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Home/Anthropology/Mains PYQ/2015/Paper I/Human Genetics & Human Biology
UPSC MainsAnthropology Optional Paper I 2015 15 Marks Model Answer Available

Physiological Responses and Acclimatization to Cold Climate — 2015 Paper I

Question · 2015 · Paper I · 15 Marks

Critically examine the physiological responses and acclimatization to cold climate in Man.

Model Answer

VAID ICS

Approach

  • Demand of Question: Examine immediate physiological responses to cold and longer-term acclimatization, while distinguishing these from inherited population-level adaptations.
  • Structuring the Response: Discuss heat conservation and heat production, followed by acclimatization patterns and comparative population examples.
  • Key Dimensions to Cover: Vasoconstriction, shivering, thermogenesis, basal metabolism, peripheral temperature, cold-induced vasodilation, body form, Inuit and acclimatization.

Model Answer

Introduction: Humans maintain a relatively constant core temperature despite environmental variation. Exposure to cold activates physiological mechanisms aimed at reducing heat loss and increasing heat production. Repeated exposure may produce acclimatization, while long-term population differences may also reflect developmental and genetic adaptation.

Immediate physiological responses

  1. Peripheral vasoconstriction

Cold stimulates narrowing of blood vessels in the:

  • skin;
  • hands;
  • feet.

This reduces warm blood flow to the body surface and conserves core heat.

Thus:

Cold exposure → Vasoconstriction → Reduced peripheral heat loss

However, prolonged vasoconstriction increases the risk of tissue cooling and frost injury.

  1. Shivering thermogenesis

Involuntary contraction of skeletal muscles produces additional metabolic heat.

Muscular activity → Increased metabolism → Heat production

Shivering is particularly important during acute cold stress but is energetically expensive.

  1. Non-shivering thermogenesis

Cold can also increase heat production without visible muscular contraction through:

  • sympathetic activity;
  • metabolic responses;
  • brown adipose tissue, especially important in infants and also functional to varying degrees in adults.
  1. Increased metabolic rate

Severe or repeated cold exposure may increase energy expenditure and metabolic heat production.

Adequate caloric intake therefore becomes particularly important in cold environments.

  1. Piloerection

Hair follicles contract and hairs stand upright. In humans this has little thermoregulatory value because of sparse body hair.

Peripheral adaptations

Cold-induced vasodilation

During prolonged cold exposure, peripheral blood vessels may periodically dilate after initial constriction.

This phenomenon, sometimes called the “hunting response”, provides intermittent warm blood flow to extremities and may reduce cold injury.

Acclimatization to cold

Unlike heat acclimatization, cold acclimatization is relatively variable and may take different forms.

  1. Metabolic acclimatization

Repeated cold exposure may produce:

  • increased basal or resting metabolic response;
  • enhanced thermogenesis.

This raises internal heat production.

  1. Insulative acclimatization

Some individuals develop greater tolerance for lower skin temperatures while maintaining core temperature.

This involves:

  • stronger peripheral vasoconstriction;
  • reduced skin blood flow;
  • greater thermal gradient between core and skin.
  1. Habituation

Repeated mild cold exposure can reduce:

  • shivering;
  • subjective discomfort;
  • stress responses.

This represents altered physiological responsiveness rather than necessarily increased heat production.

Anthropological examples

Populations inhabiting cold environments illustrate the interaction of physiology, morphology and culture.

For example, Arctic populations such as the Inuit historically relied heavily on:

  • high-energy diets;
  • insulated clothing;
  • shelters;
  • behavioural regulation.

Cold adaptation is therefore strongly biocultural.

Morphological patterns broadly consistent with Bergmann’s and Allen’s rules—relatively compact bodies and shorter extremities in cold climates—can reduce surface-area-to-volume ratio and heat loss, though human variation is influenced by multiple factors.

Critical examination

Cold adaptation cannot be explained by physiology alone because:

  1. clothing and shelter greatly reduce selection pressure;
  2. nutritional status alters heat production;
  3. body composition affects insulation;
  4. age, sex and health influence tolerance;
  5. acclimatization differs from genetically inherited adaptation.

Therefore:

Cold survival = Physiology + Morphology + Behaviour + Technology

Conclusion

Human response to cold involves vasoconstriction, shivering and metabolic thermogenesis, while repeated exposure may lead to metabolic, insulative or habituation-type acclimatization. Yet the exceptional human ability to inhabit extreme cold is ultimately a biocultural achievement, combining physiological flexibility with clothing, shelter, diet and social behaviour.

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UPSC Anthropology Optional 2015 — Paper I

28 questions

1(a) Archaeological Anthropology.

10 Marks150 words
Syllabus: Paper I > 1.3 Main branches of Anthropology > Archaeological Anthropology
2015Paper IFoundations of AnthropologyModel answer available

5(e) DNA technology in Medicine.

10 Marks150 words
Syllabus: Paper I > 12. Applications of Anthropology > DNA technology in diseases and medicine
2015Paper IApplied & Forensic AnthropologyModel answer available

5(b) Down's Syndrome.

10 Marks150 words
Syllabus: Paper I > 9.4(c) Autosomal aberrations > Down syndrome
2015Paper IHuman Genetics & Human BiologyModel answer available

1(e) Historical Particularism.

10 Marks150 words
Syllabus: Paper I > 6. Anthropological Theories > Historical Particularism (Boas)
2015Paper IAnthropological TheoriesModel answer available

1(d) Horticulture.

10 Marks150 words
Syllabus: Paper I > 3. Economic Organization > Modes of subsistence > Horticulture
2015Paper IEconomic & Political AnthropologyModel answer available

1(c) Incest Taboos.

10 Marks150 words
Syllabus: Paper I > 2.3 Marriage > Rules of marriage > Incest taboo
2015Paper IMarriage & FamilyModel answer available

5(c) Longitudinal method of studying growth.

10 Marks150 words
Syllabus: Paper I > 10. Human growth and development > Methodologies for growth studies > Longitudinal method
2015Paper IHuman Genetics & Human BiologyModel answer available

5(d) Menopause and its impact.

10 Marks150 words
Syllabus: Paper I > 11.1 Relevance of menarche, menopause and other bio-events to fertility
2015Paper IHuman Genetics & Human BiologyModel answer available

5(a) Palaeolithic culture.

10 Marks150 words
Syllabus: Paper I > 1.8(b) Cultural Evolution: broad outlines of prehistoric cultures > Palaeolithic
2015Paper IPrehistoric ArchaeologyModel answer available

1(b) Society and Culture.

10 Marks150 words
Syllabus: Paper I > 2.2 The Nature of Society > Society and culture
2015Paper ICulture & SocietyModel answer available