By Harold McGee
The chicken underwent more evolutionary change between 1850 and 1900 than it had in its entire lifetime as a species, and under an unusual selection pressure: the fascination of Europeans and Americans with the exotic East. A political opening between England and China brought specimens of previously unknown Chinese breeds, the large, showy Cochins, to the West. These spectacular birds, so different from the run of the barnyard, touched off a chicken-breeding craze comparable to the Dutch tulip mania of the 17th century. During this “hen fever,” as one observer of the American scene called it, poultry shows were very popular and hundreds of new breeds were developed.