Estimation of stature by using the dimensions of the right hand and right foot in Han Chinese adults

The Han Chinese people are the main ethnic group in China and the largest ethnic group in the world. The dimensions of the hands and feet have been successfully used for the estimation of stature. A total of 26,927 healthy adult subjects, comprising 13,221 men and 13,706 women, were recruited. The survey samples were chosen through random cluster sampling. The mean values were significantly higher in men than those in women for all measurements (P<0.001). All the measurements showed a statistically significant correlation with stature (P<0.01). The combination of the right hand length and the right foot length was the best predictor of stature because it had the lowest standard error of estimate. The use of multiple regression equations yielded better results than did the use of linear regression equations. The accuracy of stature prediction ranged from ±4.81 to ±6.39 cm. The present study was of great importance with regards to improving the physical anthropology database of ethnic groups in China.


INTRODUCTION
Forensic scientists are interested in the estimation of stature because of its importance in personal identification. There is a relationship between each part of the body and the whole body. The hand and foot dimensions may represent a person's identity. Human stature is an anatomical complex of linear dimensions (Moorthy et al., 2014;Uhrová et al., 2015;Zaher et al., 2011).
A previous study has confirmed that the correlation coefficients for stature and right hand/foot length are equal to those for stature and left hand/foot length (Uhrová et al., 2015). The aim of this study was to assess the relationship of the dimensions of the right hand and right foot with the stature, and to provide equations for stature estimation in Han Chinese adults. The Han Chinese people are the main ethnic group in China and the largest ethnic group in the world. The results of our research have practical use in the forensic field as well as in the field of sport and physical anthropology. The present study is of great significance in improving the physical anthropology database of ethnic groups in China.
The fact that the equations derived from one population cannot be used for other populations needs to be taken into the consideration, as body dimensions show ethnic variations due to genetic factors and environmental conditions. A single formula cannot represent the nationwide or worldwide population (Fawzy and Kamal, 2010;Jasuja et al., 1991;Krishan et al., 2012). It would be useful, however, to assess whether this method of stature estimation has forensic potential in other populations.

RESULTS
The descriptive statistical results of means and standard deviations for stature, right hand measurements, and right foot measurements are shown in Table 1. The mean stature in men was higher than that in women. The mean values were significantly higher in men than those in women for all measurements (Table 1).
The correlation coefficients for stature and right hand/foot measurements are shown in Table 2. All the measurements showed a statistically significant correlation with stature (P<0.01). In men, the highest correlation coefficient was between the stature and right foot length (r=0.602), and the lowest was between the stature and right hand breadth (r=0.240). Similarly, in women, the right foot length resulted in the highest correlation coefficient (r=0.565), whereas the right hand breadth showed the lowest correlation (r=0.175) with stature.
The linear regression equations for the estimation of stature from the right hand and right foot dimensions are shown in Table 3. The regression coefficients are significant for all parameters. For the analysis of right hand and right foot measurements, the standard error of estimate (SEE) ranged between ±5.251 and ±6.385 cm for men and between ±4.850 and ±5.788 cm for women. In Table 3, the right foot lengths showed the lowest SEE. Therefore, the right foot length would provide the most reliable stature estimation.
Tables 4 and 5 show that the combination of right hand/foot length is the best predictor of stature because it had the lowest SEE; for men, it was the combination of right hand length and right foot length (SEE±5.188 cm), and for women it was the combination of right foot length and right hand length (SEE±4.822 cm). Tables 4 and 5 show that multiple regression equations resulted in lower SEE values than did linear regression equations, ranging between ±5.179 and ±6.128 cm for men, and between ±4.812 and ±5.636 cm for women.

DISCUSSION
In this study of Han Chinese adults, the stature and right hand/foot dimensions were found to be higher in men than in women. The results were consistent with those of previous findings (Agnihotri et al., 2008;Kanchan et al., 2008;Krishan and Sharma, 2007;Rastogi et al., 2008;Sen and Ghosh, 2008;Uhrová et al., 2013;Uhrová et al., 2015;Zeybek et al., 2008;Zheng et al., 2013;Zheng et al., 2015). The values for Han Chinese men were higher than those for Han Chinese women, with a significant difference between sexes ( Table 1). The mean values of men were higher than those of women owing to their later maturity and growth cessation. Many previous studies have confirmed the presence of a positive correlation between several different body parts and stature (Agnihotri et al., 2007;Krishan and Sharma, 2007;Uhrová et al., 2015). We found that the highest correlation coefficient was between stature and right foot length in men and women, whereas the correlation coefficient between stature and right hand breadth was the lowest.
The study showed that the ratios of foot dimensions to stature changed considerably with age and sex. Consequently, the regression equations that include these variables yielded more reliable results (Atamturk and Duyar, 2008). Our results indicated that age and sex should be taken into consideration when predicting human stature.
The results of this study showed that the right foot lengths with the lowest SEE would provide the most reliable stature estimation. The regression equations of stature from the right foot length for Han Chinese men and women were both statistically significant in the test of the regression effect. There was a significant linear regression relationship between stature and right foot length, and stature could be estimated by using the following regression equations: S=88.522+3.225RFL for men and S=89.811+2.941RFL for women. The SEE values of multiple regression equations    Zhang, X., et al. Sci China Life Sci   Estimation of stature from right hand and right foot dimensions by using regression equations has great implications and usefulness for physical and forensic anthropology. Because there is no sampling study for left hand/foot dimensions, the right foot lengths would provide the most reliable stature estimation. This study provides new forensic standards for the estimation of stature from the right hand and right foot measurements of Han Chinese adults.

Materials
In this study, measurements taken from 26,927 healthy adult subjects (13,221 men, 13,706 women) currently residing in China were examined. The subjects were required to sign a consent form and complete a questionnaire containing basic demographic data and general questions, e.g., sex, age, and ethnicity. The subjects were between 19 and 75 years of age (mean age of men: 45.1±16.3 years, mean age of women: 45.0±15.6 years). All subjects were healthy local Han Chinese people who were native to their areas of residence for more than three generations. The modern Chinese population can be divided into the northern and southern groups, separated by Qinling Mountains and Huaihe River. The study included 11,734 northern Han (5,842 men, 5,892 women) and 15,193 southern Han (7,379 men, 7,814 women) subjects. The survey samples were chosen by means of random cluster sampling. These Han Chinese subjects were categorized in five subgroups according to their age ranges: 19-29, 30-39, 40-49, 50-59, and 60 years and older. The sampling locations included Sichuan, Inner Mongolia, Guangdong, Liaoning, Henan, Hebei, Shaanxi, Gansu, Jiangxi, Jiangsu, Hunan, Hainan, Anhui, Shanxi, Shandong, Zhejiang, Fujian, Hubei, Yunnan, Guizhou, Jilin, and Heilongjiang.

Measurements
Stature was measured by using an anthropometer. For stature, the distance from the vertex to the floor in the anatomical position with the head oriented in the Frankfurt plane was measured (Figure 1) (Martin and Saller, 1957). For hand length, the distance between the midpoint of the distal transverse crease of the wrist to the most anterior projection of the skin of the middle finger was measured .
For hand breadth, the distance between the most lateral point on the head of the second metacarpal to the most medial point on the head of the fifth metacarpal was measured .
For foot length, the maximum distance between the heel (pternion) and the longest toe (akropodian) (Hemy et al., 2013) was measured.
For foot breadth, the distance between the most prominent point on the medial side of the foot to the most prominent point on the lateral side (which corresponds to the heads of the first to fifth metatarsals) (Hemy et al., 2013) was measured.
With respect to establishing the reliability of obtaining stature and right hand and right foot measurements, we have verified that the degree of measurement error and reliability are well within acceptable standards (R>0.9; rTEM<5%) (Perini et al., 2005;Knapp, 1992;Reynolds et al., 2008).

Statistical analysis
The data were statistically analyzed by using SPSS 17.0 for Windows and Microsoft Office Excel 2003. The significance of sex differences was tested by using an independent t-test. The association between stature and right hand or right foot measurements was determined by using Pearson correlation analysis. Linear regression analysis, stepwise regression, and multiple regression analyses were used to calculate the equations for the estimation of stature from right hand and right foot dimensions.

Compliance and ethics
The author(s) declare that they have no conflict of interest.