The 21st-century answer to this 18th-century riddle is that a species is what a taxonomist says it is.

ECONOMIST: Species inflation

"People have biases towards species that are glamorous, " said Dr. Ernie Small, author of the study and taxonomist for Agriculture Canada.

CNN: Beauty trumps beast in conservation efforts

As the group walked back to camp, Aaron Davis, a taxonomist at the Royal Botanical Gardens in Kew, England, saw a small coffee plant unlike the others.

WSJ: The Indiana Jones of Coffee

But after four days of hiking on this plateau west of Ethiopia, Mr. Schilling's 15-member expedition which included a coffee taxonomist, a Green Mountain Coffee Roasters Inc.

WSJ: The Indiana Jones of Coffee