The photo above was shot in a cave in the Indonesian Island of Sulawesi (Indonesia is a large group of islands north of Australia).
Pay close attention to the stalactites above the chap’s head, and also to the ‘hand’ outlines on the wall (you will see another one on Daily Dose of Banksy #34). I’m sure that your school Art has told you about those hand outlines (if it has told you about Banksy then it *must* have told you about this ancient art).
Here is a photo from another cave:-
You can see the hand outlines again. However, this cave is in El Castillo, Northern Spain and, until these recent discoveries, was thought to be the oldest art ever.
So, what are these “hand outlines” & how on earth do they know how old the paintings are?
Lots of art dating from prehistoric times has been discovered in caves in Spain & southern France, and one of the recurring motifs is the outline of a hand. There is only one way that this could possibly have been made:- someone took some paint in their mouth (probably ‘ochre’, an iron oxide pigment), chewed it up a bit, placed their hand on the wall as a stencil & then sprayed the paint all over the back of their hand (and the wall).
It makes a classic piece of graffiti. The strangeness is that is has been found in France, Spain, Argentina, Borneo & now Indonesia and was made exactly the same way. Most odd.
The first key is that the caves are in Limestone rock.
Limestone is Calcium (minority Magnesium) Carbonate, and that gets (just a little) dissolved by rainwater. Carbon dioxide gas dissolves a little bit in the rainwater, and that makes normally-neutral water a little acidic. The limestone is a little bit alkaline, which means that the solid rock will dissolve in the water - just a little (and, of course, that is how the caves were formed in the first place). However, the process can also go in the opposite direction, and especially if limestone-rich water has a chance to stay still for a little while, and perhaps evaporate a little; and that is how stalactites get formed.
The second key is that stalactites begin to form over the top of the artwork (more accurately, a crust of calcite).
The third, and crucial, key is much more technical...
Although the encrustations that have built up over the top of the artwork are mostly calcium carbonate (‘calcite’, also called ‘chalk’), as remarked above they can also be formed from magnesium carbonate, or have that variant of chalk as part of the mix. It is also possible for other atoms than chalk/magnesium to be present in the crust (though in even smaller proportions than magnesium). One of these is Uranium (a natural presence, and nothing whatsoever to do with the modern use in energy or bombs). Uranium is radioactive and naturally decays into thorium at a very precise rate through the ages. The process is well understood & is used to date rocks & bones (the latter contains lots of calcium carbonate).
Uranium-thorium dating has been around for decades, but the technique has now been so refined that only a tiny sample is required to get a good result.
The U-T dating technique was used by a team led by Dr Alistair Pike from Bristol University, UK, on the El Castilo paintings, using thin films immediately above the hand stencils. The date is (at least) 37,300 years (coinciding with the first known immigration into Europe of modern humans (Homo sapiens). Before about 41,000 years ago, it is their evolutionary cousins, the Neanderthals (Homo neanderthalensis), who dominate the continent). That was published in June 2012, and at the time made that art the oldest known such cave art in the world. The Sulawesi hand art has beaten that record!
Dr Maxime Aubert, of Griffith University in Queensland, Australia has used the same U-T dating method & established that one of the hand stencils is (at least) an astonishing 39,900 years old, the new “oldest hand stencil in the world”.
No other form of life uses Art as humans do, and it well worth asking ‘Why?’. The fact of art, and it’s development in human kind across the ages, indicates the development of “Abstract Thought” & “Symbolism”, and that is where the hand stencils stand out.
Somehow, that stencil represents human kind, and it’s desire to make a mark. Thus also the beginnings of artistic (and human) endeavour, and the development of language. The Ethnologist wants to know, “just how old is this endeavour, and when & how did it start?”
--------- Alex Kemp