Those superior modern humans...

The spectre of cognition looms once again on the Neanderthal agenda. For years many authors have sought to maintain the position that our ancestors – the “modern” humans – were cognitively superior to their contemporaries, the “archaic” humans, including the Neanderthals. It was this superior intellect that was the cause of the rise of our species and the demise of all others. This has always been a difficult position to justify as there is no real evidence that this was the way in which the Neanderthals disappeared from our planet or indeed of how we colonised it. In the absence of evidence, hypothetical mutations that suddenly made us modern around 50 thousand years ago (kyr) have been postulated and the expansion of these modern humans into Europe has been inferred on the basis of stone tools that have been assumed, with little supporting evidence, to have been made by the new arrivals.

I have taken these arguments apart over the last few years, showing that the cognitive superiority and replacement argument is no more than a statement of faith which is unsupported by evidence. It is a kind of belief system that just does not go away. Even when we now know that our ancestors interchanged genes with the Neanderthals, to the degree that their genetic signal persists in us today, we insist in drawing distinctions. We seem obsessed in perpetuating the myth that we are the pinnacle of evolution; to maintain this position we must relegate all other humans, Neanderthals included, to a second plane.

In today’s blog I want to highlight the first of three recent papers that continue with the insistence that modern humans were cognitively superior to Neanderthals and that it was this that caused their extinction. I will deal with the other papers in subsequent posts. The three papers have one thing in common: they provide no direct evidence in favour of what they claim. Let’s start with the first one, a paper published last year in the Proceedings of the National Academy of Sciences USA (PNAS) [1]. The paper examined evidence of a volcanic eruption that occurred in southern Italy some 40 kyr. Evidence of the ash from the eruption in caves occupied by Neanderthals and modern humans was used to mark events before and after. The authors concluded that

“the combined effects of a major volcanic eruption and severe climatic cooling failed to have lasting impacts on Neanderthals or early modern humans in Europe.”

That may be so in so far as the limited geographical area that suffered the impact of the volcano goes; but absence of evidence is not proof of the alternative hypothesis. Despite this, the authors went on to say that

“We infer that modern humans proved a greater competitive threat to indigenous populations than natural disasters.”

In other words, they could not find evidence of the impact of the volcano on Neanderthals or modern humans and concluded that modern humans therefore had a greater impact on the Neanderthals; but no evidence of this modern human impact was provided. A case of “it must have been so”.

My take: the Neanderthals had gone extinct in the region by the time the volcano erupted, as shown by the authors. This means that the volcano could clearly not have had an impact on the Neanderthals as they were by then extinct! So we cannot test the impact of the volcanic eruption and subsequent climate on the Neanderthals. The modern humans, if that is what they were as we are relying largely on stone tools to identify them, may well have come into the region in large numbers to occupy the empty ecological space left by the volcanic eruption. There are just too many unknowns for us to tell what was going on...

[1] J. Lowe, et al. (2012). Volcanic ash layers illuminate the resilience of Neanderthals and early modern humans to natural hazards. PNAS 109: 13532-13537