For centuries, Arctic soldiers and explorers have grown beards as a symbol of endurance against extreme cold. But beyond tradition or convenience, can facial hair actually provide a thermoregulatory advantage? 

A recent study published in Military Medicine (Potter et al., 2025) addressed this question scientifically, using mathematical and biophysical models to evaluate whether beards offer real protection against thermal stress and frostbite in polar environments.

Study Design

Researchers from the U.S. Army Research Institute of Environmental Medicine (USARIEM) used validated predictive models, including the Cold Weather Ensemble Decision Aid (CoWEDA) and Heat Strain Decision Aid (HSDA) to simulate the thermal responses of a standard male soldier with different beard levels (from clean-shaven to full beard).

Three environmental conditions were tested:

• Mild heat stress: 24 °C, 60% relative humidity
• Cold stress: −24 °C, 70% humidityExtreme cold: −45 °C, 75% humidity

The goal was to compare core and skin temperature changes and estimate the time until risk thresholds for hypothermia or facial frostbite were reached.

Main Findings

No effect on core temperature:

• Facial hair did not significantly influence overall core temperature regulation, even under severe cold exposure.

Protection against frostbite:

• Finite element modeling showed that dense beards act as localized insulation, reducing heat loss from the cheeks, chin, and upper lip.
• Practically, full beards delayed the drop in facial skin temperature to frostbite-risk levels by up to 1,100 minutes compared to clean-shaven conditions.

Additional protection beyond clothing:

• Even when wearing a standard military balaclava, beards added extra thermal resistance, lowering the likelihood of facial cold injury.

Interpretation and Relevance

While beards do not change whole-body thermoregulation, they do provide localized protection against cold injury, functioning as a natural micro-insulator. For soldiers or explorers operating in Arctic environments, this could mean fewer frostbite incidents and enhanced operational performance in extreme conditions.

From a biomedical perspective, this study exemplifies how thermal modeling and thermography-based analysis can quantify physiological advantages in unique scenarios from military performance to evolutionary adaptations of human hair.

Conclusion

• Beards may not keep the body warmer, but they protect the face.
• This research demonstrates that even everyday human traits can have measurable physiological benefits in extreme climates.
• It’s another fascinating example of how thermal physiology and its study through modeling and infrared analysis, continues to reveal nature’s ingenious strategies for human adaptation to the cold.

Referencia

Potter, A. W., Jacques, J. I., Poley-Bogan, M. M., Chapman, C. L., & Friedl, K. E. (2025). Does Facial Hair Provide Significant Thermoregulatory Advantage and Protection in the Arctic? A Case for Bearded Arctic Warriors. Military Medicine, usaf425.