Climbing the Lhotse ice wall on Mount Everest, Sameer Nicholas Patham, a mountaineer struggled to breathe, despite using supplementary oxygen. Every step in the steep ice wall — where temperatures drop to -30 Degrees Celsius and the ambient oxygen drops to 70% less than what we breathe at sea level — was torture.
But his Sherpa friends calmly climbed past him, carrying an average weight of 16kgs, with ease. “They are super humans,” recalls Sameer, who has experienced, first hand, what he describes as incredible feats of Sherpas, one of the Tibetan ethnic groups, known globally for their natural mountaineering skills.
Hostile climate, low oxygen levels and harsh terrain — people living in the Himalayas have been surviving the challenging environment for thousands of years.
Travel to Ladakh, Sikkim, Bhutan or Tibet — the Himalayan population, with their robust physical appearance and rugged lives have taught the world a thing or two about extreme survival, something that has often intrigued mountaineers and adventure seekers from all over the world.
Now, a team of Indian scientists, who set out on a mission to find out how the the ethnic Himalayan tribes have been living in extreme climatic and geographical conditions, may just have the answers.
First, the findings.
Despite the prevailing hostile climate in and around the Himalayas, there is evidence of early human settlement.
“While settling there for longer periods of time, the people in this region have acquired extraordinary way to fight back the extreme climatic conditions in form of changes (mutations) in their genome. Thus, there exist positive selections of several genes which ultimately are the drivers of adaptation in harsh environment,” explains Gyaneshwar Chaubey, known worldwide for his extraordinary work in the fields of Biological Anthropology, Medical Genetics and Forensics.
A Professor in the department of Zoology at Banaras Hindu University (BHU), Chaubey was part of the team of Scientists (from the University of Calcutta and BHU) which analysed the anthropometric and biochemical parameters of 178 individuals from the ethnic tribes living at an altitudinal range of 1467-2258 metres above sea level.
They found that populations living at high altitudes have significantly low haemoglobin and high blood pressure to cope with the extreme climate. This study was published recently in the American Journal of Human Biology.
The study covered Sherpas, Lepchas, Gorkhas, Tibetans and the Bhutia tribes, all of whom have made Himalayas their home since time immemorial. The data was statistically analyzed using analysis of variance and multiple linear regression methods.
“The adaptation due to their genomic mutations has enabled them to utilise the prevailing less atmospheric oxygen levels and cold climate. However, how these genes modulate, the phenotype still needs to be discovered,” says Chaubey.
More surprisingly, he says, the most predominant gene of this high altitude adaptation family i.e. EPAS1 introgressed to modern humans via admixture with archaic humans known as Denisovan. “Many scientists think that these Denisovans are mysterious Yeti who exist mainly in folklores and stories,” says Chaubey.
Gene from Denisovan genome to modern humans involved in adaptation to low oxygen that allows modern Tibetans and the Sherpa people to live at high altitude more comfortably than others, he says adding that the Himalayas forms a great physical barrier for migrations and plays a vital role in shaping the population dynamics not only in its vast stretch but also in nearby places.
As part of the study, the team measured 10 parameters — body weight, height, BMI, blood pressure, pulse rate, SpO2, haemoglobin, hematocrit and blood glucose levels.
On an average, Sherpas and Tibetans had mean haemoglobin content, slightly over 12 g/dl (14.9 g/dl control value) and their mean systolic and diastolic pressure was 142 mmHg (120 mmHg control value) and 94 mmHg (control value 80 mmHg) respectively. The haemoglobin content was highest among Bhutia (14.23 mmHg) followed by Lepcha (13.6 mmHg).
“Comparatively low haemoglobin in blood facilitates efficient blood circulation in the high altitude populations enabling them to utilise less oxygen more efficiently,”explains Dr Rakesh Tamang, the lead author of the study.
MOUNTAINEERS SPEAK
Describing those living up in the high altitudes as super heroes, mountaineer, Jaahnvi Sriperanbuduru, who holds the record of climbing the highest peaks of four continents by age 16, says she has personally seen men, women, children and even aged people living in extreme conditions. “As for Sherpas, their body is built so differently than anyone in the world. Their pulse can drop to the lowest number, but that's just how their body is built and is absolutely normal.”
She and her father, a doctor who have been to mountaineering expeditions together, often discuss the body structure of those living in Himalayas.
Since 1953, more than 300 climbers have died on their way to Mount Everest. A third of these succumbed due to lack of oxygen.
“Unlike Sherpas, we need to acclimatise our body to the surroundings every time we head to the high altitude environment as we come from a place with 100 per cent oxygen,” says Jaahnvi,
adding that people living in the high altitude, are born in such extreme conditions, live there and are used to doing everything on there own.
Mountaineering coach and National Adventure awardee Shekar Babu Bachinepally says he always believed that the Himalayan people have it in their DNA to survive the extreme climatic conditions and high altitudes.
“For mountaineers like me, we have to climb high altitudes gradually, allowing the body time to adjust to the decrease in oxygen. The time and the capacity of acclimatization may differ from individual to individual, but giving sufficient time for acclimatization to the lower oxygen levels is the biggest survival technique for mountaineers,” he says drawing a comparison between mountaineers and Sherpas.
The Sherpas are mostly inhabitants of high altitudes of Himalaya mainly Nepal, Tibet, Bhutan, and the Indian states of West Bengal and Sikkim.
Along with acclimatization, says Shekar, mountaineers need to drink plenty of water to prevent dehydration and altitude sickness which Himalayan people can do without. “Moreover, we also use a combination of specialized equipment, techniques, and physical & mental preparation to survive in extreme conditions found in the mountains whereas they (Sherpas) don’t,” he adds.
Sameer Nicholas, whose company Adventure Pulse specializes in exotic mountain destinations across the globe, including the Everest Base Camp in Nepal, Elbrus in Russia and Mt. Kilimanjaro in Africa, says that travelling through Ladakh, one comes across so many people living in high altitudes without any issues.
“Venturing into the remote regions of Ladakh, especially the Zanskar district, I can’t help observe the ruby red sunburnt cheeks of the toddlers, as they play in their mother’s lap, or the young children running through the village paths, where one struggles to walk,” he says adding that the harsh environment has tempered these indigenous populations to not only survive but thrive over generations.
On the other hand, tourists who take a flight into the city of Leh, immediately experience the effects of high altitude.
Veteran mountaineer Raman Chander Sood, who has has several interactions with Sherpas, Bhutias and other Himalayan people living in extremely challenging environments, feels that their capacity to climb the mountains while carrying heavy loads, effortlessly is well proven.
“I always believed that this happens because they have been born and bred in those conditions, though I knew nothing about the technical side of their blood and BP parameters until the latest discovery,” says the 70 year old, who has been a keen trekked since childhood and has climbed several peaks across the world.
The Sherpas are famous for their efficient living in high altitudes and are well known globally for their mountaineering skills. The present population size of the Sherpas in India is 16012 (Census of India, 2011)
Another prominent high-altitude population is the Tibetans. The Tibetans are mainly inhabited in Tibet Autonomous Region (TAR), the Chinese province of Gansu, Qinghai, Sichuan, Yunnan, and also in countries like India, Bhutan, and Nepal. The present population size of Tibetans in India is 182685 (Census 2011). In India, they are well scattered in West Bengal, Himachal Pradesh, Arunachal Pradesh, Ladakh, Karnataka and Uttarakhand.
The Lepchas are considered as an aboriginal tribe of the Darjeeling and Sikkim Himalayas. They call themselves “Rong Migyit” meaning the “Lepcha people”. There are 47331 Lepcha individuals in India (Census of India, 2011).
The Bhutia tribe is well scattered all over the Himalayan region. In India, they are mainly inhabitants of the state of West Bengal, Sikkim, Himachal Pradesh, Uttarakhand, and Jammu & Kashmir. Their present population size in India is 229954 (Census of India, 2011).