So you’ve heard about that 130,000-year-old Mastodon butchery site in San Diego?
The one that has clear evidence of an unknown hominid in the New World 100,000 years earlier than even the earliest estimates of occupation?
And how the site has been thoroughly studied and vetted by archaeological experts and found to be valid?
Well then, I have pitch for Herbal Life that you’re going to love.
While it’s not fair to characterize anyone who takes the claims of early hominids in the New World as naïve, it does demonstrate a prevalent problem of Science Communication. This is an arena in which sensational claims garner front-page attention without necessarily going through a detailed scientific process. An arena in which extremely technical experts are the only people who can refute extremely technical claims, and their refutations rarely make the same waves as the initial “scientific findings”. An arena in which click bait travels faster than the actual science needed to refute it. This arena is “Internet Pop Science” and while the Cerutti Mastodon Site has all the trappings of real science (and certainly some real paleontology worked in there), it is the perfect example of the Internet Pop Science phenomenon and the damage it can do to the public understanding of Science.
For those of you not familiar with the Mastodon article that blew up the science news outlets last week, I’ll give you a quick recap:
In the early 1990s, during a freeway construction project in southern San Diego County, a paleontologist from the Natural History Museum named Richard Cerutti found some Mastodon bones. Upon closer inspection, he noticed some odd things in regards to this particular mastodon skeleton. One of the tusks was standing upright, as if it had been buried vertically into the ground. Certain parts, like the ball joints of the femoral heads had been separated and seemingly placed together. And many of the bones appeared to be broken open when the bones were fresh, as if by scavengers trying to get at the Mastodon marrow. In addition to the skeleton itself, Cerutti found some stone cobbles with impact marks reminiscent of being used like a hammer and anvil to bash open the bones.
Cerutti dug the site and brought in experts from around the country to help him analyze it. After advances in radiometric dating techniques, he was able to get a 130,000-year-old date on the bones. Steven Holen, a Ph.D. archaeologist with The Center for American Paleolithic Research came in to look at the potential stone tools and certified them as definitely being reminiscent of ancient hammer and anvil technology.
In putting all this together, Cerutti surmised that the only possible conclusion was that some hominid smashed open these mastodon bones 130,000 years ago with the cobble tools at the site. This, of course, would completely upend human paleontology and archaeology as our own species, H sapian was completely contained to Africa at the time. And no other hominid species had even been found in the New World. So in essence, this one paleontology/archaeology site completely changed the history of hominids, New World occupation, and paleontology of San Diego. Pretty impressive stuff, which is probably why it was published in the Gold Standard of scientific publication, the journal Nature.
It’s a great story and one that is likely viewed with awe and wonder from anyone outside the fields of archaeology and paleontology. It seems to be one of those ‘Huge Discoveries’ that change the way we think about the planet and its history.
And it is, most likely, complete bullshit.
Cerutti’s site has been a poorly kept secret in archaeological/paleontological fields in San Diego for the last few decades. Something that gets whispered about by young field researchers chasing the thrill of science that they thought would accompany sharing a career title with Indiana Jones. I was exactly such a young archaeologist in 2009 when working with Richard Cerutti on a different site, he told me of his treasured Mastodon find. This was before the dating had come in and at the time, he thought the site was even older, giving me a proposed date prior to half a million years old. I was immediately hooked. Evidence of hominid occupation in the New World prior to Homo sapiens?! And right in my own backyard?! I felt the rush of being in on a secret that would change the world and I gobbled every piece of information I could about the site from Richard himself until eventually, he broke down and brought me his preliminary report to read. After tearing through the document, I was crestfallen.
“Richard…” I started unable to contain my disappointment, “Where are the lithics?” You see, in sites of animal butchery, hominids utilize sharp-flaked stone tools (or lithics) to cut away soft tissue before busting open the bones for marrow. These flaked lithics are telltale signs of human activity and the marks that they leave on the bones are as telltale as the lithics themselves. Neither the lithics nor their cut marks were present at this site meaning to me, and every halfway skeptical archaeologist out there, all Cerutti had was some bashed up bones and possibly associated cobbles. While it didn’t rule out this Mastodon site as being altered by hominids, it certainly wasn’t the only possibility, or even the most likely one. Cerutti had no good answer for this.
Maybe they were quarrying bone shards for tools? But all of the bone shards large enough to make tools appear to still be present at the site according to Cerutti’s own refits.
Maybe they scavenged an existing carcass that was long devoid of meat? But then how fresh would the bone have been when broken? (Cerutti’s team’s own “Experimental Archaeology” tests on current elephant bones were on rather fresh bone that would still have tissue on it in a natural setting and this was their evidence that the bones had to be broken when still fresh.)
Also, among the damaged bones was at least one tooth that was also smashed open. There is no marrow within teeth and no reason to smash them open but a random event, like a trampling by other Mastodons or hydraulic activity from the river adjacent to the site would indiscriminately smash teeth along with bones. And these “stone tools”, while certainly suggestive of intentional bashing are nebulous without other evidence of hominid activity. The site’s location alongside a river could have contributed to the cobbles smashing into each other and the bones, causing the damage noted.
The lead archaeologist brought in to assist Cerutti, Steven Holen, addressed many of these issues as they were inevitably raised by other archaeologists in the past week or so. He admits they don’t have the expected flaked lithics (or their cut marks on bone) but he contends, we have other Mastodon kill sites in North America without those lithics. In fact, in the rebuttals to the site’s critics he mentions two sites, a 14,000-year-old site and 33,000-year-old site of mastodon butchery (or bone quarrying) without such artifacts that prove that flaked lithics aren’t necessary for accepted archaeological sites like this. When I first read that reply, I had to go over it a few times to make sure I read it right. I am unaware of any accepted Mastodon-related archaeology site, with or without lithics, at 33,000 years ago in the New World. In fact, I’m unaware of any accepted archaeology site in the New World anywhere near 33,000 years ago. I did some quick research and found that the site referenced is a proposed archaeological site in Nebraska that is not accepted by mainstream archaeology. Despite a lack of lithics at the site and other possible issues regarding definitive proof that the Nebraska site has any archaeological elements, it is promoted by its main advocate and lead researcher: Dr. Steven Holen.
Essentially Dr. Holen is claiming, “You know that crucial piece of evidence we don’t have at this site that you’d expect to be here? Well, we have other examples of accepted sites without those as well so they’re not that important. Granted, I’m the one who ‘accepted’ that other site too, but…”
Further looking into Dr Holen’s group, The Center for American Paleolithic Research, you’ll find a rag tag group assembled for the purpose of finding evidence of ancient hominid occupation of the New World. And that is exactly the problem. Cerutti didn’t bring in mainstream Pre-Clovis researchers to analyze his find; he brought in a fringe scientist who has already made some dubious claims and is basing his work here upon those claims. He brought in someone with a stated agenda to confirm the type of site Cerutti was proposing. There are experts who just deal with actual ancient New World archaeological sites like Tom Dillehay, who could have come in and given Cerutti an objective analysis of his find and its relation to other, accepted ancient American sites. Instead he brought in someone who was biased towards accepting such sites and got the sensational story that accompanies that type of person.
Looking at the evidence that the team has presented, I see the same problems now as I did when I first read Cerutti’s paper in 2009. There simply is no definitive evidence of hominid altering of the skeleton 130,000 years ago. In science, extraordinary claims require extraordinary evidence and in the case of this site extremely extraordinary claims are being made with decidedly thin evidence. Even if we take The Cerutti team’s assertion that the bones were broken when fresh and that the cobbles are indeed tools, there are non-extraordinary explanations. Like a Mastodon getting trampled 130,000 years ago and then natives creating and using tools at the same general location (possibly even to bust up the same bones) 100,000 years later. Or hydraulic activity (remember, we’re alongside a river) causing both the battered cobbles and broken bones. Heck, as long as we’re spitballing ideas, the possibility of other Mastodons revisiting and manipulating the site of their relatives’ bones (as we know modern elephants do) and smashing them with rocks themselves is more plausible than postulating a previously unknown North American hominid based on the given evidence. And that’s not even considering more complicated possibilities like the original bones being buried in sediment intact and because of anaerobic conditions, fracturing as if fresh when they were later visited by natives sometime in the last twenty thousand years.
So by now you may be wondering, “How in the world did this article, with all its inherent issues, make it through peer review in the most prestigious science journal on the planet?” The answer is simple: It didn’t. Nature didn’t publish any peer-reviewed article regarding the Cerutti Mastodon site. It simply published a letter from the investigators describing their finds. This letter is more of an announcement of something interesting researchers have found and is in no way a vetted, peer-reviewed, scientifically reliable description of the find.
There’s nothing wrong or underhanded about this. It’s a common practice that keeps the scientific community informed about relevant discoveries while proper academic papers are being crafted. But it does give the impression to the public that this is somehow settled or accepted science. It’s not. It hasn’t even reached the threshold of consideration that is peer review. Maybe Cerutti will turn out to be right. Maybe hominids occupied San Diego 130,000 years ago, and if that turns out to be true I’ll be very excited to jump on that bandwagon but right now, there's no sober, evidential basis for that claim. Right now, it’s just a letter making some extraordinary claims without regard to their responsibility for extraordinary evidence.