The questionable science of paleoanthropology

For whatever reason, I've never had much interest in which group of humans or proto-humans went where in pre-history.   But it sure sounds like the people who work in the field can make some very big claims based on very dubious evidence:

When researchers made the astonishing suggestion last year that early humans settled the Americas 100,000 years earlier than thought, they asked doubters to keep an open mind and consider the evidence backing their claim. But their study¹, which proposed that mastodon bones from California were broken by an as-yet-unidentified group of early humans 130,000 years ago, was instantly questioned by archaeologists. Most researchers agree that humans settled the Americas around 15,000 years ago.

Nearly a year later, the sceptics are still not convinced. In a rebuttal to the work, published on 7 February in Nature², archaeologists say that modern construction equipment better explains the mastodon bone damage than does the handiwork of ancient hominins. They present an analysis of mammoth bones from Texas that, they say, have similar-looking damage, which was caused by natural wear and tear and heavy equipment.

In the original study, a team co-led by Tom Deméré, a palaeontologist at the San Diego Natural History Museum in California, examined bone fragments of a mastodon (Mammut americanum), an extinct relative of elephants, that had been found during roadworks in suburban San Diego in the 1990s. Deméré and archaeologist Steven Holen at the Center for American Paleolithic Research in Hot Springs, South Dakota, contended that the remains bore telltale fractures seen in bones struck by the stone tools of early humans. No obvious stone tools or human remains were found at the site.
Deméré’s team also established that the mastodon bones were around 130,000 years old, and suggested that an unknown hominin species had reached California by that time. Current scientific consensus on settlement of the Americas is that early humans from Asia crossed the Bering land bridge into Alaska around 20,000 years ago, a theory based on archaeological research and studies of modern and ancient DNA.

To rebut the mastodon claim, Ferraro’s team examined a site in Waco containing the remains of at least 26 mammoths that died about 60,000 years ago. Archaeologists have previously looked for evidence of humans at the site and found none. According to Ferraro, some of the mammoth bones were battered and broken in the same way as the bones from the San Diego site.

Ferraro thinks that construction work — some of the Waco mammoth bones were found during a building project — and natural wear can explain the similarities.