Signatures of high altitude adaptation in Tibeto-Burman tribes of the Darjeeling Hill Region

Abstract

Objectives: The long-term isolation, endogamy practices, and environmental adaptations have shaped the enormous human diversity in India. The genetic and morphological variations in mainland Indians are well studied. However, the data on the Indian Himalayan populations are scattered. Thus, the present study attempts to understand variations in the selected parameter among four Tibeto-Burman speaking ethnic tribal populations from the Darjeeling Hill Region (DHR) in the Eastern Himalaya Biodiversity Hotspot region of India. Methods: A total of 178 healthy male individuals (Lepcha 98, Sherpa 31, Bhutia 27, and Tibetans 22) living at an altitudinal range of 1467–2258 m above the sea level were studied for the 10 parameters namely, weight (kg), height (cm), body mass index (BMI) (kg/m2) systolic and diastolic pressure (mm of Hg), pulse rate (per minute), saturation of peripheral oxygen (SPO2) (%), hemoglobin (g/dl), hematocrit (HCT) (%), and blood glucose (mg/dl). The data was statistically analyzed using analysis of variance and multiple linear regression methods. Results: Our analysis revealed comparatively lower hemoglobin and HCT levels, and higher systolic and diastolic blood pressure in the Sherpas followed by the Tibetans. This may be reflecting the persistence of high-altitude adaptation signatures even in lowlands. Interestingly, the Tibetans differed significantly from other populations in terms of their higher body weight, height, and BMI. Conclusion: Thus, our study showed the persistence of high altitude signatures in Tibetans and Sherpa inhabited the DHR. Additionally, we also observed significant differences in the anthropometric and physiological parameters among the Tibeto-Burman populations of the DHR.