370 JOURNAL OF COSMETIC SCIENCE A D APPROXIMATE HAIRLENGTHS (CM) From B From A Midpoint 12.7 to 17.7 22.9 to27.9 E 25 to 33 38 to 46 35.5 F 46 to 51 58 to 64 55 G 61 to 76 74 to 89 75 H 89 to 107 102 to 119 104 I 117 to 142 130 to 155 136 j 147 to 180 160 to 193 170 A = Frontal B = Crown C = Occipital [] = Chin E = Shoulder, F = Lower shoulder blade G = Waist H = Buttocks I = Knee and J = Ankle. The distances from Ato B and B to C are 10.2 and 12.7 cm plus or minus 1. Figure 1. Measurements of anatomical positions relating to free-hanging hair lengths. CALCULATIONS (ESTIMATES) FOR THE USA AND LARGER POPULATIONS Four data points from the theme park studies expressed as hair lengths based on the anatomical site measurements (Table V--Approximate midpoints) were plotted against the natural logarithm of the percentage of the population between sites (Table III), providing the graph in Figure 2. This represents the use of 3,208 data points rather than the total of 24,300 from our theme park studies. The equation representing this straight

SCALP HAIR LENGTH 371 Table IV Anatomical Measurements (cm) From Crown of Six Panelists* Sex F F F M M M Avge Range Height 163 170 158 191 178 185 174 158 to 191 Shoulders 25.4 27.9 27.9 30.5 30.5 33 29.2 25.4 to 33 Bottom shoulder blades 45.7 48.3 45.7 45.7 48.3 50.8 47.4 45.7 to 50.8 Waist 61 63.5 61 73.7 68.6 76.2 67.3 61 to 76.2 Buttocks 91.4 94 88.9 101.6 104.1 106.7 97.8 88.9 to 106.7 Knees 119.4 124.5 116.8 142.2 132 134.6 128.3 116.8 to 142.2 Ankles 152.4 160 147.3 180.3 170.2 172.7 163.8 147.3 to 180.3 * From frontal area add 12.7 cm. The actual length of the hair pulled taut will always be longer than the above measurements the difference depends on the amount of curvature in the hair. Assume about a 5% additional length for taut hair, although it will be longer than 5% if the hair is very curly or if it is braided. If the hair is very straight, the taut length may be less than an additional 5%. Table V Anatomical Sites and Approximate Hair Length Rounded Off to Nearest Centimeter From B Approximate Approximate Approximate From A range midpoint* midpoint + 5%** Shoulder-length 25 to 33 35 to 43 25 to 43 34 _+ 9 Lower-shoulder-blade-length 46 to 51 56 to 61 46 to 61 53.5 _+ 8 Waist-length 61 to 76 71 to 86 61 to 86 73.5 _+ 15 Buttocks-length 89 to 107 99 to 117 89 to 117 103 _+ 14 Knee-length 117 to 142 127 to 152 117 to 152 134.5 _+ 18 Ankle-length 147 to 180 157 to 190 147 to 190 168.5 _+ 22 36-+9 56-+8 77-+ 15 108 -+ 14 141 -+ 18 177 -+ 22 A is the frontal area, and B represents the crown area. A = B + 10.2 cm (4 inches). * Represents the approximate length of hair as it hangs free from the midscalp. ** Approximates the taut length of hair from the midscalp. See explanation in Table V. line (A) was used to estimate the approximate numbers of people in the USA at several hair lengths within and beyond the limits of the graph: Y = 5.693 - 0.0945X (A) Y = In% of population, and X = hair length in centimeters. R 2 = 0.998 and is highly significant. For all calculations from this equation, one should use either the average lengths from the anatomical sites of Table IV or if other individual lengths are used, one should choose lengths at least as far apart as the plus or minus values for the averages listed in Table IV otherwise the added percentages will exceed 100%. Extrapolation of this line, Figure 2, permits us to estimate percentages and numbers of people in the USA with even longer hair lengths. We used 183 cm (six feet) as the cutoff point for extrapolation, based on information provided by Figure 3 and described later in this paper. In the theme park studies, no person was observed with hair longer than buttocks- length. However, hair much longer than that exists and has been reported from many different sources (3-8). Hair down to the ankles has been observed for many persons, including the beautiful hair of the entertainer Crystal Gayle (see Figure 4). Equation A