Daniel Berehulak / Getty Images Hindu devotees bathe in the waters of Sangam, the confluence of the holy rivers Ganges, Yamuna and (mythical) Saraswati, during the Kumbh Mela in Allahabad, India, on Jan. 15, 2013

What’s billed as the largest single gathering of humanity is taking place right now in the northern Indian city of Allahabad. At the confluence of the Yamuna, Ganges and (mythical) Saraswati Rivers, as many as 100 million people will participate over the next month in an ancient Hindu festival known as the Kumbh Mela. The pilgrimage, which dates back millennia, occurs in 12-year cycles — in 2001, the Indian government estimated a staggering 70 million congregated by the Ganges’ banks to ritually bathe in its sacred waters.

News-agency photographers, of course, have a field day (or month) during the Kumbh Mela. It’s a time when India’s rising global clout and simmering social tensions take a backseat to images of ascetic sadhus — their faces doused in ash, their feral, matted hair coiled like serpents upon their heads — charging the river in religious ecstasy. Of course, it’s nothing new in India for outsiders to gawk at such “timeless” rites. Here’s a British colonial officer in the mid–19th century, who saw the Mela as proof of the need for Indians to be converted to Christianity:

Even now, multitudes of pilgrims crowd to the confluence of these sacred rivers, and every year there are some who voluntarily rush to death; and when the swollen corpse rises again to the surface; it becomes the prey of the vultures which hover round the scene of the sacrifice. Who that beholds these horrid spectacles, can forbear to desire the conversion of a people so unhappily blind to present happiness and eternal glory.

(PHOTOS: Tens of Millions Gather at India’s Maha Kumbh Mela)

Imperial hubris aside, at first glance it is difficult to understand what would tempt anybody to join such an immense throng. On certain auspicious days, as many as 10 million to 30 million people may flock to the waters of the Sangam, the meeting point of the Yamuna, the Ganges and the Saraswati. The Atlantic’s Quartz website places that sort of an event in global perspective:

Imagine the entire population of Shanghai—about 23 million—camping on a 4×8 kilometer field. Add to that mass of humanity every last man, woman and child in New York City and you’re getting closer to the Kumbh’s expected attendance. But still not quite there. The area of the mela is also on the rise: from 1,495.31 hectare and 11 sectors in 2001 to 1936.56 hectare and 14 sectors in 2013. That’s about 4,784 acres of land – about the size of Madrid’s famous Casa de Campo park.

And imagine the pollution, the press of bodies, the baseness of camping conditions, the difficulty to simply move from one site to another. Imagine too the noise generated by so many human beings just massed together in one place. By some estimates, it reaches a constant drone of over 80 decibels, prolonged exposure to which is considered hazardous to one’s hearing. My grandmother, a braver soul than me (and a native Allahabadi), went to the Kumbh Mela in 2001 and came away awed by its ceaseless din.

(PHOTOS: Holy Water: Controversy on the Ganges)

But she also came away impressed. The Kumbh Melas in Allahabad have become incredible feats of mass-scale planning, and the event in 2001 was noted for its lack of incident and the smoothness of its proceedings. Some 30,000 police officers are deployed to patrol the camp grounds; dozens of pontoon bridges spring up across the mighty rivers; the transient city that emerges is replete with cell-phone towers, makeshift hospitals, fountains and wells that pump clean drinking water, sewage facilities, a security apparatus threaded together by CCTV cameras and myriad markets and food kiosks. The scale of the operation is so unprecedented that a cross-disciplinary team of Harvard scholars, under the aegis of the university’s South Asia Institute, is attending the Mela this year in a bid to analyze the economy and logistics of what they’ve dubbed a “pop-up megacity.”

According to a separate team of academics, what was once “horrid spectacle” for outsiders is now not only instructive but also actually good for you. Based on six years of studying smaller Melas on the Ganges, a group of Indian and Western researchers have published a paper in PLOS One journal arguing that the experience of participating in such mass, collective rites has long-term benefits for the individual. Compared with a sample group not attending the festival, those who did, the study found, reported improvements both in their health and broader state of well-being. The cause for that, researchers say, is not the result of being immersed in the Ganges’ muddied waters, but the act of discovering oneself amid an endless sea of others bent on the same spiritual quest. Stephen Reicher, a psychologist at the University of St. Andrews, in Scotland, who worked on the study, writes in the Guardian:

Our analysis… shows it is the sense of intimate social relations – that we are not alone, that we can call on others, that these others form a “social safety net” for us – that creates improvements in well being once [devotees] leave the Ganges and go back to their everyday lives.

If that’s the case, then maybe the Hindu ancients — and the tens of millions journeying to the confluence of the rivers now — are onto something.

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