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Home/Anthropology/Mains PYQ/2014/Paper I/Human Genetics & Human Biology
UPSC MainsAnthropology Optional Paper I 2014 15 Marks Model Answer Available

High Altitude Stress and Cardio-respiratory Adaptation — 2014 Paper I

Question · 2014 · Paper I · 15 Marks

What are the stresses at high altitudes ? How do better cardio-respiratory functions help the native highlanders in combating low environmental pressure ?

Model Answer

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Approach

  • Demand of Question: Identify major environmental stresses at high altitude and explain how enhanced cardio-respiratory adaptations help native highlanders cope with hypobaric hypoxia.
  • Structuring the Response: Describe altitude stresses first, then explain ventilatory, circulatory and haematological adaptations.
  • Key Dimensions to Cover: Hypobaric hypoxia, cold, UV radiation, hyperventilation, haemoglobin, capillarization, cardiac output, Tibetan and Andean adaptations.

Model Answer

Introduction: High-altitude environments impose several stresses, the most important being hypobaric hypoxia caused by reduced atmospheric pressure and consequently lower partial pressure of oxygen.

Major high-altitude stresses

  1. Hypobaric hypoxia
  2. Cold temperature
  3. Low humidity and dehydration
  4. High ultraviolet radiation
  5. Strong winds
  6. Reduced physical work capacity

Among these, hypoxia produces the greatest physiological challenge.

Thus:

High altitude → Low barometric pressure → Low oxygen availability → Tissue hypoxia

Cardio-respiratory adaptations

  1. Increased ventilation

Native highlanders show efficient ventilatory responses that improve oxygen uptake in the lungs.

Greater ventilation → More oxygen enters alveoli

Tibetan highlanders, in particular, characteristically maintain relatively high ventilation.

  1. Enhanced oxygen transport

In many Andean populations, increased:

  • haemoglobin concentration;
  • red blood cell mass

helps carry more oxygen per unit of blood.

Thus:

More haemoglobin → Greater oxygen-carrying capacity

Excessive erythrocytosis, however, can increase blood viscosity, so this adaptation has limits.

  1. Improved pulmonary function

Native highlanders often have relatively larger lung volumes and efficient pulmonary diffusion, facilitating oxygen transfer from:

Alveoli → Blood

  1. Cardiovascular efficiency

At high altitude, circulation must maintain adequate oxygen delivery to tissues.

Important responses include:

  • regulation of cardiac output;
  • efficient peripheral circulation;
  • improved tissue oxygen extraction.
  1. Greater capillary supply

Enhanced capillary density in tissues can reduce diffusion distance between blood and cells.

Thus:

More capillaries → Better tissue oxygenation

Population-specific patterns

High-altitude adaptation is not identical everywhere.

Andean highlanders generally show greater reliance on elevated haemoglobin concentrations.

Tibetan highlanders typically maintain lower haemoglobin levels than Andeans but show:

  • higher ventilation;
  • altered blood-flow regulation;
  • efficient oxygen delivery.

This demonstrates different adaptive pathways to the same environmental stress.

Biocultural significance

High-altitude survival also depends on:

  • clothing;
  • housing;
  • diet;
  • reduced workload;
  • behavioural adaptation.

Hence:

Genetic adaptation + Developmental acclimatization + Culture = Highland adaptation

Conclusion

High-altitude populations face hypoxia, cold, dehydration and high UV exposure. Native highlanders combat low oxygen pressure through enhanced ventilation, efficient pulmonary diffusion, appropriate haemoglobin levels, improved circulation and tissue oxygen delivery. Their adaptation represents a classic example of human biological and biocultural adjustment to extreme environments.

2026 Canalization and catch-up growth. 2026 Genetic polymorphism and natural selection. 2026 Numerical chromosomal aberrations can be due to abnormalities in autosomes as well as sex chromosomes. Elaborate in terms of the effects these have on human body, giving suitable examples. 2026 Distinguishing features of nuclear and mitochondrial DNA.

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