History

Gondwana

Towards the end of the dinosaurs, the southern super continent known as Gondwana, or Gondwanaland, broke into its modern-day fragments of South America and Africa from the west and Australasia, India, and Antarctica from the east. The complete fragmentation happened during the late Cretaceous, around 100 million years ago.

The Amazon-Congo

The Amazon River itself once ran in the opposite direction (east to west), and scientists think the Amazon joined to the Congo River in Africa when both South America and Africa occupied the same land mass. When the Andes formed by a collision of continental plates, they blocked the river causing a large saltwater, inland sea. Overtime, this inland sea became a freshwater lake with animals adapting to the different salinity.  Over 20 species of stingray in the Amazon River are more closely related to species in the Pacific Ocean than they are to other freshwater species.

The Isthmus of Panama

Around five million years ago, the South American continental plate converged with the North American plate causing formation of the Isthmus of Panama, which links North and South America. The isthmus caused flora and fauna that evolved independently in Laurasia (the northern super continent) and Gondwana to be mixed for the first time. The land bridge meant animals and plants from South America moved north, while those from North America moved south. For instance, the North American armadillo and porcupine have their roots in South America. And in the other direction, the South American llamas, bears, and cats, among others, moved from North America taking the journey south.

The First Humans

When our African ancestors left their origin they headed to Europe and Asia. The first journey took place around one million years ago. However, all living humans are descended from one small population that lived in Africa around 150,000 years ago. From Asia, some expanded south into Australia around 50,000 years ago. This left the Americas the last remaining habitable continents. From Asia, it is thought Homo sapiens crossed a land bridge joining Asia to North America across the Bering Straight. The land bridge was last exposed for a substantial period of time around 25, 000 to 10, 000 years ago. Stone tools similar to those found on the Siberian side of the land bridge were found on the Alaskan side from around 12, 000 years ago. A human site at the southern tip of Patagonia is dated to around 10, 500 years ago. These early human settlers in South America were the ancestors of the indigenous South American Indians.

The journey southward through the Americas is the greatest range expansion in human history. The journey was fraught with unimaginable dangers and encounters, such as the now-extinct megafauna e.g. giant sloths up to three tonnes in weight, one tonne armadillo-like creatures, beavers the size of bears, and saber-toothed cats.

European Colonisation

Columbus’s voyage in 1492 set the scene for the European colonization of the Americas. With the subsequent invading conquistadors came unfamiliar diseases never exposed to North and South American animals nor native people. Diseases Europeans had evolved some tolerance to over thousands of years would decimate Native Americans of both North and South America.

Contributing to the overwhelming victory of General Cortez over the Aztecs, smallpox had reached Mexico by 1520 carried by a slave from Cuba. By 1618, smallpox had reduced Mexico’s initial population from 20 million to 1.6 million, which left the survivors puzzled over the disease that wiped out their relatives and left the invading Spanish relatively untouched. This story was echoed over other areas of South America, such as Peru where in 1531 general Pizarro would go on to triumph over the Incan Empire of millions with only 168 men. The ease of victory supported propaganda on Pizarro’s side that victory was God’s will. However, smallpox had reached Peru in 1526 and along with measles, tuberculosis, and influenza had wiped out much of the population, including the emperor Huayna Capac. The fall of the emperor resulted in a civil war between his two sons over the throne—a war Pizarro exploited to his victory. It is estimated that introduced diseases wiped out 56 million Amerindian lives in the first years of the Spanish conquest.