From Charles C. Mann’s “America, Found & Lost” (National Geographic: May 2007):
It is just possible that John Rolfe was responsible for the worms—specifically the common night crawler and the red marsh worm, creatures that did not exist in the Americas before Columbus. Rolfe was a colonist in Jamestown, Virginia, the first successful English colony in North America. Most people know him today, if they know him at all, as the man who married Pocahontas. A few history buffs understand that Rolfe was one of the primary forces behind Jamestown’s eventual success. The worms hint at a third, still more important role: Rolfe inadvertently helped unleash a convulsive and permanent change in the American landscape.
Like many young English blades, Rolfe smoked – or, as the phrase went in those days, “drank” – tobacco, a fad since the Spanish had first carried back samples of Nicotiana tabacum from the Caribbean. Indians in Virginia also drank tobacco, but it was a different species, Nicotiana rustica. Virginia leaf was awful stuff, wrote colonist William Strachey: “poor and weak and of a biting taste.” After arriving in Jamestown in 1610, Rolfe talked a shipmaster into bringing him N. tabacum seeds from Trinidad and Venezuela. Six years later Rolfe returned to England with his wife, Pocahontas, and the first major shipment of his tobacco. “Pleasant, sweet, and strong,” as Rolfe’s friend Ralph Hamor described it, Jamestown’s tobacco was a hit. By 1620 the colony exported up to 50,000 pounds (23,000 kilograms) of it – and at least six times more a decade later. Ships bellied up to Jamestown and loaded up with barrels of tobacco leaves. To balance the weight, sailors dumped out ballast, mostly stones and soil. That dirt almost certainly contained English earthworms.
…
TWO HUNDRED AND FIFTY MILLION years ago the world contained a single landmass known to scientists as Pangaea. Geologic forces broke this vast expanse into pieces, sundering Eurasia and the Americas. Over time the two halves of the world developed wildly different suites of plants and animals. Columbus’s signal accomplishment was, in the phrase of historian Alfred Crosby, to reknit the torn seams of Pangaea. After 1492, the world’s ecosystems collided and mixed as European vessels carried thousands of species to new homes across the oceans. The Columbian exchange, as Crosby called it, is why there are tomatoes in Italy, oranges in Florida, chocolates in Switzerland, and hot peppers in Thailand. It is arguably the most important event in the history of life since the death of the dinosaurs.
…
But the largest ecological impact may have been wreaked by a much smaller, seemingly benign domestic animal: the European honeybee. In early 1622, a ship arrived in Jamestown that was a living exhibit of the Columbian exchange. It was loaded with exotic entities for the colonists to experiment with: grapevine cuttings, silkworm eggs, and beehives. Most bees pollinate only a few species; they tend to be fussy about where they live. European honeybees, promiscuous beasts, reside almost anywhere and pollinate almost anything in sight. Quickly, they swarmed from their hives and set up shop throughout the Americas.