One thing that is mentioned in passing in the Jesus Tomb documentary is the DNA testing. It immediately struck me as odd that they will release fairly detailed supporting documents for all other “evidence”, but that the DNA analysis is not really shown in detail anywhere.
I previously commented on the types of DNA needed for testing. One can do either mytochondrial DNA testting, or nuclear DNA testing. mtDNA establishes a maternal relationship only, while nuclear DNA is inhereted from both parents.
There is a lot of precedence for the testing of ancient DNA, most notably on mummies. DNA testing on mummies has shown this type of testing to be quite hard. DNA is one of the first things that decompose. Decomposition will break up the DNA strands, which will lead to false sequencing. The factors that lead to decomposition include temperature, PH and the availibility of oxygen and water.
Higher temperatures will degrade DNA quicker. Temperatures approaching 30C will lead to quick degradation, and anything above 35C will destroy DNA over the long term. At a constant 35C, chloroplast DNA will only last ~800 years (Marota, 2002), and that is the most optimistic calculation.
The higher PH of bone may lead to slightly longer DNA preservation times, but it will not counteract the total temperature effect.
Dehydration will extend the timeline for extracting useful DNA significantly, as will the total encapsulation of the remains. Ancient burial rites used neither, the body was simply wrapped in linen and placed in a tomb. Humidity in tombes range from 30-70%, depending on location and outside conditions. In Jerusalem, the average mean humidity is 65%.
The other (greater) threat is that of contamination. If just one single modern cell contaminates the sample, then the test is essentially worthless.
Now, let’s look at the samples from the Jesus Tomb. Taking into account the above limitations of DNA testing, I am not surprised that the makers place more emphasis on the historical and statistical evidence.
The ossuaries were recovered from a tomb which would have closely assumed the temperatures and humidity of the outside environment. In Jerusalem, the temperatures fluctuate between 10 and 30C annually, more than enough to affect the samples over the 2000 year period. In addition, the relatively high humidity (65% annual mean) is also enough to have a significant environmental effect. Leaking rain and groundwater may also lead to standing water on the floor of the tomb, leading to higher levels of humidity.
Any time the tomb was opened and closed, the temperature and humidity would have fluctuated more severely.
The bones would not have been dehydrated by any artificial means such as cremation, it would just have been a normal decomposition process. We read that Jesus was wrapped in aloe and myrrh (John 19:39). From what I could determine, both of these are slightly acidic, which would enhance DNA preservation. However, normally, after about a year, remains were removed from the linens, and put in a limestone box, just as was the case in the Jesus Tomb. Any kind of water interaction with the limestone would lead to an alkylization process, leading to strand cleavage and reducing the probability of DNA preservation.
According to the documentary there was no bones, they used “human residue”. Using just standard analysis, as if the DNA testing was done right after the ossuaries were found, it seems that reliable DNA testing will be pretty tough to assert. Anyone handling the bones could have left blood or hair inside the box, contaminating the original contents.
But wait, there is more…
These ossuaries were found in 1980,, and stored under uncontrolled conditions. One of them was even left in an open courtyard. Some of them are scrubbed on the inside. The temperature and humidity in the warehouse where these boxes were stored for the last 27 years is likely to be slighly hotter and more humid than the outside, unless it is airconditioned. Many people scratched around in these boxes, to remove bones and to look for artifacts, so the possibility for modern contamination is high. Remember, all it takes is a single cell to contaminate.
At this point, I am prepared to state that unless they found teeth in the boxes, and extracted the mtDNA from the inside of those teeth, we can pretty much disregard any DNA evidence.
Update – Rich Deem adds this:
According to the film’s website, DNA testing was attempted on only two samples – those of “Jesus” and those of Mariamene. The DNA was so degraded that no sequencing could be determined from the nuclear DNA (the main chromosomes). Only mitochondrial DNA (mtDNA) was available for sequencing. Since mtDNA is much smaller than nuclear DNA, the average person’s mtDNA differs from another’s by only 8 base pairs. In closely-related communities, differences would be much less. The film’s website did not give any details about the testing other than the claim that the individuals “were not related.” The Lakehead University Paleo-DNA Laboratory (where the DNA testing was done) has been contacted for additional information. Since “Jesus” and Mariamene were unrelated, the filmmakers assumed they were married and had a son named Judah (from the ossuary “Judah, son of Jeshua”). The assumption that Mariamene is really Mary Magdalene is quite overstated, since the the name of “Mariamne” from the Acts of Philip is not the same as Mariamene. In addition, the Acts of Philip is the work of a heretical community that lived in the fourth century – at least two hundred fifty years after the events of the New Testament. (Bones of Jesus)