Carbon dating is an accepted and peer reviewed scientific process used by the relevant academic disciplines since the 1950s as one of the primary methods to estimate the age of once living organic materials. When a living organism dies, it stops taking in new carbon. Simply put, the process measures the difference between the remaining amounts of decaying carbon compared to the amounts of stable carbon in the sample. The result produces an estimate of the time that has passed since the organism died.
The process does not reveal a precise date, but can give a fairly accurate date range, especially on objects older than a few hundred years. It can also measure the carbon produced from the above ground testing of atomic weapons, beginning at the end of WWII (rounded off to 1950). Results before 1650 (prior to the Industrial Revolution) and after 1950 (the Atomic Era) are reasonably accurate. The roughly 300 years in between does create some problems for precision as the introduction of massive amounts of artificial carbon from the burning of coal and other fossil fuels has skewed the results, often giving several date ranges. These results need further examination and research to determine likely age estimates.
In my personal experience, both times I had the same piece sampled by two different labs, the results were the same.
What about ironwood objects recovered from protected locations, such as dry caves and covered cliff ledges, or buried deep in the river mud (not subject to the constant grinding of gritty water)? Free from contact with the harsher environment and destruction from insects, it could be logically assumed these ironwood sculptures would survive for much longer periods of time. Not surprisingly, the carbon dating record supports this view. C14 results on these objects, are coming back with very early dates and in most cases, providing consistent dating ranges within specific ancient looking styles. For example, it is now common to get 900 to 1200 year old dates on one type of archaic looking cave guardian figure (see left image). As might be expected, on a slightly less archaic looking style with a more refined face, carbon dates are in the 600 to 900 range (see right image). Another group of recent discoveries, mostly objects found in western Borneo (often found buried in mud) are coming back with dates in the 2000 to 3500 year range.
Additionally, this skepticism about how old wood can survive ignores the reams of accepted data that less durable woods, several thousand years old, have been discovered in Egyptian, Chinese, and Central Asian tombs, not to mention perfectly preserved wood logs found in peat bogs that are 25,000 years old. And recent carbon dating, by archaeologists, on organic pigments sampled from cave paintings found in the same dry Borneo caves as the wood ossuaries, are showing results as early as 10,000 years ago! What is more durable, organic pigments or ironwood objects?
Someone once told me “what man can make, man can fake!” I agree that man made objects can be duplicated. For example art forgers can reformulate an old style of pigment and then paint on a cleaned old canvas to create a reasonable looking antique painting. They might be able to do a few tricks to simulate age by cracking the paint and applying layers of dust. Most of these fakes are eventually detected. But, is it easy to fake what nature does to wood over long periods of time? When it comes to ironwood sculptures, I still find it extremely unlikely that a forger can successfully duplicate a natural looking ancient erosion layer on a freshly re-cut surface. Despite the often-repeated claim by some dealers that this has happened, I have yet to see a proven example.
*Update: It was recently suggested that specific environmental conditions on Borneo Island may contribute to the early dates on their wood sculptures. The premise is the Borneo rain forest is so densely packed with trees that they expel higher amounts of oxygen and absorb higher levels of carbon. The additional carbon absorption is making the trees appear older when they die. Again, I asked Mike Sim of Rafters if this was possible. He response was that it had no effect on the carbon dating results, as the test measures the difference between the decaying c14 and the stable c13, which would be absorbed in the same ratio, regardless of higher levels of carbon in the region.
That all said, I am also not in favor of taking every single carbon 14 result on face value. As much as I accept the science and believe that many of these Dayak sculptures are in fact quite old (enough results are in to make this point), some potential anomalies need to be reconsidered. It is still possible the original results are valid, but when a specific piece doesn’t seem to fit logically in the time line, it should be set aside for additional research or at the very least note that there are still questions. As mentioned earlier, there will always be a few outliers, but that doesn't make the bulk of the data inaccurate.
I would have assumed most art collectors, dealers, and academics, a generally well educated and worldly group, are pro-science, but it seems there is a handful of skeptics within the tribal art community who believe that carbon dating wood is a magic trick meant to fool naive collectors or so horribly flawed the results are meaningless. Just as there are climate change deniers, this small, but increasingly vocal group of carbon dating deniers either do not understand or choose to misrepresent the process. Ridiculously, a few of the most vocal critics are dealers who praise carbon dates on their pieces and then hypocritically condemn similar dates on their competitor’s pieces. They can’t have it both ways. I encounter and confront these anti-science critics from time to time and frankly their negative arguments never hold up, as they are often based on obviously biased opinions and not factual evidence (that doesn’t keep them from continuing to use them). Nor is it always clear why they are obsessed with trying to discredit the process, as a few of these deniers seem to be on a nearly religious mission to condemn its use for dating tribal art.
It has been suggested that this new data must be discounted because it is upsetting previously accepted assumptions, therefore confusing the current scholarship of Dayak art. What's wrong with revising our viewpoint when new data becomes available? New discoveries have always changed the way we look at the world. The Sun does not revolve around the Earth, the Earth is not flat, the universe was not created in six days, humans have existed for longer than 6000 years, and some Dayak wood sculptures are older than a few hundred years. We shouldn't fear these discoveries, but embrace their possibilities.
Mark A. Johnson