1. The Columbian Exchange

2. Before 1492 Two very different ecosystems
Two sets of culturally diverse peoples
Before Columbus crossed the Atlantic, the Eastern Hemisphere (that is Europe, Africa and Asia) and the Western Hemisphere (that is the Americas) were two very different ecosystems. These ecosystems had been developing in biological isolation for thousand and thousand of years. This meant that there were two different disease pools and two sets of flora and fauna, as well as two sets of culturally diverse peoples.
Two sets of flora and fauna
Two different disease pools

3. -- Christopher Columbus
“...all the trees were as different from ours as day from night, and so the fruits, the herbage, the rocks, and all things.”
-- Christopher Columbus
The differences between the two hemispheres was often noted by those who were present at the time when Europeans were making their first incursions into the Americas.
*      Many Native Americans upon seeing Europeans and their animals for the first time were so shocked at what they saw that they did not know what to make of the invaders. Some thought the Europeans were gods, and when they saw men on horseback they were not sure if they were looking at two animals or one.
*      Europeans were equally impressed by the differences. Christopher Columbus wrote that “all the trees were as different from ours as day from night, and so the fruits, the herbage, the rocks, and all things.”
*      A Frenchman in Brazil in the 16th century wrote that America is so truly “different from Europe, Asia and Africa in the living habits of its people, the forms of its animals, and, in general, in that which the earth produces, that it can well be called the new world….”

4. Two biological ecosystems interchanged to create a new world ecology.
Two Biological Ecosystems Merge To Create A New World Ecology
When Christopher Columbus brought these two hemispheres (these two very different worlds) in contact with one another by crossing the Atlantic in 1492, he effectively brought together two biological ecosystems which then interchanged over the years to create a new world ecology. The development of this intermixed world ecology had profound consequences for humans.

5. According to historian Alfred Crosby, the exchange of plants, animals and pathogens between the two hemispheres was biologically “the most spectacular thing that has ever happened to humans," and he coined the phenomenon the Columbian Exchange.

6. An Exchange of Pathogens
There have been both negative and positive effects from the Columbian Exchange, but initially for Native Americans the consequences were devastating. By the time Columbus set sail, the people of the Old World held the distinction of being thoroughly diseased. By domesticating pigs, horses, sheep and cattle, they had infected themselves with a wide array of pathogens. And through centuries of war, exploration and city building, they had kept those agents in constant circulation. Virtually any European who crossed the Atlantic during the 16th century had battled such illnesses as smallpox and measles during childhood and emerged fully immune.
The smallpox virus

7. A Demographic Collapse
There have been both negative and positive effects from the Columbian Exchange, but initially for Native Americans the consequences were devastating. By the time Columbus set sail, the people of the Old World held the distinction of being thoroughly diseased. By domesticating pigs, horses, sheep and cattle, they had infected themselves with a wide array of pathogens. And through centuries of war, exploration and city building, they had kept those agents in constant circulation. Virtually any European who crossed the Atlantic during the 16th century had battled such illnesses as smallpox and measles during childhood and emerged fully immune.
Some European diseases introduced to the New World: smallpox, mumps measles, whooping cough, cholera, gonorrhea, yellow fever, influenza.
Aztecs afflicted with Smallpox
In Mexico alone, the native population fell from roughly 30 million in 1519 to only 3 million in 1568.
Modern-day victims of smallpox

8. Livestock
With the possible exception of syphilis, the great germ migration was largely a one-way affair. This was also the case with most livestock. The first contingent of horses, cattle, chickens, dogs, sheep and goats arrived with Columbus on the second voyage in The animals, preyed upon by few or no American predators, troubled by few or no American diseases, and left to feed freely upon the rich grasses, roots and wild fruits of the New World, reproduced rapidly.

9. A Plague of Sheep
Their numbers increased so rapidly, in fact, that doubtlessly they had much to do with the extinction of certain plants, animals, and even the Native Americans themselves, whose gardens they often trampled upon. Especially impressive was the explosive growth of herds of cattle and horses on the vast open plains of the Americas (North America, Llanos, Pampas).

10. Chickens and Eggs
Although at first harmed by the invasion of freely roaming domesticated animals, those Native Americans who survived, along with the rest of an increasingly ethnically diverse American population, grew to appreciate the domesticated animals imported by Europeans. Cattle sheep, pigs and goats provided Americans with the means to do what was only meagerly possible before 1492: turn grass, which humans cannot eat, into meat and milk. The coming of the Europeans and their animals created a colossal increase in the quantity of animal protein available to people in America.
The Spanish chronicler Antonio de Herrera tells of a wise Indian who, when asked to name the most important things he and his fellows had received from the Spaniards, put chicken eggs at the top of his list, because they were plentiful, “fresh every day, and good cooked or not cooked for young and old.”

11. The Cowboys of the Americas
Vaquero
Gaucho
Cowboy
Llanero
Horses were valued for the many tasks, but especially for transportation across the vast spaces of the American continents. Donkeys, oxen and mules were used as pack animals and provided much of the muscle with which the exploitation of America was undertaken. The hides of all these animals provided an important raw material for producing all sorts of useful things made from leather, and they became so abundant in the New World that soon American hides were being exported to Europe in large quantities.

12. The greatest impact of the Columbian Exchange was the exchange of different food crops.
Sweet Potatos
Potatos
Cassava
Wheat
The greatest impact of the Columbian Exchange, however, was the exchange of different food crops. From the New World the Old World received maize, potatoes, sweet potatoes, squash, tomatoes, peanuts, manioc, cacao, peppers, and most types of beans among other things. All of these were unknown in the Old World before 1492.
The New World in return received many new foods from the Old World. In addition to the previously mentioned domesticated animals, the New World received rice, bananas, wheat, rye, barely, sugar and coffee, among other things.

13. The Exchange of Plants and Animals
Originally from the Western Hemisphere
Potato
Maize (corn)
Manioc (cassava, tapioca)
Sweet potato
Tomato
Cacao (chocolate)
Squash
Chili peppers
Pumpkin
Papaya
Guava
Tobacco
Avocado
Pineapple
Beans (most varieties, including phaseolus vulgaris)
Peanuts
Certain cottons
Rubber
Turkeys
Originally from the Eastern Hemisphere
Sugar
Olive oil
Various grains (Wheat, rice, rye, barley, oats)
Grapes
Coffee
Horses
Cattle
Pigs
Goats
Sheep
Chickens
Various fruit trees (pear, apple, peach, orange, lemon, pomegranate, fig, banana)
Chick peas
Melons
Radishes
A wide variety of weeds and grasses
Cauliflower
Cabbage
The New World in return received many new foods from the Old World. In addition to the previously mentioned domesticated animals, the New World received rice, bananas, wheat, rye, barely, sugar and coffee, among other things.
What is your favorite food? (Try to answer where it came from. Would it have been available to you if you were a European or a Native American before 1492?)

14. An Increase in Food Supply Helped Populations to Rise
The eventual result of all the exchanging of different food crops was a dramatic increase in food supply, which in turn caused a rise in population. How and why did this happen? An entirely new food plant or set of food plants permits the utilization of soils and seasons that have previously gone unused, thus causing a real jump in food production and, therefore, population.

15. Some Tropical Plants from the Old World
Some Tropical Plants from the New World
In the Americas maize and manioc are amazingly adaptable plants, but neither grow well in swampy soils. In the swamps of the hot American lowlands, Old World rice produces greater yields than any pre-Columbian grain. In addition to rice, the dwellers of the hot, wet lowlands also received bananas, mangos and several other food plants from the Old World, [namely Africa]

16. Maize/Corn
Millions of Southern Europeans and African had their lives transformed by maize, which prospers in areas too dry for rice and too wet for wheat. Asia was also affected. In the course of the eighteenth century, China more than doubled in population due in part to new American food crops.

17. Sugar, Tobacco and Slavery
On the other side of the Atlantic, another imported crop had negative social and demographic consequences that contributed to much human suffering. Sugar was one of the first Old World plants brought to the Americas, where it thrived in the tropical climate of the Caribbean and northeastern Brazil. The process of turning sugar cane into granulated sugar, however, is very labor intensive. Due to the depopulating effects of Old World diseases, the number of Native Americans was not sufficient to meet the labor demands of the predominantly white-owned sugar plantations. This was also true for tobacco and cacao plantation. Thus, in order to supply labor for their plantations, Europeans imported million of Africans (some 9.3 in total) to work as slaves.
Europeans had their palettes sweetened by American sugar and chocolate, their nervous system stimulated by American tobacco, and their bodies clothed with American cotton, but at a tremendous cost to humanity. The death rate from the brutal treatment of slaves was high, and we can only imagine the magnitude of human suffering caused by a system that uprooted people from their homeland, often separated them from their loved ones, and forced them into hard labor for the rest of their lives.