Anyone who’s pondered the fact that Italian tomato sauce owes a botanical debt to Central America, where the fruits first evolved, knows that foods, like humans, do travel. Many foods have traveled because intrepid humans made it their mission to seek and return with the most delicious foods around the globe; witness the introduction of Corsican lemons and Chilean avocados to American soil, thanks to explorer David Fairchild.

Other foods have crossed borders because scientists saw value in documenting botanical diversity, a la the Soviet geneticist N.I. Vavilov. And still other foods have journeyed surreptitiously, carried along by migrating birds. But the next logical line of inquiry—Which foods? And how much? And between where?—has been left to speculation.

Until now.

Researchers with the International