Long before written history, when the sea had not yet swallowed the land between Wales and Ireland, human beings followed animals and instinct across a frozen corridor into a world that would one day be called Ireland. A new discovery of cave art in south-west Ireland, dated to at least 15,000 years ago, quietly rewrites the oldest chapter of human settlement on the island — reminding us that the boundaries we take as permanent were once merely temporary, and that our ancestors were far more restless and resourceful than we had assumed.