The most significant impact of Columbus and other Europeans' arrival in the Americas is the exchange of plants, animals and infectious diseases between the two continents.  With the so called Columbian Exchange some very important domestic animals, such as cattle, chicken, goat, horse, pig and sheep were brought to the Americas.  Important food sources such as wheat, barley, rice, rye, sugar, carrots, apples, peach and pears were introduced in America.  While Europeans killed many American natives, the vast numbers, up to 70% – 80%, were killed by Euro-Asian diseases such as smallpox, influenza, typhoid and cholera.  The Americas did not have a domesticated beast of burden the closest animal was the alpaca.  The most important plants and animals from the Americas were corn, potato, peanut, tomato and tobacco.  It is believed syphilis originated in the Americas.