Wall in Maltravieso Cave showing three hand stencils (center right, center top and top left). Photo: H Collado
Chris Standish, University of Southampton and Alistair Pike, University of Southampton
What makes us human? A lot of people would argue it is the ability of our species to engage in complex behaviour such as using language, creating art and being moral. But when and how did we first become “human” in this sense? While skeletal remains can reveal when our ancestors first became “anatomically modern,” it is much harder for scientists to decipher when the human lineage became “behaviorally modern.”
One of the key traits of behavioral modernity is the capacity to use, interpret and respond to symbols. We know that Homo sapiens have been doing this for at least 80,000 years. But its predecessor in parts of Eurasia, the Neanderthal, a human ancestor that became extinct around 40,000 years ago, has traditionally been regarded as uncultured and behaviorally inferior. Now our new study, published in Science, has challenged this view by showing that Neanderthals were able to create cave art.
However, evidence for such behavior by other human species is far more contentious. There are some tantalizing clues that Neanderthals in Europe also used body ornamentation around 40,000 to 45,000 years ago. But scientists have so far argued that this must have been inspired by the modern humans who had just arrived there – we know that humans and Neanderthals interacted and even interbred.
Cave art is seen as a more sophisticated example of symbolic behavior than body ornamentation, and has traditionally been thought of as a defining characteristic of Homo sapiens. In fact, most researchers believe that the cave art found in Europe and dating back over 40,000 years must have been painted by modern humans, even though Neanderthals were around at this time.
pigment in La Pasiega. J. Zilhão
Cave art, however, is often produced from mineral-based pigments which contain no organics, meaning radiocarbon dating isn’t possible. Even when when it is – such as when a charcoal-based pigment has been used – it suffers from issues of contamination which can lead to inaccurate dates. It is also a destructive technique, as the sample of pigment has to be taken from the art itself.
Uranium-thorium dating of carbonate minerals is often a better option. This well-established geochronological technique measures the natural decay of trace amounts of uranium to date the mineralization of recent geological formations such as stalagmites and stalactites – collectively known as “speleothems”. Tiny speleothem formations are often found on top of cave paintings, making it possible to use this technique to constrain the age of cave art without impacting on the art itself.
We used uranium-thorium dating to investigate cave art from three previously discovered sites in Spain. In La Pasiega, northern Spain, we showed that a red linear motif is older than 64,800 years. In Ardales, southern Spain, various red painted stalagmite formations date to different episodes of painting, including one between 45,300 and 48,700 years ago, and another before 65,500 years ago. In Maltravieso in western central Spain, we showed a red hand stencil is older than 66,700 years.
Our results are tremendously significant, both for our understanding of Neanderthals and for the emergence of behavioral complexity in the human lineage. Neanderthals undoubtedly had the capacity for symbolic behavior, much like contemporaneous modern human populations residing in Africa.
To understand how behavioral modernity arose, we now need to shift our focus back to periods when Homo sapiens and Neanderthals interacted and to the period of their last common ancestor. The most likely candidate for this ancestor is Homo heidelbergensis, which lived over half a million years ago.
Chris Standish, Postdoctoral Fellow of Archaeology, University of Southampton and Alistair Pike, Professor of Archaeological Sciences, University of Southampton
This article was originally published on The Conversation. Read the original article.
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