Humans began crossing Beringia, the land bridge connecting Eurasia to Alaska more than 15,000 years ago. The reasons and motivations for their long journey are still unclear, but once arrived in Alaska they spread across both Americas, taking on a southward path.
The echoes of ancient conflicts between science and religion are still haunting the search for the first Amerindians. Native American Indians and scientists were arguing for decades over the identity of the first inhabitants of the Americas.
The scientific evidence pointing to the fact that the Amerindians are not quite so indigenous as they would like to believe and in fact they might be descendants from the same stock as their European conquerors was, at first, not received well by the Amerindians tribes. Since then many years have passes but the question of the first Americans continued to spark many controversies.
Recently, the issue of Native Americans' origin has come again under debate, after a team of researchers have published the findings of their study. The research team was pointing on a newer date for the arrival of Amerindians' ancestors and in only one migratory wave, unlike what histories previously thought.
Genetics can play an important role in giving a final answer to this question. Since things tend to move very fast in the scientific community of the 21th century, another new DNA study published in Nature, links now some Amazon tribes to Indigenous Australians. This new genetic analysis comes again in controversy with the previous study that supported the theory of only one founding group, from a single migratory wave.
According to reports, new evidence suggests that Brazil's Surui people share ancestry with indigenous Australians. The previous study published not long ago supported the theory that the first Americans descended from this one group of founders and arrived in a single wave. But the other genetic analysis suggests that some Amerindian tribes in the Amazon region share a common ancestor with indigenous New Guineans and Australians. This supports the rival theory stating that not one but two groups have arrived in Americas in two different migratory waves, to give rise to the first Americans.
David Reich, the co-author of the study and geneticist at Harvard University, explains that another early population that founded modern Native American populations has been found by using genetic analysis. In the year 2014, genetic analysis linked DNA from a 12,000-year-old skeleton from Mexico to modern Native Americans. Since then, genetic studies have connected ancient and modern humans to ancestors arrived from Eurasia.
Previously, Reich's group had found genetic evidence supporting the theory of a single founding migration. But when his team started to study genomes from cultures in Central and South America, a researcher from the team, Pontus Skoglund, noticed that the Karitiana and Suruí tribes of the Amazon have more genetic ties to indigenous groups in Australasia such as Andaman Islanders, New Guineans and Australians, than to Eurasians.
From a need to look at Amazonian populations deeper, the Harvard lab teamed up with Brazilian researchers in order to collect more samples from Amazonian tribes. They studied together the genomes of 30 Native American groups native to Central and South America and compered them to each other, as well to those 197 populations from around the world.
According to the report, the Amazonian groups Xaante, Karitiana and Surui have more in common with Australasians than any group in Eurasia. It is even possible that this ancestral population dubbed "Population Y" may even have crossed to Americas before the "First Americans", which means the First Americans may actually be the Second Americans.
