Is the proposed 2.1 MY old hominin occupation at Shangchen, China, an eolithic location?

Zhu et al report a find of 2.1 MY old stone artefacts in the Lantian area of central China. This would make it the earliest well attested evidence of hominin presence outside Africa and therefore has important implications. Unfortunately, they report finding only stone tools. Is this yet another Eolith location? That is, is it a location that contains stone material that is most likely naturally modified only and is not the result of human activity? Having been a fairly consistent critic of early occupation claims that are based solely on lithics, I was interested to see this new report.

I will leave the evaluation of the dating itself to others. But if we accept the dating and the association of the proposed artefacts with the dated layers, we still have quite a bit of evaluation to do. There are three main criteria for the evaluation of a potential eolithic location. Any time someone claims hominin occupation based on stone tools alone, all three criteria must be evaluated.

1. The assemblage in context

How different is the proposed assemblage from the group of rocks from which it was selected? In most cases, not very much. Here the authors give us some very clear and very helpful data. “At Shangchen, 88 flakes and 20 unmodified stones were found in situ between S5 and L28”. That is unusually precise for such a claim, and also encouraging. Most of the rocks found were idenfitied as artefacts. In some eolithic sites, a few tools are identified among thousands of mostly uniformly broken rocks. The very fact that there are so few rocks at the location overall, both identified as artefacts and not, is encouraging.

2. Distance to the raw material sources

Is the site near the possible sources of the lithic raw materials? Often sites that turn out to be likely eolithic locations are right on top of raw material sources, and the stone tools are identified right out of the raw material beds themselves. In this case, “no natural stone exposures (for example stream beds or outcrops) were encountered” at the site itself, and potential sources are reported as being 5 to 10 km away. This, also, is encouraging.

3. Shock factor and plausibility

How plausible, or conversely, how shocking is the claim? The conventionally accepted date for a solid earliest find in Eurasia (although very much to the west of this) is Dmanisi, around 1.8 MYA (Hawks, among others, challenges this). But for the sake of argument, let’s accept it for now. Dmanisi is a securely dated assemblage that includes actual hominin fossil material. Hard to beat in terms of direct evidence of hominin dispersal. It is definitely not an eolithic location.

At 2.1 MY, the Shangchen find is 16% older than Dmanisi, so let’s give it a “shock factor” (SF, to sound more scientific) of 1.16 (Claimed local age / Accepted regional age, or CLA/ARA, just for fun). By comparison, accepting an oldest occupation of the Americas at around 15kya, a claim like the probably eolithic Pedra Furada in South America (Boëda et al  2014) has an SF of 1.6, the Cerutti Mastodon site (Holen et al 2017) has an SF of 8.7, and the decidedly eolithic Calico Hills site from California has an SF of up to 133. So as far as early occupation claims go, Shangchen is therefore not overly shocking.

Any claim with an SF under 1.0 is inherently plausible, which of course, doesn’t make it true, and it should still be examined. But, especially given the vagaries of archaeological dating and chronology, a claim that comes in at an SF of 1.16 shouldn’t exactly blow our minds. Still, it is above 1.0 and so needs a very careful assessment before we use it to update to the textbooks.

Shock factor itself doesn’t directly help determine the eolithic status of a claim. The other two criteria do most of the heavy lifting for that. However, SF does help us assign a probability or likelihood to our conclusion. A site that clearly meets the other two criteria for eolithness but has an SF < 1 may or may not be eolithic. Who knows? A site that meets the other two criteria and has very high SF is more likely to be eolithic.

Assessment

Overall, judging by the published material only, the Shangchen claim seems solid. It meets none of the usual criteria for an obvious eolith location, and is likely to be the result of hominin activity. Combine that with a fairly low SF, and it’s likelihood of being a real archaeological find goes up.

It doesn’t feature the most impressive curated assemblage ever, but it is in a type of material I know well, and it is far from the worst I have seen. If it is indeed 2.1 MY old, it pushes back some boundaries, but not by all that much. I will be interested to see how this new evidence affects hominin dispersal scenarios.

References

Boëda E, I Clemente-Conte, M Fontugne, C Lahaye, M Pino, G Daltrini Felice, N Guidon, S Hoeltz, A Lourdeau, M Pagli, AM Pessis, S Viana, A Da Costa, E Douville 2014a. A new late Pleistocene archaeological sequence in South America: The Vale da Pedra Furada (Piaui, Brazil), Antiquity 88:927-955.

Holen et al 2017. A 130,000-year-old archaeological site in southern California, USA, Nature 544:479-483.