India, Oct. 23 -- Sometimes small choices can end up reshaping a whole continent. The National Museum of Australia notes that on Christmas Day in 1859, Thomas Austin, a self-made man and wealthy settler, released 13 wild European rabbits on his estate in Victoria, Australia. The rabbits were let go for people to hunt for sport. By 1866, seven years after the release, hunters had shot 14,000 rabbits on the estate. The release marked the start of one of Australia's major pest problems.

A relative in England had specifically collected the rabbits and sent them to Austin. Rabbits had been introduced to Australia before; five were on the First Fleet, but they were never released into the wild. Austin's rabbits were different. They went out an...