What is the leading theory about how early humans arrived on the American continents?
• They walked from Africa to South America when those two continents were part of the same landmass.
• They walked from Asia to North America over a strip of land that has since been covered by the ocean.
• They sailed in large ships from Australia to North America.
• They canoed from Antarctica to South America when the climate there became too harsh.
The leading theory about how early humans arrived on the American continents is that they walked from Asia to North America over a strip of land that has since been covered by the ocean. This hypothesis is known as the Bering Land Bridge Theory or the "Beringia" hypothesis.
To explain how to get to this answer, we can look at the available options and evaluate the evidence and scientific consensus.
The first option suggests that early humans walked from Africa to South America when those two continents were part of the same landmass. However, the geological evidence does not support the existence of a land bridge connecting Africa and South America during the time when early humans migrated. Additionally, there is no genetic or archaeological evidence to suggest such a route.
The second option, which suggests that early humans walked from Asia to North America over a strip of land, is supported by substantial evidence. During the last Ice Age (around 30,000 to 11,000 years ago), sea levels dropped, exposing a vast land bridge called Beringia between present-day Siberia and Alaska. This land bridge connected the continents, allowing for migrations to the Americas.
Archaeological evidence such as artifacts, ancient tools, and remnants of human campfires have been found along the coasts of Siberia and Alaska, reinforcing the idea that early humans migrated across this land bridge.
Genetic studies have also provided evidence of a common ancestry among Native American populations and East Asians, supporting the theory of a migration from Asia to the Americas.
The third option, suggesting that early humans sailed in large ships from Australia to North America, lacks substantial evidence. There is no archaeological or genetic evidence to support this hypothesis. Moreover, the vast distances and challenging oceanic conditions between Australia and North America make long-distance boat travel highly unlikely during the time when early humans were migrating.
The fourth option, suggesting that early humans canoed from Antarctica to South America, is not supported by scientific evidence. The extreme climate conditions in Antarctica, along with the vast distances and lack of archaeological or genetic evidence, make this hypothesis highly unlikely.
Based on the available evidence and scientific consensus, the most plausible theory is that early humans migrated from Asia to North America over a land bridge called Beringia.