Less than 20,000 years ago, humans took the first steps on one of the most important journeys in history by traversing the Bering Strait across an icy bridge from Siberia to Alaska. Over the coming centuries, they slowly but surely migrated down across the Americas, eventually settling in South America some 10,000 years later. But who were these people? What did they look like? And how exactly did they make these epic migrations?

Scientists have been bickering about these questions for decades and, despite huge advances in the fields of genetics and archaeology, much of the story remains as hazy as ever. However, two huge new studies, made up of 72 researchers from eight countries, are hoping to fill in some of the gaps.

As reported in the journal Science and Cell, anthropologists have sequenced genomes of 15 ancient humans from across the Americas, spanning from Alaska right down to Patagonia. 

Their findings confirm the existence of a single ancestral population for all American ethnic groups (aka Amerindians) both past and present. It appears that these people were closely related to populations living in Siberia and northern China at the time. Furthermore, it indicates that the descendants of the first American settlers diversified into different lineages through three big waves of migration, starting 16,000 years ago. The first wave arrived in South America around 15,000 and 11,000 years ago, followed by a second wave around 9,000 years ago, and a less significant third wave around 4,200 years ago.

The oldest human remains in the Americas belong to a woman known as “Luzia” – sometimes called the “first Brazilian” – who lived in the Lagoa Santa caves of Brazil some 12,000 years ago. Luzia and the Lagoa Santa people were among the first wave of people in South America and, it turns out, were actually partial descendants of Clovis migrants from North America, not Africa or Australia as was once believed. 

"From the genetic standpoint, the Lagoa Santa people are descendants of the first Amerindians,” André Menezes Strauss, from the University of São Paulo's Museum of Archeology and Ethnology, said in a statement.

“Luzia’s people must have resulted from a migratory wave originating in Beringia,” added Tábita Hünemeier, a geneticist at the University of São Paulo, referring to the now-submerged Bering land bridge that joined Siberia to Alaska.

Unfortunately, the remains of Luzia were heavily damaged in the colossal fire that destroyed Brazil’s National Museum in September, though not all of her was lost.

Scientists have previously attempted to reconstruct the face of Luzia based on her skull shape. However, now that researchers have a good idea of her genetics, they have a much clearer idea of how she might have looked – and they were way off, it seems. 

 "The genetic results of the new study show categorically that there was no significant connection between the Lagoa Santa people and groups from Africa or Australia,” added Strauss.

"Accustomed as we are to the traditional facial reconstruction of Luzia with strongly African features, this new facial reconstruction reflects the physiognomy of the first inhabitants of Brazil far more accurately, displaying the generalized and indistinct features from which the great Amerindian diversity was established over thousands of years.”