which were red at one extreme and black at the other; or in which red and black were mixed and yielded an impure reddish brown. In other hairs such hues as black and brown or red and brown occupied different sections of the same hair shaft. This phenomenon cannot be attributed to fading due to exposure to light, since there seems to exist a correlation between the frequency with which one finds a variety of colors in individual hairs and progressive age. Altogether there 412 NICHOLAS MICHELSON were 27 persons with distinct black and red sections in the same hair; 23 persons with red and brown, and 11 persons with black and brown. Nine persons showed black and red to combine or almost to fuse into a dirty brown. Microscopy does not throw any light upon the problem as yet. Two examples may be cited, details being superfluous. First. A hair, about 1 inch in length, was removed in toto from the author's eyebrow. The proximal part of the shaft has a reddish hue which turns brown toward the center of the hair and black at the tip. This hair is somewhat coarse. TABLE 4 Mixed colors in individual hairs ED B R O W N AND BLAOB AGE YEAEB Absolute numbers ?er cent of total numbers Absolute numbers 'er cent of total numbers 1 11 28 11 11 8 70 9.1 15.5 20.9 8.4 16.2 44.4 16.2 0 2 12 7 8 7 36 0 2.8 9.0 5.3 11.8 38.9 8.3 ~20-29 30-39 40-49 50-59 60-69 70 and over All ages CED AND BLAOK ONLY ALL MIXED OOLOBS Absolute numbers lpe\tt$t Of I 1 13 40 1 18 19 _ 15 _ 106 1 9.1 18.3 29.9 13.7 28.0 83._ 3 24.5 =I I Absolute numbers 11 71 134 131 68 18 ~ _ 433 Dersons Although the age distribution is not convincing, it suggests an increase of hairs of mixed color with increasing age. Two samples showing red in combination with blond were not included. Microscopically there is no difference between the morphological characteristics of a red hair and the red section of this multicolored hair; nor do the brown or black sections reveal any deviation from uniformly brown or black hairs. Second. A hair removed from the temple of a man 90 years of age. The hair consists of a tapering white part, a central black and a (basic?) red portion. Microscopically, each section of the hair resembles normal white, red and black hairs respectively. Table 4 illustrates the age distribution of persons whose hair samples displayed a combination of hues in individual hairs. ~ - DISTRIBUTION OF RED HAIR 413 What is the explanation of the co-existence of different hues in a hair? The most plausible assumption would be that we are dealing with a selective depigmentation. Dark hair must often contain brown as well as red pigment. If the dark element should become less and less potent in the hair of the graying person, the presence of the red pigment would become more apparent. Thus, despite the darkening and graying of all hairs with the advance in years, a relative increase in redness would develop in single hairs either as a whole or in parts of the hair. Until we have learned more about the chemistry and function of the pigments, we may venture to advance this theory. At the close of this presentation I would like to express my gratitude to Prof. Franz Boas, who directed this work, and my indebtedness to Miss Bertha Cohen, who executed the tabulations. SUMMARY 1. Out of a total of 2397 white adult males from whose right temple were clipped hair samples, 435 persons showed in their hair a red component. The series containing red hair was classified from the point of view of pigmentation. Differential counts of each hair sample were made. The occurrence of the various hues was expressed in percentile frequencies for each age group. There was found an increase of redness between 32 and 47 years of age, then a slight decrease to the sixty-fifth year; then again an increase up to the seventieth year of age, followed by a terminal decrease. The cause of this rhythm is not known. 2. The association of colors in the individual hairs was studied. Multicolored hairs, rare as they are, seem to increase in frequency a t certain age groups. 3. It seems plausible, though it cannot be established with certainty, that dark pigmented hairs contain the red color component and that the latter becomes more apparent with the advance of age when the hair undergoes senile changes.