Comparison of pre-conquest and contemporary Andean llama and alpaca phenotypes suggests that a breakdown in specialized breeding took place after European contact which led to the disappearance of fine fibre producing alpaca and llama breeds. The causes of this loss ultimately lie in the decimation of native Andean herds and herders during the Spanish conquest. The heterogeneous characteristics of today's animals can be attributed to extensive hybridization and a possible genetic bottle neck during the 16th century. © 1995.