Superhuman porters
It has always been believed that the porters of Nepal are the strongest load-carriers on Earth. With a strap that goes across their foreheads to carry the weight, they lean forwards to balance their wickerwork baskets piled high with goods. They grunt and heave their way up and down the Himalayan trails for days on end. It had seemed superhuman, it apparently is.
The load-bearing capacity of the Nepali highlander has been recorded by more than one scientific team on the Everest trail up to the Sherpa market town of Namche Bazaar. The teams have studied the rugged men and women of Nepal's midhills who routinely carry loads that greatly exceed their own body weight to altitudes that would give any seasoned trekker pause. In a new study published in the academic journal Science, physiologist Norman Heglund and his colleagues from the Universite Catholique de Louvain in Belgium set out to determine exactly how the porters are able to carry so much.
Setting up a field research station near Namche Bajaar (height 3500 metres), the team examined over 100 male and female porters, chosen at random. The scientists determined the body weight and the weight of the loads carried by the selected porters, whose ages ranged from 11 to 68. Special masks were also used to monitor the oxygen intake of working porters as they climbed to reach the weekly Saturday bazaar at Namche.
On a single day before the Saturday market, the study counted more than 642 porters hauling an estimated 30 tons of freight up the steep climb from the Dudh Kosi valley. Most of these porters had traveled ten or more days by foot from the roadhead town of Jiri – logging more than 8000 metres of climbing and 6300 metres of descent. The average male porter on this route carried a load that amounted to 96 percent of his body weight, and female porters carried roughly 66 percent. The largest load observed was a whopping 183 percent of the carrier's body weight.
(An earlier study by scholar Nancy J. Malville Published in The American Journal of Human Biology in 2001 studied male porters on the same trade route, but closer to Jiri. This study found the average load to be approximately 150 percent of the carrier's body weight. One explanation for the discrepancy with the Science report may be that the porters sell goods to households and stores en route to Namche, thus shedding weight as they proceed.)
Portering populations across the world use their heads to support their burdens, but none carry loads as heavy as those carried by the Nepalis. The source of the incredible strength of these porters is still unclear, but the Science article speculates that it may be tied to their short stature combined with their painstakingly slow walking pace and frequent rests. The researchers noted that the porters were extremely efficient workers – the average tourist trekker expends the same amount of energy to carry 15 percent of her body weight as a porter carrying 100 percent.
The sheer strength of these men and women and the astounding weight of their burdens is also a testament to the harsh realities faced by Nepal's poorest citizens. As the economy of the country continues to plummet, fuelled by the growing political instability and the near-collapse of the tourism industry, one wonders where the porters will turn next. Once the demand for their goods decreases, they will find themselves with even fewer options for survival. These men and women have already pushed the limits of human strength and endurance, and now they are being burdened even more.