“We may think of volcanic islands like Ascension as unusual because their recent origin and remoteness mean their ecosystems are made up of a motley crew of mariner migrants. But much of the world is like that. Nature is constantly in flux, and few ecosystems go back very far. Only ten thousand years ago, much of Europe and North America were covered in thick ice. All soil had been scraped away and with it most forms of life. Everything we see today in these former glaciated zones has either returned or arrived for the first time since the ice retreated. Looked at from this perspective, the spread of alien species today is merely a continuation of a natural process of the colonization begun when the ice retreated. A broad time horizon shows there is no such thing as a native species. All lodgings are temporary and all ecosystems in a constant flux, the victims of circumstance and geological accident. As the pioneer British ecologist Charles Elton argued, “Were it not for the ice age, we [in Britain] should probably have wonderful mixed forests with wild magnolias and laurels and epiphytic orchids, such as . . . in China.” Ice AgeLaurel ForestsNaturalized Species Book:The New Wild: Why Invasive Species Will Be Nature's Salvation Source: The New Wild: Why Invasive Species Will Be Nature's Salvation