VAID'S ICS – Best UPSC Anthropology Coaching in Delhi Since 1985

Comprehensive Classroom Course · Admissions openRegister now
+91 93113 37737
  • +91-93113 37737, +91-99999 46748
  • 73(FF), Old Rajender Nagar Market, Delhi - 110060
  • MON to SUN 9.00 am - 6.00 pm
Facebook Youtube Instagram
Menu
Enquire Now
Home/Anthropology/Mains PYQ/2021/Paper I/Human Genetics & Human Biology
UPSC MainsAnthropology Optional Paper I 2021 20 Marks Model Answer Available

Acclimatization to High Altitude and Cold Climate — 2021 Paper I

Question · 2021 · Paper I · 20 Marks

What is acclimatization ? Discuss adaptive responses to high altitude and cold climate.

Model Answer

VAID ICS

Approach

  • Demand of Question: Define acclimatization and explain human physiological, developmental and population-level responses to hypoxia and cold.
  • Structuring the Response: Concept → high-altitude responses → cold-climate responses → anthropological significance.
  • Key Dimensions to Cover: Lasker, Baker, Frisancho, Beall; ventilation, erythropoiesis, thermogenesis, vasoconstriction, Bergmann–Allen rules and cultural adaptation.

Model Answer

Introduction

Acclimatization is a reversible physiological adjustment acquired during an individual’s lifetime in response to natural environmental stress. Gabriel W. Lasker, in “Human Biological Adaptability: The Ecological Approach in Physical Anthropology” (1969), distinguished genetic adaptation, developmental adaptation and reversible acclimatization.

Adaptive Responses to High Altitude

High altitude produces hypobaric hypoxia because declining atmospheric pressure lowers the partial pressure of oxygen. Anthropological studies by Paul T. Baker, including “Human Adaptation to High Altitude” (1969), and later work among Andean populations established high altitude as a classic field of human adaptability research.

Immediate and short-term acclimatization:

  • Hyperventilation increases alveolar oxygen uptake.
  • Increased ventilation produces respiratory alkalosis; renal compensation gradually restores acid-base balance.
  • Hypoxia stimulates erythropoietin, increasing red-cell production and haemoglobin concentration.
  • Cardiovascular adjustments initially increase oxygen delivery to tissues.

Developmental responses: Individuals growing at high altitude may develop larger chest dimensions and lung capacities. A.R. Frisancho’s studies of Quechua populations demonstrated accelerated chest development under high-altitude hypoxic stress.

Genetic/population adaptation: Highland populations show different evolutionary solutions. Cynthia Beall (2007) demonstrated that Tibetans and Andeans follow distinct routes to successful oxygen delivery. Tibetans generally show stronger ventilatory responses and relatively lower haemoglobin levels, whereas Andeans characteristically rely more on elevated haemoglobin concentration.

Hypoxia → Ventilation → Erythropoiesis → Improved O₂ delivery

Adaptive Responses to Cold Climate

Cold threatens the body through excessive heat loss. Acute physiological defence involves:

  • Peripheral vasoconstriction to reduce heat loss.
  • Shivering thermogenesis through involuntary muscular activity.
  • Non-shivering thermogenesis, involving metabolic heat production, including activity of brown adipose tissue.

Repeated exposure may produce three broad patterns of cold acclimatization:

Habituation: reduced shivering, cold sensation and sympathetic response after repeated exposure.

Metabolic adjustment: increased heat production through higher thermogenesis.

Insulative adjustment: enhanced conservation of body heat through peripheral vascular responses.

At the population level, Bergmann’s Rule (1847) predicts relatively greater body mass in colder climates, while Allen’s Rule (1877) predicts shorter extremities, reducing surface area for heat loss. Inuit, Aleut and Sami populations broadly illustrate such cold-climate body proportions, although these rules are statistical tendencies rather than absolute laws.

Cold adaptation is also strongly bio-cultural: clothing, insulated shelters, fire, high-energy diets and activity patterns greatly supplement limited human physiological cold tolerance.

Conclusion

Human responses to altitude and cold demonstrate the plasticity of the human organism. As emphasised by Frisancho in Human Adaptation and Accommodation (1993), successful adaptation integrates short-term acclimatization, developmental plasticity, genetic adaptation and cultural behaviour, making environmental adaptation fundamentally bio-cultural.

2026 In what manner is our understanding of serogenetics and cytogenetics useful in reproductive biology? What are the major ethical issues involved in reproductive technology? 2026 Why the classifications of Indian populations, based on somatometric and somatoscopic characteristics failed to develop a common understanding of the population diversity? 2026 Canalization and catch-up growth. 2026 Genetic polymorphism and natural selection.

Want feedback on your answer?

Join the Anthropology workshop or get structured answer-writing guidance from VAID ICS.

Join Workshop Contact VAID ICS

UPSC Anthropology Optional 2021 — Paper I

28 questions

1(a) Animism and Deep Ecology

10 Marks150 words
Syllabus: Paper I > 5. Religion > Forms of religion > Animism
2021Paper IAnthropology of ReligionModel answer available

5(d) Descent Groups

10 Marks150 words
Syllabus: Paper I > 2.5 Kinship > Descent groups
2021Paper IKinshipModel answer available

5(a) Human adolescent growth spurt

10 Marks150 words
Syllabus: Paper I > 10. Human growth and development > Stages of growth > Adolescence
2021Paper IHuman Genetics & Human BiologyModel answer available

5(e) Modes of Subsistence

10 Marks150 words
Syllabus: Paper I > 3. Economic Organization > Modes of subsistence
2021Paper IEconomic & Political AnthropologyModel answer available

5(b) The losses and gains of erect posture

10 Marks150 words
Syllabus: Paper I > 1.5 Characteristics of Primates > Skeletal changes due to erect posture
2021Paper IHuman Evolution & PrimatologyModel answer available

1(e) Thermoluminescence (TL) dating

10 Marks150 words
Syllabus: Paper I > 1.8(a) Chronology: relative and absolute dating methods
2021Paper IPrehistoric ArchaeologyModel answer available