An archaeological team, excavating at Chiquihuite Cave in northern Mexico, have found evidence of a human presence in that cave dating back to 30,000 years ago. They took 46 radio-carbon dates from sediment, animal bones, and charcoal on 1,930 stone artifacts and found that 239 of these artifacts dated to 33,000 years ago. And they claimed these artifacts were made by humans. This story spread across news sites like wildfire, and most of the news sites billed this as a true revolutionary Pre-Clovis find. The team published their research in the journal Nature, thus garnering more attention.
But these stories and the claims made by the team quickly came under much closer scrutiny quickly. When claims like this are presented, archaeological science takes over. At this point, the best archaeologists in the field begin to look very closely at the proofs presented. In this case, a whole group of expert archeologists like Vance Holliday at the University of Arizona, David Meltzer at Southern Methodist University, Loren Davis at Oregon State University and a host of others began to speak about their skepticism about this claim and why.
Here are the major critiques they made;
1) They do not see in the proofs presented in the research any convincing proof that these stone artifacts were actually made by humans. The presenters have to show the stones they see as made by humans are not natural but man made. One rock hitting another rock and breaking that rock into pieces can produce shards that look like man made tools. The artifacts in question have all been from very rocky places in the cave which supports a natural hypothesis.
2) The artifact styles do not change over 30,000 years which is suspicious when in all other areas of ancient human occupation styles evolve, and why are these artifacts that are supposedly 30,000 years old not seen anywhere in the area outside of this cave? Something this old would spread over time to at least nearby sites. All the supposed “tools” look the same. No evidence that there was use of local and non-local stone of varying quality is found at this site. And this area is rich in other kinds of stones that do not appear at this site. That dynamic is missing.
3) Humans living in one spot, a cave, for that long would leave behind evidence like hearths and butchered animals, and many other human proofs. How can it be that humans using the same cave for 30,000 years leave no trace of human DNA. The chances of that are astronomically small.
I write this article to point out the problems of positing a Pre-Clovis find based only on stone “tools” with no supporting evidence. As you can see from the critiques from the experts, this find is far from proven and looks very shaky. The news media should not sensationalize claims like this without consulting with others in the field first and moderating their coverage.
When the first posited proven Pre-Clovis find at Monte Verde was published, it took the team leader at the site, Tom Dillehay, 20 years to prove his case. Archaeological science is a tough, precise field where very definitive proofs have to be tested before they can be proven.