For some time, experts have thought people first arrived in the Americas from the so-called “Old World” around 15,000 years ago. Early explorers would have come across the Bering Land Bridge from modern day Russia to Alaska and down, and also spreading up from South America. Or so we thought. Researchers now believe that they’ve found evidence of humans in the Americas that dates back over 130,000 years.The study, published in the academic journal Nature, details and analyzes the remains of an ancient mastodon. Authors posit that the mastodon was buried in a way consistent with human activity. That sounds spurious, but I can assure you, as someone with a degree in biological anthropology I can confirm that it’s often pretty obvious if remains were buried intentionally. You won’t typically find bones arranged in patterns without intervention, for example.What’s more is that the mastodon’s remains show evidence of damage from human tools. All of this has been known for some time, and it was accepted to be one of the oldest sites in the Americas already. Recent uranium-thorium dating, however, revealed that these remains might be far older than we first thought.AdChoices广告Study co-author, Steve Holen, noted that the site was in spectacular condition with no geological disturbance. “So we can eliminate all of the natural processes that break bones like this.”Other experts in the field caution that the bones might not be quite as old as they appear. Each method radiometric dating has different pros and cons. Some work with certain types of material or only with substances that between specific ages. Uranium-thorium dating, used here, isn’t often applied to bones, leaving some skeptical. Still, radiocarbon dating has failed, indicating that the remains are likely at least 60,000 years old.“The results are completely astounding, as it’s very unexpected that there would be any evidence of humans in North America that are this old,” Beth Shapiro told The Verge. Shapiro, a professor in paleogenomics at UC Santa Cruz said she believed the data had been “reasonably interpreted.”While I never got to the Ph.D. level myself, I can say that the findings seem valid but odd. And they certainly leave a lot of questions. Human activity is generally pretty easy to track across the planet. Every time we go somewhere new, we tend to cause massive extinctions of large animals as we hunted them and destroyed their natural environment. Plus, because humans are so recent, many of our tools and bones are pretty close to the surface and easy to find. If we really did arrive in the Americas more than 100,000 years ago, we’d have expected to have found more fossils around the same age. They may well be out there, but it’s not like people haven’t been looking. The west coast is densely populated with lots of activity and yet… very little.It may be a while yet before we know for sure what these findings mean, but they are remarkable nonetheless, and they may raise some big questions about our history. That’s science for you — always more questions than answers.