Bones found in a cave in County Waterford in 1928 indicate that the first Irishmen may have died before 9000 bc. But the evidence is unreliable, and in any case they would not have survived the last cold cycle of the Ice Age around 7000 bc. The first significant human habitation dates from the middle of the seventh millennium bc. In the previous twenty-five thousand years a variety of animal life had flourished, notably the giant Irish elk with antlers spanning up to 10 feet; great hairy mammoths, hyenas, wolves and foxes. As temperatures changed, Ireland variously experienced tropical forests, tundra and open vegetation. The landscape had been formed earlier still. The Mourne Mountains and other famous landforms were created some 75 million years ago as molten lava cooled. Drumlins and deep valleys such as the Gap of Dunloe were sculpted and gouged by the gigantic force of ice two hundred thousand years ago.

About nine thousand years ago, as the world’s warming climate melted the ice cover, sea levels rose, and Ireland lost its land link with Britain and became an island on the north-western corner of the European continental shelf, separated from her neighbours by shallow seas. A fall of 350 feet (106 metres) in sea level would once again connect south-east Ireland to Wales, while a fall of about 600 feet (182 metres) would lay bare the sea floor to France as well as the continental shelf 150 miles out into the Atlantic, west of the provinces of Munster and Connaught. Britain retained her land connections with the European mainland across the southern reaches of the North Sea to Belgium, the Netherlands and north-western Germany far longer. This explains why Britain, unlike Ireland, has snakes: by the time they reached western Britain after the Ice Age, Ireland was already an island (although legend has it instead that Saint Patrick, Ireland’s patron saint, banished the reptiles).