Twenty-four stone chips, abandoned near the shore of a lake approximately 60-50 thousand years agoare moving the possible geography of Neanderthals a little further south. They come from Jebel Katefeh-1, in the Nefud desert, in northern Saudi Arabia. Their shape resembles tools associated with Neanderthals much more than those attributed to Homo sapiens. Enough to make us think that even our closest relatives have come this far. Enough, however, does not mean definitive proof: Neither Neanderthal fossils nor ancient DNA have been found in Arabia.
This is the most interesting part of the new study published on Quaternary Science Reviews by James Blinkhorn, Huw S. Groucutt and colleagues. Archaeologists didn’t simply look at a stone and decide who chipped it. They compared hundreds of artifacts and built statistical models trying to separate the effect of the environment, raw materials and type of site from that of the population that produced them. The result strengthens the hypothesis of a Neanderthal presence in northern Arabia, much further south than the Levant where their presence is directly documented.
Those splinters especially resemble those of Neanderthals
The research team has collected a database of 704 complete Levallois shrapnel coming from north-eastern Africa, Arabia and the Levant and dated between approximately 100 thousand and 50 thousand years ago. Levallois indicates a rather refined way of working the stone: first the core is carefully prepared, then a splinter is detached with a shape and size already largely foreseen. A sort of planning before the blow, very far from the image of the stone hit at random with a hammer.
Technique alone is not enough to recognize who was holding the stone. Homo sapiens and Neanderthals both knew Levallois systems. The researchers then analyzed the differences in the shape of the splinters and verified several possible explanations: age of the finds, environment, raw material used, composition of the archaeological assemblage, type of site and history of the populations. In the studio model, exactly population history better explains the observed variability.
When the system was tested on reference assemblies, those associated with Homo sapiens and those related to Neanderthals were distinguished with greater than agreement 93%. Then came the turn of the 24 shards of Jebel Katefeh-1.
For these, the median probability of classification in the Neanderthal group was 78%. Only four out of 24 artifacts were classified more likely in the associated with group Homo sapiens; almost a quarter exceeded the 95% probability of statistical association with Neanderthals. Seven finds from the nearby Al Marrat-3 site also show similar affinities, although with numbers too small to base any large conclusions on.
That 78%, however, must be kept in its place: . It is the result with which a statistical model classifies the shape of those artefacts with respect to the sets used to construct it. From here to declaring a human population found, something rather material is still missing.
The “desert” of 55 thousand years ago had a lake
Even the image of Neanderthals crossing the present-day Nefud under a merciless sun needs some adjustment. Jebel Katefeh-1 stands next to the remains of a ancient lake and the new datings place the occupation precisely during the transition towards wetter conditions.
The researchers used optically stimulated luminescence, a technique that allows them to estimate when sediment grains were last exposed to light. The new measures narrow a very broad previous history and place the site roughly between 60 thousand and 50 thousand years ago.
We have known for some time that the Nefud has often been very different from the desert we see today. A study published in Nature in 2021 he reconstructed at least five human population expansions in the interior of Arabia over the last 400,000 years, all coinciding with brief, wetter climate windows. One of these dates back to around 55 thousand years ago.
Even earlier, in 2012, research published in PLOS ONE had documented Middle Paleolithic sites along the shores of ancient Lake Jubbah. The reconstructed landscape was made up of prairies, a few trees and enough water to attract animals and groups of hunter-gatherers into the interior of the peninsula.
Jebel Katefeh-1 also did not appear on the archaeologists’ map yesterday. A previous study dedicated to the site had already described its rich set of Levallois tools and highlighted the similarities with Middle African and Levantine Paleolithic traditions. The new research tries to take a further step: understand who may have produced them.
The desert therefore remains important in history, but it must be looked at with the eyes of 55 thousand years ago. Lakes, vegetation and animals could open corridors for limited periods through territories that became much more difficult to cross during the drier phases.
There is still no evidence that could close the matter
If the attribution is confirmed, Jebel Katefeh-1 would considerably expand the territory frequented by Neanderthals towards the south and would show a greater ability to move in open and warm environments compared to the old caricature of the European hominin nailed to the cold and caves. The authors also suggest that Arabia may have been one of the territories where different human populations met during the Pleistocene.
However, there is a rather concrete methodological limit. The database used for comparison lacks open-air Neanderthal sites perfectly comparable to Jebel Katefeh-1. The type of site can influence which tools are produced and abandoned, and although the authors attempted to statistically separate the effect from that of the population, caution remains necessary.
The most solid confirmation would be of a much less abstract form: a bone, a tooth or ancient DNA from the same archaeological context. Materials that are difficult to preserve for tens of thousands of years at low latitudes, which is also why stones are doing much of the work in Arabia.
For now we can say that someone was working stone on the shores of a lake in northern Arabia about 55 thousand years ago and that the way they did it surprisingly resembles that observed in Neanderthal sites. The name of whoever held those splinters in his hands has become much more plausible. Written in stone, however, it is not yet there.
