New study: Humans reached America 100,000 years earlier than we thought

New research published online this week in the journal Nature is claiming that the first humans found their way to the Americas far earlier than previously believed –  more than 100,000 years earlier, to be precise – but not everyone seems to be on board with the study’s findings.

In the study, scientists from the Center for American Paleolithic Research in South Dakota and their colleagues examined animal bones and tools unearthed from the Cerutti Mastodon site near San Diego, California – a site initially discovered in 1992, according to BBC News reports.

Among their discoveries were potential stone tools and remains believed to be from a mastodon, the British news outlet added. However, the researchers were unable to use radiocarbon dating to analyze the remains, so instead they used a technique known as uranium-thorium dating.

Those tests, the study authors said, claimed that the artifacts were 130,000 years old – significant because most prior research has concluded that the Clovis people were the first people to come to the Americas across the Beringia land bridge some 13,000 years ago, Scientific American noted.

If the CAPR-led team is right, the publication added, “the find could call into question the long-held assumption that H. sapiens was the first and only member of the human family to reach the New World, because it hails from a time when multiple human species… roamed the planet.”

Study’s conclusions largely dismissed by other researchers

Furthermore, Scientific American said, it would indicate that archaeologists had somehow missed more than 100,000 years worth of human history in the New World. However, many members of the scientific community are skeptical of the researcher’s findings, to say the least.

In their study, lead author Steven R. Holen and his colleagues reported that rocks found near the purported mastodon remains appear to show signs of wear and tear suggesting that they were had been used as anvils and hammerstones, BBC News said. Furthermore, the bones and teeth bore a “characteristic breakage pattern” suggesting that the creatures were attacked with hard objects.

A researcher holds a mastodon molar fragment found under a rock anvil discovered at the California site.(Image credit: SDNHM)

A researcher holds a mastodon molar fragment found under a rock anvil discovered at the California site.(Image credit: SDNHM)

“We have conducted two experiments breaking elephant bones with large rock hammers and anvils,” Dr. Holen told the UK media outlet. “We produced exactly the same kind of fracture patterns as we found on the Cerutti mastodon limb bones,” he said, adding that they were able to “eliminate all of the natural processes that break bones like this. These bones were not broken by carnivore chewing, or by other animals trampling on this bone.”

So the bones clearly must have been broken by human activity, then, right? Southern Methodist University anthropologist Dr. David Meltzer is unconvinced. “You can’t push human antiquity in the New World back 100,000 years based on evidence as inherently ambiguous as broken bones and nondescript stones – not when they are coming from a highway salvage excavation done 25 years ago, and you have none of the detailed taphonomic evidence demanded of such a grandiose claim,” he told Scientific American.

“It is one thing to show that broken bones and modified rocks could have been produced by people, which Holen and his colleagues have done,” University of Washington archaeologist Donald Grayson added. “It is quite another to show that people, and people alone, could have produced those modifications. This, Holen [and his colleagues] have most certainly not done, making this a very easy claim to dismiss.”


Image credit: A. Rountrey, C. Abraczinskas and D. Fisher/Univ. Michigan