How do species split — and what if two people arrive at once?

That time, that place

In February 1858, on the island of Ternate in the Malay archipelago, Alfred Russel Wallace lay ill with fever. He made his living collecting specimens and selling them.

Lying there, he wrote, the answer to how species change came to him. Within three days he had written it up and posted it.

Why this question

The trouble was where he sent it. He sent it to Charles Darwin — a correspondent, and someone whose opinion he valued.

Darwin read it and saw his own twenty-years-delayed work laid out. He wrote to a friend that whatever originality he had was smashed.

What was found

Lyell and Hooker arranged a compromise: that July the Linnean Society heard Wallace's paper alongside extracts from Darwin's earlier writings. Neither man was present. Wallace was still in Southeast Asia and had not been consulted.

The next year Darwin published the Origin — a book heavy with evidence, and it was the book that changed the world.

Wallace deferred to Darwin for the rest of his life, and even titled one of his own books Darwinism. He also found the boundary line across which animal life changes abruptly, and it is still called the Wallace Line.