I consider the days of old, the years long ago.
– Psalm 77:5 (ESV)
A new study out of Cornell University calls into question the standards associated with the carbon dating method used to date archaeological remains in the region of Israel. These findings lead to bigger questions about the radiocarbon dating process as a whole, which may have huge ramifications for how biblical events align with the timelines of the ancient world. The bottom line is that the history of Egypt and Israel may need to be rewritten.
Theories about the correct dates for events in the ancient world have been debated for centuries. Even modern archaeology experiences disagreements over what the timelines for different periods should look like. Since 1949, the process of carbon dating has become widely (if not universally) accepted to the point where it has supposedly settled many of those dating disputes.
Adding to the debate was the announcement of a recent study last month in the Cornell Chronicle. Sturt Manning, Professor of Classical Archaeology at Cornell University, and colleagues, recorded a series of carbon 14 dates in tree rings from southern Jordan near Petra that have sent tremors through the field of archaeology.
Manning chose to test juniper trees (Juniperus phoenicea) that were of a type used for building construction at Taybet Zaman, Jordan and could give unbroken sequences of rings back several hundred years. These tree rings were of known dates between AD 1610 and 1940. They showed that the average discrepancy between the known ages and those supplied by radiocarbon dating was 19 years. The carbon dates made the samples appear older than they really were.
Manning noted in the Chronicle that, “Scholars working on the early Iron Age and Biblical chronology in Jordan and Israel are doing sophisticated projects with radiocarbon age analysis, which argue for very precise findings. This then becomes the timeline of history. But our work indicates that it’s arguable their fundamental basis is faulty – they are using a calibration curve that is not accurate for this region.”
Carbon dating utilizes a very exact process present in nature to come up with its results. However, most are unaware that the Carbon dating results published for archaeological remains are not the raw results from the radiocarbon tests. The raw results have a “calibration curve” applied to them to reach the final number. This calibration curve adds additional assumptions to the process as well as additional opportunities for error.
Manning is the director of the Cornell Tree-Ring Laboratory, and is the lead author of “Fluctuating Radiocarbon Offsets Observed in the Southern Levant and Implications for Archaeological Chronology Debates,” published in the Proceedings of the National Academy of Sciences. He has published much other research on radiocarbon and tree-ring chronologies in the past.
“We have only investigated tree-rings from AD 1610-1940 so far, but we can reasonably assume that a similar pattern of radiocarbon fluctuations occurred in the centuries before for this region,” said Manning. “There has been much debate for several decades among scholars arguing for different chronologies sometimes only decades to a century apart – each with major historical implications. And yet these studies … may all be inaccurate since they are using the wrong radiocarbon information.”
This also raises the possibility that going further back in time might magnify the problem. When asked about the accuracy of radiocarbon testing, Manning told the Times of Israel, “If you only have radiocarbon but have a good set of data and a known archaeological sequence (e.g. stratified layers at an archaeological site) then you can hope to get within a few decades or so – so high-precision dating,” he says.
But then Manning added a significant disclaimer: “If you have nothing but a few radiocarbon dates, then you are more looking at ca. 50-100 years or so precision.”
This hints at a potential bias within the system. Why should the presence of stratified layers increase the accuracy of the radiocarbon results? Typically, tests produce a range of results and those results that fit best with the standard view are chosen, and the rest discarded as anomalies. This has the potential of perpetuating the standard view in a grand example of circular reasoning.
Of course, when lining up the archaeology found in Israel and Egypt with the biblical timeline, even a 50 to 100-year range can make the difference between nothing seemingly fitting the Bible, and finding a good fit.
Basics of Carbon Dating
The Carbon atom is the building block of all known physical life. According to Wikipedia, carbon dating (also referred to as radiocarbon dating or carbon-14 dating) is a method for determining the age of old organic material by measuring the amount of its radiocarbon, a radioactive isotope of carbon, also known as carbon 14.
Carbon 12 makes up about 99% of all naturally occurring carbon, while carbon 13 accounts for about 1%. These two forms of carbon are stable, meaning they don’t break down over time. A tiny fraction of the carbon in nature is carbon 14, which is unstable and mildly radioactive, meaning it emits particles over time, breaking down or decaying into something different – a stable form of Nitrogen.
Although carbon 14 is constantly decaying, it also constantly being produced. This happens in the upper atmosphere from cosmic rays striking nitrogen atoms and splitting them to produce C-14. Carbon 14 then combines with oxygen to form a particular kind of CO2 gas. Plants take this in during photosynthesis and it enters animals when they eat plants. In this way, the amount of carbon 14 in an organism reaches equilibrium with what is found in the atmosphere.
When an organism dies, it no longer exchanges carbon with its environment. From that point forward, the amount of carbon 14 in the remains of the organism steadily decreases because of its radioactivity. Since the rate of decay is known, the ratio of carbon 14 atoms to that of the stable carbon 12 and 13 atoms can be measured to indicate how much time has passed since the organism died.
For dates derived from the radiocarbon method to be accurate, a long list of assumptions and conditions must be met. One of the primary conditions is that the level of carbon 14 in the atmosphere must remain relatively constant. However, scholars know that this is not the case, which is why the calibration curve was developed in an attempt to correct for these fluctuations of C-14.
So teach us to number our days that we may get a heart of wisdom.
– Psalm 90:12 (ESV)
A Unique Problem in Israel
One cause for different levels of C-14 is that there is more of it produced in summer than in winter. Longer days and more direct sunlight means more cosmic rays (that are partially made up of rays of sunlight), which produce more C-14 in the atmosphere. One problem is that the entire northern hemisphere relies on a single standardized calibration curve constructed from measurements of radiocarbon levels in trees from central and northern Europe and North America.
The growing season for trees in more northerly latitudes is summer, but in much of Israel and Jordan the situation is the opposite. Summer is too dry and hot there, so the growing season for many varieties of plants is in the winter rainy season.
“We went looking to test the assumption behind the whole field of radiocarbon dating,” Manning said in the Cornell Chronicle. “We know from atmospheric measurements over the last 50 years that radiocarbon levels vary through the year, and we also know that plants typically grow at different times in different parts of the Northern Hemisphere. So we wondered whether the radiocarbon levels relevant to dating organic material might also vary for different areas and whether this might affect archaeological dating.”
“…trees growing in southern Jordan are showing a different amount of radiocarbon compared with trees in central and northern Europe, and in North America,” Manning stated.
Bigger Concerns for Carbon Dating
While seasonal fluctuations produce relatively minor differences in C-14 levels, more significant changes in the levels happen in the atmosphere over the course of centuries. The calibration curve actually adds about 2-3 centuries of time to the raw carbon 14 results by the time one gets back to the period of the biblical Exodus. Egyptologist, David Rohl notes that this means the raw results are actually close to his New Chronology. He proposes using carbon 14 to provide relative dates (which would show which finds are older than others), but not to derive absolute BC dates.
Rohl determined that problems in the way ancient Egypt’s historical timeline has been constructed by scholars show that it has been artificially over-inflated. His New Chronology proposal would shift the timeline of Egypt and Canaan forward by 2-3 centuries. The Bible’s timeline would be unaffected by this shift, since it comes from an independent source. This would make biblical events line up with archaeological history in a whole new way.
The Times of Israel article focuses on the threat Manning’s revised dates pose to the archaeology that supposedly supports Israel’s United Kingdom at the time of kings David and Solomon. There are finds in Israel that support a more organized central government emerging during part of the Iron Age, which many have tagged as evidence for the time of David and Solomon. Making those finds several decades younger would disconnect them from their supposed biblical connections. This has led scholars who support these links to downplay Manning’s findings.
In reality however, evidence throughout the Iron Age (where the standard view places Solomon) points to generally impoverished conditions in Israel that don’t fit the glorious empire of Solomon described in the Bible. This has generated skepticism among most scholars for the Bible’s account of Solomon – just as the apparent lack of evidence has caused skepticism for the biblical Exodus in the Late Bronze Age/New Kingdom.
Go back two or three centuries earlier from the standard placing of Solomon, however, and evidence reveals the height of what is called “Canaanite” culture. This time in the earlier Late Bronze Age is where the New Chronology places Israel’s United Monarchy. A previous Thinker Update highlighted a few of the things that remarkably fit the Bible’s Solomon account at this time.
One of the main objections raised against revising the timeline of Canaan and Egypt to this degree is radiocarbon dating. It is seen as generally supporting the standard timeline. However numerous authors, including David Rohl, have highlighted several major problems with carbon dating.
Radiocarbon results have produced chronologies that just do not line up with certain aspects of timelines constructed by different archaeological and historical methods. This has produced a dispute between archaeologists such as Manfred Bietak and scientists insisting on the reliability of radiocarbon methods. Normally, the differences between standard chronologies and carbon results amount to several decades, perhaps nearly a century.
But, could the problems be much greater?
Perhaps the most glaring issue is that for the present tree-ring sequence (on which the calibration curve is based) to reach back to the second millennium BC, several tree sections from Europe had to be linked together. To do this, a process called “wiggle matching” was employed to match similar patterns of wide and narrow growth rings from different trees, so they could be overlapped – extending the chronology back in time.
A simplified example would be the following: The first step is to combine a series of tree growth-ring sections from successively older material (such as timbers used to construct ancient buildings) to reach back 3,500 years. When the section of wood that is supposedly 3,500 years old (based on the number of rings in the complete sequence) is radiocarbon tested, the raw result is 3,250 years old. Since it is “known” that the sample is actually 3,500 years old, the calibration curve is constructed so that samples in future tests that yield raw results of 3,250 years old, are assigned a date of 3,500 years old, and this is the calibrated date that will be published.
The question is, are these wiggle-matched sequences valid?
As Rohl documents in his book Pharaohs and Kings, several of these tree-ring chronologies have had to be withdrawn after it was found that they contradicted each other. Additionally, some trees appeared to cross match with each other in multiple spots – resulting in computer produced wiggle matches that were supposedly as much as 99.9% certain at different points simultaneously. Sometimes these “unique” matches were centuries apart. Naturally, the ones closest to the expected results ended up being chosen as the correct place to join the two sequences.
There are other potential problems with the radiocarbon testing process such as old carbon eroding into the environment being tested. This may be the case with the Nile River eroding old sediment throughout the kingdom of the pharaohs year after year for millennia. This would produce artificially old results from everything tested in that environment.
If radiocarbon testing is not reliable, it opens the door for ideas that do not conform to the standard view, yet provide better fits between the Bible and archaeological evidence in periods considered by most to be too early. Keep Thinking!
TOP PHOTO: Sturt Manning coring a centuries old juniper tree near Petra in southern Jordan. (Credit: Sturt Manning, Cornell University)
