1. The
Columbian Exchange

2. In Review?
Pangaea - was a supercontinent that existed about 300 million years ago.
About 180 million years ago Pangaea began to break up.
Through various land mass changes, Pangaea split along faults in the earth into two “super continents” and eventually some smaller land masses.
These two different continents developed into two completely different ecosystems.

3. ecosystem
An ecosystem is a community of plants, animals and smaller organisms that live, feed, reproduce and interact in the same area or environment.
Some ecosystems are very large.
On the other hand, some ecosystems may be physically small, such as you would find in a meadow at the edge of a forest.
While various forms of life may be found in both areas, the species that live in the forest ecosystem are usually very different from those that inhabit the meadow, even though the two environments are right next to each other.

4. The Movement of People
In turn we came to the conclusion that at some point in human history, people existed and began to spread out.
Over time human populations migrated in all directions throughout Africa, Europe and Asia
How and when did humans come to the Americas?
As original inhabitants of North America as far back as Pangaea.
Or people traveled over the Siberian Land Bridge known as Beringia

5. Humans evolved differently
Encephalitis, Small pox
Rabies
Flu, Pertussis
Measles, TB

6. Ecological collision
Now the stage is set for an ecological collision between these two completely different ecosystems.
As we reviewed, people from Africa, Asia and Europe had visited the Americas prior to Columbus.
However, with Columbus comes the great ecological watershed the world has ever seen.
Some people have compared this catastrophic event just as significant as the disappearance of the dinosaurs.
With the arrival of Columbus in the Americas, the animal, plant, and bacterial life of these two worlds began to mix.
By reuniting formerly biologically distinct land masses, the Columbian Exchange had dramatic and lasting effects on the world.

7. The Columbian exchange
Pangea as been resurrected and has reemerged.
No longer do two ecosystems exist.
The European ecosystem has invaded the North American Ecosystem.
This process, first studied comprehensively by American historian Alfred Crosby, was called the Columbian Exchange.
The Columbian Exchange is the movement of plants, animals, and diseases between the Eastern and Western hemispheres.

8. Ecological imperialism
Invasive species brought over by Columbus and eventually other European Explores took over the North American continent.
While the apparent and intentional transfer of domestic animals and home grown plants were obvious.
It was the unseen bugs, insects and bacteria which caused most harm.

9. Animals
The Columbian Exchange brought horses, cattle, sheep, goats, pigs to the Americas.
Within 100 years after Columbus, huge herds of wild cattle roamed many of the natural grasslands of the Americas. Wild cattle menaced the food crops of Native Americans.
Before Columbus, North American had no large animals and none of the other animals present in the Americas were suitable for domestication.
In contrast, Eurasia had 72 large animal species, of which 13 were suitable for domestication. So, while American had plenty of good food crops available before 1492, they had few domesticated animals.
Native Americans first encountered the horse as a fearsome war beast ridden by Spanish conquistadors. However, they soon learned to ride and raise horses themselves.

10. Before Columbus, the Americas had plenty of domesticated plants
Before Columbus, the Americas had plenty of domesticated plants. By the time Columbus had arrived, dozens of plants were in regular use, the most important of which were maize (corn), potatoes, cassava, and various beans and squashes. Lesser crops included sweet potato, papaya, pineapple, tomato, avocado, guava, peanuts, chili peppers, and cacao, the raw form of cocoa.
Within 20 years of Columbus’ last voyage, maize had established itself in Europe and North Africa.
Despite maize’s success, the potato had a stronger impact in improving the food supply and in promoting population growth in Europe and Asia.
. In turn the population explosion laid the foundation for other developments such as the Industrial Revolution and modern European imperialism. The potato has fed many populations around the world
Plants

11. By far the most dramatic and devastating impact of the Columbian Exchange was the introduction of new diseases into the Americas.
When the first inhabitants of the Americas arrived across the Bering land bridge, they brought few diseases with them.
Soon after 1492, Europeans inadvertently introduced these diseases to the Americas.
People who lived in Europe had developed immunities to these diseases because they had long existed among most populations.
However, the Native Americans had no such immunities, which produced catastrophic deaths throughout the Americas.
In all, between 1492 and 1650, perhaps 90 percent of the first Americans had died.
This loss is considered among the largest demographic disasters in human history.
Diseases

12. All this had nothing to do with superiority or inferiority of ecosystems in any sense. It has to do with environmental contrasts.
Native Americans were accustomed to living in one particular kind of environment, Europeans and Africans in another.
When the Europeans came to America, they brought with them all their plants, animals, and bacteria, creating a kind of environment to which they were already adapted, and so they increased in number.
Native Americans had not adapted to European bacteria, and so their population numbers plunged.
In turn the Europeans believed they were ordained by God to inherit the land.
The Impact