A brown bear that lay almost perfectly preserved in the frozen wilds of eastern Siberia for almost 3,500 years has undergone an autopsy by a team of scientists after it was discovered by reindeer herders on a desolate island in the Arctic.

"This find is absolutely unique: the complete carcass of an ancient brown bear," said Maxim Cheprasov, laboratory chief at the Lazarev Mammoth Museum Laboratory at the North-Eastern Federal University in Yakutsk, eastern Siberia.

The female bear was found by reindeer herders in 2020 jutting out of the permafrost on Bolshoy Lyakhovsky Island, part of the New Siberian archipelago, around 4,600 kilometres east of Moscow.

Because it was found just east of the Bolshoy Etherican River, it has been named the Etherican brown bear.

The extreme temperatures helped preserve the bear's soft tissue for 3,460 years, as well as the remains of its final meals — bird feathers and plants. The bear is described as being 1.55 metres tall and weighing nearly 78 kilograms.

"For the first time, a carcass with soft tissues has fallen into the hands of scientists, giving us the opportunity to study the internal organs and examine the brain," said Mr Cheprasov.

The scientific team in Siberia cut through the bear's tough hide, allowing scientists to examine its brain and internal organs and carry out a host of cellular, microbiological, virological and genetic studies.

They also sawed through its skull, using a vacuum cleaner to suck up the skull bone dust, before extracting its brain.

He said the bear was probably about two to three years old, and died from an injury to its spinal column.

It is, however, unclear how the bear came to be on the island, which is now divided from the mainland by a 50-kilometre strait.

It may have crossed over ice, swum over or the island might still have been part of the mainland.

The Lyakhovsky islands contain some of the richest palaeontological treasures in the world, attracting both scientists and ivory traders hunting for woolly mammoths.

Reuters