Howard Falcon-Lang in BBC News:
Two hundred years ago, Ascension Island was a barren volcanic edifice.
Today, its peaks are covered by lush tropical “cloud forest”.
What happened in the interim is the amazing story of how the architect of evolution, Kew Gardens and the Royal Navy conspired to build a fully functioning, but totally artificial ecosystem.
By a bizarre twist, this great imperial experiment may hold the key to the future colonisation of Mars.
The tiny tropical island of Ascension is not easy to find. It is incredibly remote, located 1,600km (1,000 miles) from the coast of Africa and 2,250km (1,400 miles) from South America.
Its existence depends entirely on what geologists call the mid-Atlantic ridge. This is a chain of underwater volcanoes formed as the ocean is wrenched apart.
However, because Ascension occupies a “hot spot” on the ridge, its volcano is especially active. A million years ago, molten magma explosively burst above the waves.
A new island was born.