Marked limb bilateral asymmetry in an agricultural endogamous population of North India

The purpose of this study is to evaluate directional asymmetry in the most commonly measured dimensions of limbs in adult male Gujjars of North India.

The sample for this study is based on 967 adult male Gujjars ranging in age from 18 to 30 years settled in subHimalayan region in the foothills of Siwaliks surrounding Chandigarh city in North India. The data comprise nineteen anthropometric measurements taken on left and right side of each subject. Gujjars are one of the major caste groups of India having agriculture as the main occupation. This group is also homogeneous in terms of ethnic composition, language, and religious affiliation. Using appropriate statistical methods, the bilateral asymmetry was evaluated in the human body.

The results indicate that significant bilateral asymmetry exists in some of the limb dimensions. Upper extremity dimensions are more asymmetric than that of lower extremity dimensions. Most of the arm dimensions are significantly larger on the right side except hand length and triceps skinfold in younger sample and triceps skinfold in older sample, which are significantly larger on the left side. Most of the upper extremity dimensions are larger on the right side, however; most of the lower extremity dimensions are larger on the left side.

Marked directional asymmetry exists in 13 measurements out of a total 18 taken for the study. This significant right-sided asymmetry may be attributed to the fact that individuals have normal tendency to favor the right side for power activities involving upper limbs, i.e., throwing for distance, sports activities, and in this investigation, working with agricultural tools like Khurpa, Datti, Kassi (Indian agricultural tools) for long durations. More frequent use of the preferred side results in heavier or stronger muscles of that side and consequently heavier and stronger bones.