Poles Apart

PHOTO by Oleg Pashuk / RIA Novosti
The peoples of the Far North have developed unique biological mechanisms to adapt to extreme climates

The Far North is notorious for its unfriendly climate. The frost, the atmospheric pressure fluctuations, the variation in the amount of sunlight between the polar night and the polar day, the geomagnetic disturbances – all of this seriously tests the human body. So how do the people of the Arctic survive the harsh weather conditions?

The indigenous peoples of the Far North have congenital adaptive systems for coping with the physical demands of the polar climate. A mixture of physiological features known as the polar metabolic type helps Arctic residents withstand the cold, and these features make them less prone to disease. A recent project carried out from Dec. 2013 to Feb. 2014 by Russian researchers revealed some important adaptation mechanisms developed by the Evenks, one of the ethnic groups that inhabit the Arctic circle. The study was conducted during the polar night period among 180 male subjects residing in the Olenyoksky District of Yakutia, who were separated into age groups (14-17, 18-24, 25-34, 35-50, 51-64 and 65-78 years old).

As part of the study, peripheral blood tests were performed to measure the subjects’ age-dependent responses to stressors and their non-specific adaptive reactions. The researchers also monitored the subjects’ heartbeat to evaluate the response of the autonomic nervous system, or ANS, to environmental changes.

Over half of the male Evenks (54%, to be exact) were found to display high reactivity levels, with a high capacity for fast mobilization and adequate response to external stimuli. On the contrary, 30% of the subjects developed inhibitory processes, leading to slower adaptive responses. Unfavourable types of non-specific adaptive responses were identified in 14% of the Evenks, while the vast majority of the subjects displayed favourable responses. Given that 30% among the latter group also had low reactivity levels, a significant proportion of the subjects appeared to show a mismatch between the work of their biological subsystems, resulting in tension in the body’s adaptive mechanisms.

Evenks

Signs of stress were present in all the age groups to a greater or lesser extent; however, older subjects did tend to demonstrate higher stress levels as well as lower reactivity. The unfavourable adaptive processes quickly caused the body to deplete its energy resources, suppressing restorative functions and undermining the body’s ability to resist the severe environment.

Stress is known to have a lowering effect on blood alcohol levels. This has been suggested as a possible explanation for alcohol abuse and mental problems such as depressive disorders, anxiety or aggression, which are common among the population of the Arctic.

Men aged 25-34 and 51-64 years old appeared to be the ones to suffer most from the harmful impact of the polar night. They displayed an overgeneralization of excitatory processes in the ANS, which quickly drained their body of energy.

On the whole, most Arctic Evenks were found to have an elevated degree of tension in the body’s regulatory system during the polar night period. The study confirms that indigenous residents of the Far North experience considerable challenges due to the extreme environment. Their bodies’ responses display an age-related pattern, with the youngest and oldest subjects demonstrating both the highest stress levels and the lowest levels of immune system activity. People aged between 51 and 64 adapt to environmental factors by excessive stimulation of the sympathetic nervous system – the part of the ANS that is also responsible for cardiac function. The adaptive mechanisms in 25-34-year-olds, however, are largely based on energy-consuming processes.

Author: Alexander Yenikeev