Kent's Cavern, near Torquay, England, underwent systematic archaeological investigation beginning in the 1860's, proceeding intermittently up to the present day. There is a substantial Middle Pleistocene record of human occupation in the cave. The most important fossil human specimen is the Kent's Cavern 4 maxilla, preserving the right canine, third premolar and first molar and the bone holding them together, with a small piece of palate.
According to a story in This Is Devon, new AMS dating by the Oxford Radiocarbon Accelerator Unit has placed the maxilla between 37,000 and 40,000 years ago.
Barry Chandler, assistant curator at the museum, where the jaw bone is currently on display, said the new conclusions posed fresh questions. He said: "If the jaw is anatomically modern - from humans known as Cro-Magnons as Keith believed - then these people spread across Europe, reaching Britain far earlier than is currently thought.
"If, however, Keith was wrong and the jaw is from the human species known as the Neanderthals we will have the first direct evidence of Neanderthals on mainland Britain. We hope to resolve this problem by extracting ancient DNA from one of the teeth."
The Keith (1927) reference is below; I haven't seen it so I don't know what the argument is based upon. Looking at the maxilla, I just don't think there's enough there to make this diagnosis. It should be recalled that Keith's assessment was made during a time when the archaeological sequence was much less established, and there was an active effort to establish the existence of Homo sapiens alongside or previous to the Neandertals. My guess would be that this is a Neandertal; as Churchill and Smith (2000) describe it, there is no compelling association to a specific archaeological industry, so without a strong anatomical case there is no reason to think it is not Neandertal. I have not, however, seen the lateral side of the specimen. If anyone has a lateral or frontal view, I'd be really happy to see it. It could surprise me by being really informative, but even if it was clear whether a canine fossa or maxillary notch may have been present I'm not sure that would be sufficient to prove the specimen is modern.
At the same time, I'm not sure this is the best instance to try taxonomy-by-DNA. In fact, the most interesting possible result (a modern human DNA sequence) would be fundamentally equivocal. Would that mean this was a modern human? Or a Neandertal with a modern human sequence? Or contamination? There is really no way to tell, and that means that only the less interesting result (a sequence clustering with the Feldhofer specimens and other Neandertals) would be informative.
Further research on the jawbone fragment is planned with the aim of answering this question.
Chris Stringer, of London's Natural History Museum, and Erik Trinkaus, of Washington University in St Louis, US, will carry out a physical examination of the specimen to see if it carries any features diagnostic of either modern humans or Neanderthals (Homo neanderthalensis), their close cousins.
My only concern in this whole thing is the evident unwillingness of anybody to just look at the thing sitting on the museum shelf, until the current redating made it an issue. This is not a snipe against Stringer and Trinkaus at all -- first, because I can think of few better to settle this question, and second because they usually have better things to do than look at every bit of maxilla (albeit one of the only human remains associated with the early Upper Paleolithic in western Europe!). But how many clever British graduate students have there been who could have hopped a train to Torquay and done this observation 10 years ago? 25 years ago?
Let's hope this will make some graduate students consider where they might find the next Kent's Cavern 4.
The Palanth forum has spawned a nice thread on the Kent's Cavern dating, with references and additional information.
If you are interested in the history of the Kent's Cavern excavations, or even in visiting the place itself, there is a very nice virtual tour hosted by the proprietors.
Keith A. 1927. Report on a fragment of a human jaw found at a depth of (10 1/2 ft) 3.2 m in the cave earth of the vestibule of Kent's Cavern. Trans Proc Torquay Nat Hist Soc 5: 1-2.
Mellars P. 2005. The impossible coincidence. A single-species model for the origins of modern human behavior in Europe. Evol Anthropol 14:12-27.