Earlier this year, a controversial paper concluded that human activity in the Americas is at least 130,000 years old. Although a lot of questions linger over the study, it served as a timely reminder that the idea that the first Americans were the 13,500-year-old Clovis people needed rethinking.

Now, writing in Science, an international team of anthropologists have essentially declared that the consensus has officially shifted. The team, led by San Diego State University, say that their review of the scientific literature has revealed that the first Americans turned up at least 18,000 years ago, almost certainly by boat.

The Clovis hypothesis posits that humans migrated from Russia’s northeastern tip through to Alaska via Beringia, a now-lost land bridge that protruded from the sea during the last glacial maximum. From there, they followed an ice-free corridor down the West Coast, and their descendants proliferated when the glaciers began to thaw.

This was based on archaeological evidence that still stands up today, but throughout the 20^th century, discovery after discovery seemed to poke holes through the idea that the first Americans were 13,500 years old. Recent work, along the coastlines of both North and South America, pointed towards there being hunter-gatherers on the continents long before the Clovis ever arrived.

Take Monte Verde, for example. The site in what is now southern Chile, first discovered in 1975, was found to contain primitive houses, hearths, and scraps of clothing. Human footprints were also found, including those of a child. This site is at least 14,500 years old, perhaps even 18,500 years old – predating the Clovis sites by at least a millennium.

Then you’ve got Page-Ladson, another archaeological site containing tools to butcher mastodons, extinct megafauna similar to elephants. The excavation of this Floridian site has been ongoing since 1959, and the most recent dating attempt puts it as being around 14,500 years old.

Evidence like this has been piling up for an age, and now academia agrees: the Clovis people were the second wave of immigrants to find the Americas. Earlier humans could have certainly used Beringia too to get into the US, but pre-Clovis times, the ice-free corridor was closed. That leaves only boats as a viable means of access.

The Coastal Migration Theory suggests that people could have made their way quite rapidly across the Pacific Ocean by following the islands dotted around the northern section of the Ring of Fire. The kelp that grew along this route ensured a burgeoning ecosystem of fishable food for those brave enough to make the journey.

This is likely how the true first Americans arrived – but who they are, or where they specifically came from, remains a total mystery.

[H/T: ArsTechnica]