A rare fungus some are calling Indian Viagra is starting to transform local economies in the Himalayas. But some of those harvesting it are now having to arm themselves to protect what has become a valuable cash crop.
There is a fungus that attacks caterpillars in the Indian Himalayas. People in north India call it kira jari. In neighbouring Tibet it is known as yarsagumba.
The fungus mummifies its prey and then grows out of the top of the dead caterpillar's head. It appears above ground just as the snow melts in May or June.
In China, kira jari is used as an aphrodisiac. Athletes have used it as a performance-enhancing drug. For villagers in the Indian Himalayas it is a source of income.
During the last five years they have begun to collect the caterpillar fungus and sell it to local traders. These middlemen, in turn, sell the fungi to businesspeople in Delhi and it travels on from there to Nepal and China.
When sold in the village, a single fungus fetches 150 Indian rupees (about £2 or $3) - more than the daily wage of a manual labourer.
Some people are able to collect 40 in a single day. So the search for caterpillar fungus has come to resemble a type of Himalayan gold rush.
I have spent the past few months in the Indian Himalayas doing research on youth and social change. I lived in the village of Bemni, located at about 10,000 feet (3,000m) near the Indian border with Tibet.
Much of our time was spent trying to understand the changing economy of the village, and kira jari featured heavily in our interviews.
Take Prem Singh, a 24-year-old man in the village known for his restless energy and appetite for hard work.
Prem spent the first two weeks of May in high altitude snowfields collecting kira jari. He went on his own, carrying rice, wheat and daal on his back, camping in a cave on the way, and eventually pitching camp 5,000 metres up. He found nothing during the first three days.
But then his luck changed. He returned to Bemni with 200 fungi stuffed into old sweet jars. He is using his earnings to construct a new house, an impressive two-storey structure built out of local stone.
Kira jari, and the money it earns, is big news for Bemni. Young men have generally been looking outside the village for opportunities to make money in cities down in the plains. They have worked in hotels, in the army, and in some of the new service industries emerging in urban India.
Kira jari is reversing this process somewhat. Since 2007, when villagers learnt about the fungus, vast numbers now head not to the big cities but to the high altitude meadows.
People joke that the meadows - formerly the preserve of intrepid goatherds - have become small towns of tents, stoves, and clothes' lines. As Prem told us, "Why would I migrate to Delhi to work in a hotel when I can earn in two weeks what I'd make in Delhi in two years?"
But there is a dark side to fungus collection, too.
Some villagers return with nothing to show for their weeks in high altitude snow fields. Many fall ill. Searching for the fungus involves lying on your front, elbows dug into the scree and snow, scouring the ground in front of you for nothing larger than the stalk of an apple. It is freezing cold, there is a howling wind, and your lungs ache.
People often return to the village with snow-blindness, painful joints, and problems breathing. One person died recently as a result of the altitude. Another man fell into an ice crevasse and was only rescued by villagers 13 days later - he had lived on drips from the glacier. (Apparently he is back collecting kira jari this year).
The fungus business is also generating rivalries. There are two villages that are at loggerheads over access to a high-altitude meadow where kira jari is especially abundant. They have to carry guns on their trips for the fungus.
There are other risks, too. It is legal to collect the fungus but not legal to sell it.
Two years ago, a confidence trickster arrived in Bemni and promised people he could get a very good price for their crop. He disappeared with people's fungi and has never returned. Because kira jari is part of the black market, the villagers could not complain.
Last year young men from the village tried to sell their fungi in a local town. Someone in the village tipped off the local police who intercepted the young men on the road and seized the entire fungus crop.
Imagine the heartbreak as they trooped back to the village. The men had nothing to show for weeks in the bitter cold, while the police no doubt profited from their booty.
But people seem to take these risks in their stride. As Prem said to us, "You have got your risky work and your safe work. Kira jari is the risk, local manual labour is the safe option."
For the time being, India's home-grown version of Viagra has become a decent gamble.
And no, I haven't tried it.
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