Our uniform experience of intelligent causes allows us to make inferences about design, even without knowing the identity of the designers. If, as I and others have argued (for example, see here and here), ID principles are routinely used in various other sciences like geology and forensics, design inferences do — and should — fall within the proper domain of science, including biology. 

Archaeology is another example of intelligent design in action: the study of artifacts that have been designed for a purpose. By its very nature, archaeology begins when a design inference is made connecting observations to intelligent causes. A proper design inference, as Dembski and Ewert have presented in the updated edition of The Design Inference, is affirmed by noting small probability combined with short description length. For instance, consider a hard clay object on the ground. First, the archaeologist must distinguish it from a piece of dried clay formed naturally, such as results when a puddle of wet clay dries up. If the object bears markings, do they match an independently given pattern, such as the letters of an ancient alphabet? If the markings convey something meaningful, the probability would be very low that the markings formed naturally. The description length would also be short: “This is an inscription.”

Keeping the Design Inference Going

Once a design inference is made, though, design thinking does not stop. If the pottery shard says something, who said it, and why? The object itself might convey little information other than “somebody wrote here,” but by pattern matching with other clues, archaeologists can make further design inferences. From this we see that pattern matching extends the design inference in archaeology, in forensics, in SETI, and in most other cases of intelligent design. Upon receipt of a message from space, for example, SETI researchers would want to learn about the technological capabilities of the sender and the nature of their host star and planet.

New research tools are allowing archaeologists to ask questions about past civilizations — questions that were not tractable before. After a design inference has been established for an object, the focus has usually been on deciphering the message. But now, using new methods, scientists can infer the social context in which the message was written, shedding light on the cultural milieu and the intellectual environment of the messenger.

This goal brings other fields to bear on the investigation: history, linguistics, botany (e.g., dendrochronology), geology, stratigraphy, solar physics (e.g., correlating eclipses to written records), and psychology (when inferences to mental state are deduced from the structure of artifacts). Sometimes it overlaps with physics, too, as I will show. 

Many archaeological research programs, such as excavations of ancient cities, are well beyond the initial design inference and are now deep into follow-up questions. A key goal of archaeology is to place events into a reliable chronology because styles of artifacts often inform the intellectual history of a civilization (e.g., Bronze Age vs. Iron Age). Often, none of the data sources are precise enough individually, and so multiple sources are required for matching patterns between sources to place them on a timeline. Confidence is increased when multiple sources agree. For ambiguous cases, reasonable inferences can be drawn by interpolating between solid benchmarks of known date or provenance. 

Unsurprisingly, confidence decreases with age. Older sites have a corresponding paucity of artifacts that can be independently dated, requiring auxiliary assumptions in the attempt to arrive at dates that seem reasonable and consistent. Pattern matching, therefore, is both art and science — two skills requiring intelligent design. While the logic of design inference is straightforward, pattern matching requires judgment: giving proper weight to multiple sources.

Not-So-Hard Science

Physics, one of the hard sciences, seems best positioned to add confidence to timelines (but see this new worry about reproducibility). Within the dating methods physicists have devised, radiocarbon is best suited for archaeology. The decay rate (half-life of 5,730 years for ¹⁴C) is well established, but few may realize significant sources of uncertainty in the method, especially regarding production of ¹⁴C in the atmosphere. Radiocarbon experts know how to correct for anomalous measurements found at the onset of atomic bomb tests in the 1950s, but variations also occur due to solar activity over thousands of years. The 11-year solar cycle is well known but there are variations in the intensity and time of solar storms. Plus, the older the sample, the less ¹⁴C remains. 

For these reasons, the ¹⁴C clock is calibrated and recalibrated from time to time with a consensus calibration curve. The latest calibration curve is IntCal20. It relies on pattern matching with other sources of data, such as tree rings (dendrochronology). Recent advances in accelerator mass spectrometry (AMS) have refined the accuracy of tree ring dates. Even so, radiocarbon needs corroboration from additional data sources, particularly for “wiggles” and “plateaus” in the curve that reduce precision for periods of time that are decades or centuries in duration. In 2020, the year of IntCal20’s adoption, Cambridge University explained,

Radiocarbon (¹⁴C) ages cannot provide absolutely dated chronologies for archaeological or paleoenvironmental studies directly but must be converted to calendar age equivalents using a calibration curve compensating for fluctuations in atmospheric ¹⁴C concentration. Although calibration curves are constructed from independently dated archives, they invariably require revision as new data become available and our understanding of the Earth system improves. [Emphasis added.]

By this we see that radiocarbon dates in archaeology are not absolute. They can, however, improve with pattern matching — a form of design inference.

Case Study: Iron Age Jerusalem

One problematic “plateau” in the radiocarbon calibration curve is called the “Hallstatt Plateau” that renders dates between 770 and 420 BC unreliable. This is unfortunate, because many important historical events occurred in that timeframe. In the Proceedings of the National Academy of Sciences (PNAS), a team of 14 researchers, from archaeologists to experts in AMS and dendrochronology, demonstrated the art and science of pattern matching.

Establishing a detailed absolute chronology in an actively inhabited urban environment is challenging. The key to the solution is to apply stringent field methodologies using microarchaeological methods, leading to dense, radiocarbon-dated stratigraphic sequences. In Iron Age Jerusalem, 103 ¹⁴C measurements on samples from a range of contexts were used to reconstruct Jerusalem’s urban history. By wiggle matching against the calibration curve, a decadal resolution, not usually possible during the problematic 300-y-long Hallstatt plateau, was achieved. Results also revealed excursions in ¹⁴C concentration that were outside the ranges of the calibration curve, verified by a set of 100 calendar-dated tree rings. This field and lab approach could well be applicable to dating other urban contexts.

They referred to a method of interpolation within plateaus called wiggle matching. Wiggles in the radiocarbon calibration curve can be compared to small differences in calendar dates available from “microarchaeological” methods such as “in situ microstratigraphy” —

On the archaeological side, recent advances in sampling methods and context characterization using microarchaeological tools allow for more confident identification of in situ microstratigraphy and minimize chronological misfits (outliers) between ¹⁴C dates and archaeological contexts.

Let the Pattern Matching Begin

The more independent data, the better. The team members radiocarbon-dated seeds, pieces of linen, twigs, a bone from a bat, ash from burn layers, and other organic remains at widely distributed portions of the city and matched them against stratigraphy on a microscopic level. Finally, they integrated all their sources of information.

Absolute high-precision radiocarbon dating is pivotal in efforts to resolve complex historical and archaeological sequences. Jerusalem in the Iron Age (1200 to 586 BC) is a key site in its widespread archaeological importance but has not previously been a target for such an effort. The city has a history of 150 y of intensive archaeological excavations, stemming from the interest in ancient texts, particularly the biblical writings, which hold a thick and detailed historical record of king lists and significant political events. Surprisingly, though, radiocarbon dating was rarely applied for this period in Jerusalem, and the chronological frameworks were based solely on pottery typology, stratigraphy, and integration of textual sources. The complexity of the site’s formation processes, especially at the Southeastern Ridge (also known as the “City of David”), due to its sloping topography and the frequent rebuilding of the site from the Early Bronze Age up till the present, presents significant challenges to identifying in situ, well-characterized archaeological contexts for radiocarbon dating.

Data Overlap

The PNAS paper has all the trappings of ordinary science: maps, charts, photos, data, methods, results, discussion, and dozens of references. But it does intersect with “religious” sources (the biblical writings). This is not unusual. For chronology reconstructions, archaeologists commonly avail themselves of contemporaneous texts. The biblical writings, which they say, “hold a thick and detailed historical record of king lists and significant political events,” can be referenced like other historical records (Josephus, Thucydides, Egyptian or Babylonian inscriptions, etc.). Assessment of textual reliability is a job for scholars in other fields. 

The authors specifically refer to a mid-8th century earthquake mentioned by Amos (corroborated by geologists) and the destruction of Jerusalem by the Babylonians in 586 BC, described by Jeremiah, which the authors confirm is a “historically secured date” or “secure chronological anchor.” It has been confirmed by multiple texts (including Babylonian and biblical records and the historian Josephus) and by excavated destruction layers. Between these two secure anchors, they interpolated the dates of events described in texts with radiocarbon dates, building up a “chronological ladder” by matching the patterns from multiple data sources. This allowed them to add precision to other dating clues, such as pottery styles — a method that generally can only resolve events to within a century. Their work increases the precision by an order of magnitude.

This is the first step in improving the ceramic dating. As the data accumulate and the assemblages of narrow slices of time are published, the absolute ceramic data will be broadened and improved, particularly if large assemblages are exposed.

With greater precision, patterns of urban development came into sharper focus. One surprise was finding evidence that Jerusalem had experienced an earlier and larger population than previously thought, going back as far as the 16th century BC.

Altogether, almost 20% of the samples (18 dates) fall within the timeframe of the early Iron Age (12th to 10th centuries BC, Fig. 4). This is highly significant, since only in three cases (RTD10780, 9598, 9585) do the dates derive from contexts with clearly associated early Iron Age pottery, while the remaining dates come from charred remains from building materials. The abundance of early Iron Age dates, measured from all the areas in our study, clearly indicates widespread occupation of yet undetermined character, often underestimated due to the limited architectural contexts attributed to this period.

Additionally, they found evidence for significant urban expansion in the 9th century BC and after the mid-8th century earthquake. The radiocarbon dates inform some of the textual evidence:

Therefore, while the major building project of Jerusalem’s 8th-century BC fortifications was previously assignedto King Hezekiah in the late 8th century BC (e.g., ref. 59) based on our chronology, these activities can now be associated with the latter years of King Uzziah, whose reign spanned the mid-8th century BC, suggesting the city was fortified during the Syro-Ephraimite war (2nd Kings 15 to 16).

This implies that the texts informed the radiocarbon calibration curve, which in turn added clarity to the historical textual information — a form of feedback loop. When mismatches persisted, the scientists suspected physical causes:

The five dates retrieved from Sycamore 1, along its radius, demonstrate a rapid decrease in the measured radiocarbon amount, with the earliest determination, from the inner part of the beam, indicating an enriched radiocarbon content, measuring 2396 ± 31 uncal BP. These results suggest a higher influx of radiocarbon around 730 to 710 BC than predicted by the calibration curve. A similar effect was identified at around 2830 BC at the tell sites of Megiddo and Bet Yerah (SI Appendix, S4 and Fig. S48).

It is noteworthy that these results are consistent with some of the IntCal20 raw data for this time period (specifically those reported by Fahrni et al., 10), which also lie below the curve during the time interval in question. The fact that this offset and the one at 2830 BC occur below sharp minimum peaks of the calibration curve indicates that caution should be exercised when calibrating measurements that fall within such zones.

ID in Action

Pattern matching exemplifies intelligent design science in action. The design inference requires complexity that matches an independently describable pattern. In archaeology, increasing the precision of dates for historical events requires data input from multiple sources. This kind of pattern matching, incidentally, goes beyond the abilities of AI. Choosing which sources are most trustworthy requires judgment calls. But that’s true in almost all scientific research. It is why scientific findings are always tentative: subject to revision (one hopes, refinement). And that’s why it takes a mind — an ethical mind, with integrity — to follow the evidence where it leads.