As glaciers and ice patches melt, they reveal untold stories of human skill, adventure, faith – and deadly conflict.

Some 5,000 years ago, a tattooed man in his 40s, with brown eyes and thinning black hair, climbed a steep mountain in the Ötztal Alps, on the border between what is now Italy and Austria, to a mountain ridge more than 3,000m (9,800ft) above sea level. He was wearing a striped goat-fur coat, a bear-fur cap, and sturdy shoes with bear-leather soles, and he seemed to be in a rush. Although he was genetically predisposed to obesity, his active lifestyle had generally kept him fit and muscular. He had some health issues – stomach problems, knee issues – but that did not stop him. Nor did his extraordinary amount of gear, some incomplete, as if packed in a hurry: unfinished bow and arrows, a precious copper axe, medicinal mushrooms, and even two portable stoves made from birch bark.

He was about to cross the high ridge, perhaps hoping for safety on the other side, when an arrow hit his shoulder, severed an artery, and killed him. Snow and ice covered his body and belongings. He lay there, undetected, for thousands of years.

Elsewhere in the Alps, other bodies and belongings were also frozen in the ice for centuries, or even millennia. But a few decades ago, they began to emerge. Glaciers retreating at an ever-faster pace revealed the eerie, sometimes grisly remains, giving rise to a new scientific field: glacial archaeology, the study of ancient finds from melting glaciers. They present a surprisingly detailed and unexpectedly long timeline of adventure, innovation and danger in the high mountains."There've always been individual cases of bodies or objects emerging from the ice. Glaciers swallow people and things, and at some point, spit them out again," since the ice masses move, says Thomas Reitmaier, director of the archaeological service of the Canton of Grisons in Switzerland.There is even an Alpine German word for the process of things emerging from glaciers: "ausgeapert", meaning something is exposed by melting snow or ice. However, as global warming and record hot summers have sped up glacier loss, the melting ice has exposed an unprecedented, huge range of archaeological finds, Reitmaier says – sometimes baring thousands of years of history, all at once.
The discoveries show the human ingenuity it took to trudge over Alpine ridges and passes, to trade, to flee, to hunt, to herd, or to conquer. They include many technical innovations – such as the world's oldest snow shoe, dating from almost 6,000 years ago – as well as traces of ancient spiritual practices. Nervous Romans, who feared rockfall and avalanches, sacrificed coins to various mountain gods, before attempting dangerous Alpine crossings as they expanded their empire across Europe.Some of the most poignant and mysterious discoveries are not even that old. In the 17th Century a woman in her 20s, dressed in a man's coat and mismatched shoes, tried to cross a glacier in Switzerland. She carried with her a wooden bowl, a wooden spoon, and a rosary. She died – of a fall, perhaps – and, like the fugitive man thousands of years before her, was covered by snow and ice until she emerged in the late 1980s.

Cracking an ice mummy's secrets

Perhaps surprisingly, the discoveries also suggest that our most popular Alpine travel routes didn't change much for thousands of years. In 2003, a then-record hot summer laid bare the vast hidden history of the Schnidejoch ridge in Switzerland, Reitmaier says. "You have a continual line of objects stretching from 4800BC, through the Middle Ages, and up to the present day," he says. "Whenever that pass was open, humans crossed it, and they lost things, or they died and left things behind." It was only with the advent of roads, railroads and tunnels that these passes lost their crucial importance for getting us from one place to the other, he says.

The best-known, and most intensively studied, of these finds, is the 5,000-year-old murdered Tyrolean Iceman mentioned earlier, also known as Ötzi, after the Ötztal Alps where he was found. Conserved by the ice, he was found in 1991, in the relatively early days of the glaciers' retreat.

"Before Ötzi's discovery, archaeologists generally assumed that humans didn't visit or cross over the high mountains in the distant past," because the terrain was just too difficult, says Andreas Putzer. He is an archaeologist and curator at the South Tyrol Museum of Archaeology in Bolzano, Italy, where the ice mummy is kept. "But Ötzi taught us that humans did go up there, and that really started the archaeological research in the high mountains here in the Alps," he adds.

Decades of research on Ötzi and his belongings have brought an entire world back to life. Scientists have discovered which plants and animals he gathered, farmed and hunted. They've traced the long migration of his ancestors from Anatolia (in modern-day Turkey) to Europe, and mapped his farming community's far-flung trade network. He lived at a time when people in the area already lived in villages in the valleys, and farmed there, says Putzer, but some also still roamed widely to hunt.