Animals including llamas, alpacas, and guinea pigs were domesticated there. Animals were also domesticated, including llamas, alpacas, and guinea pigs. To date, humans have domesticated goats, sheep, cattle, camels, llamas, alpacas, and pigs. Dromedary camels, bactrian camels, llamas, and alpacas are all induced ovulators. They also domesticated animals such as cuys (guinea pigs) and camelids&colon; llamas and alpacas. Indigenous Americans also domesticated some animals, such as llamas, alpacas, and guinea-pigs. Alpacas and llamas are related to the guanaco. Most animal bones found were from llamas and alpacas. The host animals may include horses, donkeys, goats, sheep, rabbits, chickens, llamas, and camels. Critics have disputed this by arguing that llamas, alpacas, and bison were domesticated. However, alpacas are often noticeably smaller than llamas. In llamas and alpacas, ejaculation occurs continuously during copulation. In the Altiplano, communities of indigenous people depend on raising camelids, especially llamas. Others soon followed, including muntjac deer, llamas, wombats and skunks. Most research on the effectiveness of guard llamas has been done with sheep.