When was America discovered (by humans)?
Not 1492, when Columbus sailed the ocean blue. First there were the people from eastern Asia, of course, who arrived many thousands of years ago. Lately there's some renewed debate about exactly how many thousands: the arrival date seems to keep getting pushed backward in time.
Then there were the Norse, whose arrival had been considered legendary - literally, as at least two sagas tell about it - until the rediscovery of the L'Anse aux Meadows site in Newfoundland sealed the matter. That was in 1960 but it took so long for scholarly acceptance to trickle down into textbooks that I never learned about it in school.
South Pacific islanders also discovered America long before Columbus. The proof? That all-Peruivan tuberous root, the sweet potato.
For some time, the sweet potato has been viewed as "the most convincing example of putative pre-Columbian connections between human occupants of Polynesia and South America." Linguists, for example, noticed that its Native American name is dispersed across South Pacific islands as widely as the sweet potato itself.
That sounds pretty convincing. Still, would you be entirely comfortable resting a grand theory of human exploration - which is to say, your scientific reputation - on a carbonized sweet potato?
Enter researchers from Montpellier, France, who came up with an ingenious idea for testing the theory. They conducted DNA tests on samples of sweet potatoes collected in the South Pacific by the earliest European explorers, many of whom were quite keen on botanizing.
Seeds from centuries ago have been carefully stored since the ships came sailing home, and comparing them allowed the researchers to calculate how long the strains from various islands had been growing - that is, randomly mutating - in isolation from others.
Read the article from Science via Wired, which reproduces a cool-looking graph, or from Science directly, which doesn't. Or, if you possess some method for penetrating the PNAS paywall, read the actual paper.
The bottom line: Polynesians obtained sweet potatoes from Peru centuries before Columbus.
But that understates the matter, because the Polynesians can have learned about edible roots only through contact with Peruvian Indians, and I have a hard time imagining how the contact could have been anything but non-hostile.
I mean, you wouldn't just show up on somebody's continent and start randomly munching the roots of their crops, would you? Somebody would need to show you it's food, and then convince you they're not pulling your leg. As with a shared meal.
Far from discovering the Americas, then, Columbus was late to the party, at least fourth in line.
Columbus and his men fully deserve to be remembered and celebrated. They were unimaginably brave. Like astronauts and cosmonauts, they allowed themselves to be launched into the unknown, and they did it with far less assurance of return than Yuri Gagarin or Alan Shepard. But we shouldn't forget why it was "the unknown": they were sailing from ignorance.
Western Europeans and their New World cousins like to believe they're the inheritors of the Roman Empire. But the European explorers of the late Middle Ages were the products of an entirely different culture: the triumphant one. The one that condemned itself to many centuries of ignorant barbarism by sacking Rome and cutting itself off from Byzantium.
With the technology of their ocean-going vessels and gunpowder, and their immense ignorance of the world - and their unwitting hosting of various weapons of mass destruction - Columbus's brave men were tyrannosaurs in F-14s.