The Columbian Exchange can be considered a bio-terrorist attack because although it brought about positive changes to American environment, the negative impact proved much greater. The Europeans carried diseases, such as smallpox and measles, which wiped out nearly 80 percent of the native population. Both sides suffered casualties as a result of this exchange, killing off entire cultures in the Americas and changing the practices in European culture. However, European causalities can not compare to the decimation in the New World. Millions suffered from the new and strange diseases, either dying from the disease or from the lack of care that was available to them. It was an outright massacre by the Europeans, although it was not intentional. The destruction of the native population led to the need of quick and cheap labor. Slavery exchange had already taken place in African by earlier civilizations, and so slavery guidelines have been established there. Europeans began to ship slaves over to the Americas, where they were put through rigorous and laborious work. Slaves came to be Africa’s main source of wealth and income. They were more abundant and less costly especially in times of dispute among African states. The treatment of these slaves in the Americas depended on where they were sent, but conditions were never humane or just no matter where they worked. As one of the most crucial of scenarios, owners of the sugar plantations of the Caribbean and Brazil believed it to be much cheaper to work their slaves to death rather than to feed and provide them with adequate shelter and clothing for them to work longer. On other plantations, owners provided these basic human needs to their slaves in order for them to nurture and provide offspring, which would further benefit the owners.