Chickens were among the first domesticates introduced by Europeans to North America, where they quickly became established. Morphometric analyses of chicken remains from sites in eastern Canada and the Northeastern USA demonstrate that founding populations likely came from several different types of chicken. Comparison of these data with English medieval and post-medieval assemblages reveals that continued selection for larger body size in both populations resulted in larger chickens. However, the physical proportions of these birds remained consistent across time and space until the nineteenth century, when breeders began producing specialized laying, broiler, and show birds with exaggerated characteristics.

鸡是最早由欧洲人引入北美的家禽之一，并很快在北美建立起来。对加拿大东部和美国东北部遗址的鸡残骸进行形态测量分析表明，创始种群可能来自几种不同类型的鸡。将这些数据与英国中世纪和后中世纪组合的比较表明，在两个种群中继续选择更大的体型导致了更大的鸡。然而，这些鸟类的身体比例在时间和空间上保持一致，直到 19 世纪，当时饲养员开始生产具有夸张特征的专门产蛋、肉鸡和展示鸟类。