By 1999, the practice had grown to the point that Arizona, Colorado, Maine, Nebraska, Nevada, Rhode Island, and Virginia kept between five and eight per cent of their prison population in isolation, and, by 2003, New York had joined them as well.

NEWYORKER: Hellhole

One population of mammoths lived on in isolation on Russia's remote Wrangel Island until about 5, 000 years ago.

BBC: The mammoth's trunk and eyes are still intact

Its isolation has led to a unique geography and animal population, including the lemur, which took a star role in the 2005 animated Hollywood movie named after the island.

BBC: Pupils met the delegation from the Madagascan embassy

It is based on a piece of evolutionary theory called the founder effect, which shows how the isolation of small populations from larger ones can accelerate evolutionary change, because a small population's average characteristics are likely to differ from those of the larger group from which it is drawn.

ECONOMIST: The proper study of mankind