Thursday, May 18, 2017

Alternative Archaeology: Gobekli Tepe and the Sphinx

On a recent JRE podcast, skeptic Michael Shermer went head-to-head with Graham Hancock and Randall Carlson, two proponents of alternative archaeological theories. The debate could be summarized as follows: Hancock and Carlson argued that the simplest explanation for the presence of ancient archaeological sites, like Gobekli tepe (below image) and the Sphinx, is that there was a transfer of knowledge from an unknown advanced civilization to the builders of those structures. Shermer argued against their thesis by citing the fact that most archaeologists dispute their claims, and that there is little to no positive evidence in favor of their hypotheses. According to Shermer, the default position should be to side with the majority of experts. 

The “mainstream” view among archaeologists is that the Gobekli Tepe site, found in southeast Turkey, was built by hunter gatherers around 9000 BC. Hancock and Carlson argue that the mainstream account is wrong because of the presence of several, otherwise inexplicable, anomalies. In response, Shermer accuses Hancock and Carlson of focusing on negative evidence rather than producing positive evidence for their view. Finding some problems with a well-established theory is easy to do. Finding good evidence for alternative theories is evidently very hard. How should a layperson adjudicate the debate between “mainstream” and “alternative” archaeologists? In this post, I will argue that Hancock and Carlson’s arguments for the existence of an unknown ancient civilization are not persuasive. In the process, I will critically assess some of the specific anomalies cited by Hancock and Carlson.

Before addressing their reasoning, it is useful to know the backgrounds of both Hancock and Carlson. Graham Hancock is an author and journalist who has written extensively about the mysteries of ancient civilizations. Randall Carlson describes himself on his website as a “master builder and architectural designer, teacher, geometrician, geomythologist, geological explorer and renegade scholar.” Neither are experts in archaeology, a discipline that seems most relevant to assessing their claims. However, their lack of credentials does not affect the quality of their arguments. They either have good reasons for accepting their views or they don’t.

Hancock argues that the presence of Gobekli Tepe cries out for an alternative explanation. Before 9000 BC, there is no archaeological record of the gradual development of skills and technology you would may expect to find. For example, archaeologists have not found less sophisticated stone structures found dated around twelve or thirteen thousand years ago. Gobekli Tepe is the oldest stone structure we have found and it appears as if its construction came out of nowhere. Without any evidence of older structures or ancient civilizations, what is the best explanation for its presence? Hancock argues that the best explanation is that an advanced civilization taught hunter gatherers how to build the stone structures. 

There are several problems with Hancock’s reasoning. First, he expects there to be archaeological evidence for the gradual development of skills, but apparently does not expect to find the same kinds of evidence for his proposed advanced civilization. Hancock’s only evidence for an advanced civilization is indirect: the mere existence of Gobekli Tepe. A second problem with Hancock’s argument is that he makes an assumption that he provides little warrant for: that hunter gatherers could not have learned how to build the structures on their own in a relatively short period of time (i.e. hundreds or thousands of years). Let’s compare Hancock’s hypothesis with some others.

Burst hypothesis: The skills required to build Gobekli Tepe were acquired and honed in a relatively short period of time (hundreds of years), solely by the hunter gatherers.

Gradualist hypothesis: There was a gradual development of skills but the evidence was not preserved well or it is all still underground.

As it stands, most would agree that there is probably much more evidence to uncover. But in order to favor Hancock’s Transfer of Knowledge (ToK) hypothesis, one would need to show that both the burst and gradualist hypotheses were less likely to be true. I take the ToK hypothesis to be the most extravagant because it posits the existence of a civilization we have no evidence for. The other hypotheses just make, in my view, reasonable assumptions about humans we know existed. How does Hancock try to establish that ToK is the best explanation? 

It seems like Hancock, Carlson, and Rogan are all incredulous about the burst hypothesis. But given that they all lack expertise in cognitive science and anthropology, they are not in a position to say what the limits of human cognition or social learning were at the time. Thus, they are committing the fallacious argument from personal incredulity. Hancock gives a second reason to reject the burst hypothesis. He points out that the mainstream archaeological community had long thought that hunter gatherers were not capable of building something like Gobekli Tepe. Experts no longer believe that in light of recent archaeological finds, such as Gobekli Tepe, that were undoubtedly built by hunter gatherers using stone age technology. Skeptical of the recent change of expert opinion, Hancock appeals to what the experts used to think to justify his belief that hunter gatherers couldn’t have pulled it off. 

Hancock is not in a position to rule out the gradualist hypothesis either. In order for his own hypothesis to be taken seriously, he needs to assume that there is a lot of hidden or destroyed archaeological evidence. But one would make the same assumption in order to support the gradualist hypothesis. Without any independent reason for favoring ToK over the gradualist hypothesis, it would seem that the simpler explanation would be the latter.

But of course, Hancock and Carlson do think there are independent reasons for positing the existence of a lost ancient civilization. They go even further when they suggest that this same lost ancient civilization was responsible for teaching many of the early civilizations (e.g. Egyptians) how to construct megaliths. Their evidence consists mostly of anomalies found in other archaeological sites that do not fit well with the standard accounts. One of the main pieces of evidence they refer to is the apparent water erosion on the enclosure walls of the Great Sphinx. The Great Sphinx is widely thought to have been built around 2500 BC. But in order for the weathering markings on the enclosure walls to form, you would need much more rain than was present at the time of its construction (1). So, if there was not enough rain around 2500 BC, then it must have been built much earlier than we previously thought (~6000 BC). That, or the idea that there is evidence of water erosion is simply mistaken.

The vast majority of archaeologists, geologists, and Egyptologists reject the water erosion hypothesis for two main reasons. First, the weathering marks can also be accounted for by other factors such as wind erosion, quarrying activities, or rainfall runoff (Reader 2001; 2006, Lacovara 2004, Vandercruys 2006). Second, there is no archaeological evidence of an advanced civilization around that area that predates the Egyptians. [It is often pointed out that absence of evidence is not evidence of absence, but that is only true when the evidence should not be expected. In the case of an advanced civilization, you would expect there to be some kind of evidence, not only for the civilization at its peak, but for the gradual development of the civilization. In this case, we have reasonable grounds for thinking that absence of evidence is in fact evidence of absence.]

The simplest explanation is that there was no water erosion from intense rainfall to begin with. Hancock and Carlson do not seem to take this possibility seriously, suggesting that either they know something the archaeological community does not (e.g. the weathering marks could only be caused by intense rainfall at an earlier time), or that they have missed something the archaeological community is aware of. The same possibility remains for the remainder of their "evidence". In interpreting the empirical record, expertise is sometimes required. Those who are lacking certain kinds of knowledge about, say, the methodology of geologists or archaeologists can easily go astray. Given that Hancock and Carlson do not have formal backgrounds in the relevant fields, it is possible that they have unwittingly misinterpreted the evidence. 

There is usually a good reason why alternative theories are given little weight. It's not that most scientists are closed-minded, it's that they are very skeptical. Alternative theories tend to be lacking in the evidence department, and so when they get criticized, the proponents often feel like they're getting an unfair shot. But given the nature of scientific inquiry, and the extravagance of many of the alternative theories, one should not expect anything different. If there was an advanced civilization that aided the hunter gatherers at Gobekli Tepe, it will take some high quality evidence to convince the scientific community. Hancock and Carlson should continue their research, but it's reasonable to conclude that they're probably wrong. 

(1)  Geologist Colin Reader (2001, 2006) has proposed that the Sphinx was built several hundred years before the mainstream timeline, a time in which there would have been enough rain to directly cause the weathering marks. 

Works cited

Peter Lacovara. (2004). The Pyramids, the sphinx: tombs and temples of Giza. Bunker Hill Publishing, Inc.

Reader, C. D. (2001). A Geomorphological Study of the Giza Necropolis, with Implications for the Development of the Site. Archaeometry, 43(1), 149-165.

Reader, C. (2006). Further considerations on development at Giza before the 4th Dynasty. PalArch’s Journal of Archaeology of Egypt/Egyptology, 3(2), 12-25.

Vandecruys, G. (2006). The Sphinx: dramatising data… and dating. PalArch’s Journal of Archaeology of Egypt, 1, 1-13. 

No comments:

Post a Comment