The question of how and when humans first arrived in South America represents a complex and ongoing scientific inquiry. Researchers combine insights from archaeology, genetics, and linguistics to piece together this ancient story. The journey involved overcoming significant environmental challenges, particularly vast ice sheets and changing sea levels, shaping the routes and timing of these early migrations.
The Initial Journey to the Americas
The prevailing theory for human entry into the Americas involves migration from Asia across the Bering Land Bridge, also known as Beringia. This landmass connected Siberia and Alaska during periods of lower sea levels, particularly during the Last Glacial Maximum (26,000 to 19,000 years ago). Recent research indicates the Bering Land Bridge emerged around 35,700 years ago, creating a window for human movement.
Early Paleolithic hunter-gatherers are thought to have crossed this land bridge. Genetic studies suggest ancestral Native American populations diverged from Asian populations around 36,000 years ago, coinciding with the land bridge’s emergence. While some evidence points to a small population residing in Beringia for thousands of years, their eventual expansion into the Americas occurred after 16,500 years ago, as glaciers began to recede.
Navigating the Ice Age Landscape
Movement from North America into South America presented challenges due to massive ice sheets covering much of North America. The Laurentide Ice Sheet covered eastern Canada, and the Cordilleran Ice Sheet extended along the western mountains. Two main hypotheses describe how early peoples bypassed these barriers.
One theory proposes an “ice-free corridor” that opened between the Laurentide and Cordilleran ice sheets. This inland route was once considered the primary path for the first Americans. However, recent studies indicate this corridor became viable for human travel only around 13,800 to 12,600 years ago. This timing suggests it was too late for the earliest human populations who were already present further south in the Americas.
An alternative and increasingly supported hypothesis is the coastal migration route. This theory suggests early peoples used watercraft to travel along the Pacific coast, bypassing the ice sheets. The “kelp highway” concept proposes that productive kelp forest ecosystems along the Pacific Rim provided abundant marine resources for these coastal migrants. This route, rich in shellfish, fish, and marine mammals, could have supported human movement from northeast Asia into the Americas as early as 16,000 years ago.
Unearthing Early South American Settlements
Archaeological discoveries in South America provide direct evidence of early human presence, supporting the coastal migration hypothesis. One significant site is Monte Verde in Chile, dated to approximately 14,500 years ago. This site yielded evidence of housing structures, wooden tools, plant remains including wild potatoes and seaweed, and bones from mastodons and other megafauna. The presence of seaweed, despite the site being inland, supports the idea of a coastal adaptation or connection. Older layers at Monte Verde suggest possible human presence as early as 18,500 years ago.
Another notable site is Pedra Furada in northeastern Brazil. Charcoal from ancient fires and stone artifacts at Pedra Furada have yielded dates ranging from 48,000 to 32,000 years ago, though these older dates remain controversial. However, more recent findings at Vale da Pedra Furada include a distinctive stone tool dated between 27,600 and 24,000 years ago, suggesting human occupation during the Last Glacial Maximum.
On the Peruvian coast, sites like Quebrada Jaguay and Quebrada Tacahuay provide evidence of early maritime adaptations. Quebrada Jaguay shows human occupation from about 13,000 to 8,000 years ago, with findings of fish bones, shellfish, and cutting tools. Quebrada Tacahuay, dated to approximately 12,850-12,130 years ago, also reveals evidence of an early maritime economy, including seabird and fish remains. These coastal sites suggest knowledge of exploiting marine resources, supporting the idea of a Pacific coastal route into South America.
Beyond Archaeology: Genetic and Linguistic Insights
Genetic studies offer a complementary perspective on the origins and migration patterns of South American populations. Analysis of mitochondrial DNA (mtDNA) and Y-chromosome DNA provides clues about ancient population movements. These studies indicate a shared ancestry with Asian populations and reveal complex migration patterns across the Americas.
Genetic data suggest the initial settlement of the American continent occurred around 14,000 years ago, aligning with archaeological findings. The distribution of specific Y-chromosome haplogroups and mtDNA lineages in South American indigenous populations indicates distinct male and female ancestries and suggests an early isolation of some groups. This genetic diversity supports a complex settlement process with multiple groups contributing to the peopling of South America.
Linguistic diversity in South America also provides insights into ancient population movements. The Americas exhibit a high number of distinct language families, with over 150 indigenous stocks in South America alone. Some theories propose that this extensive linguistic diversity points to a deeper time depth of human habitation than previously thought, as early as 35,000 years ago. Linguistic patterns, including “isolates” (languages with no demonstrable connection to others), suggest complex patterns of contact and migration.