Here is the resultant analysis and conclusion:
The Science Behind Hair, DNA, and Forensic Mysteries: Understanding the Impact of Hair Samples on Forensic Conclusions:
Imagine you're watching a true crime documentary. The
investigators have found a crucial piece of evidence—a single strand of hair.
They send it to the lab, hoping it will provide the answers they need to crack
the case. But what exactly can a hair sample reveal? And how reliable is the
information it provides, especially when it comes to complex forensic cases
like the Somerton Man mystery?
To fully understand the power of hair in forensic science,
we need to explore the differences between two types of hair samples: one that
includes the root, and one that is just a rootless shaft. These differences
have profound implications for what investigators can learn from these samples,
and ultimately, how reliable their conclusions might be.
Hair Samples: Rooted vs. Rootless
When it comes to analyzing hair, the presence or absence of
the root is crucial. A hair sample with its root intact contains nuclear DNA—the
complete set of genetic material found in almost every cell of the body. This
type of DNA is highly specific to an individual, providing a detailed genetic
profile that can be used for identification, genealogical research, and even
health assessments.
On the other hand, a rootless hair shaft only contains mitochondrial
DNA (mtDNA). This type of DNA is found in the mitochondria, the
energy-producing structures in cells, and it’s passed down exclusively from the
mother. While mtDNA can provide useful information, it’s far less specific than
nuclear DNA. Because mtDNA is shared among all maternal relatives, it can’t
uniquely identify a person the way nuclear DNA can.
To illustrate the differences between these two types of
DNA, let’s look at a simple chart that compares them:
Here's a comparison chart:
What This Means for Forensic Conclusions
These differences between nuclear and mitochondrial DNA are
more than just scientific trivia—they have real-world implications for forensic
investigations. Let’s break down how they can impact the outcome of a case.
- Accuracy
and Specificity:
- Nuclear
DNA (from a hair root) is incredibly accurate and specific. It acts
like a genetic fingerprint, providing a match that is unique to the
individual. This makes it a powerful tool in criminal investigations,
where pinpointing the exact person involved is crucial.
- Mitochondrial
DNA (from a rootless shaft), while useful, is less definitive. It can
include or exclude someone from a maternal lineage, but it can’t provide
a unique identification. This means that in cases where only mtDNA is
available, the conclusions drawn must be more cautious.
- Likelihood
of Misinterpretation:
- The
high specificity of nuclear DNA minimizes the risk of misinterpretation.
If a match is found, investigators can be confident in their conclusions.
- With
mtDNA, there’s a higher chance of ambiguity. For instance, if mtDNA links
a suspect to a crime scene, it might also link their maternal relatives,
potentially leading to confusion or false leads.
- Admissibility
in Court:
- Nuclear
DNA evidence is gold standard in courtrooms. Its reliability makes it a
cornerstone of many legal cases.
- Mitochondrial
DNA, while admissible, carries less weight. Judges and juries are often
advised to consider its limitations, particularly the fact that it cannot
uniquely identify an individual.
- Impact
on Cold Cases:
- In
cold cases, where evidence might be decades old, nuclear DNA can provide
definitive answers and close cases that have remained unsolved for years.
- Mitochondrial
DNA, though useful, might only help narrow down suspects to a maternal
lineage, rather than providing the conclusive proof needed to solve the
case.
The Role of DNA Imputation
DNA imputation is a technique that scientists use to fill in
missing pieces of genetic data. It’s like using a puzzle’s reference image to
guess where missing pieces should go. In large-scale genetic research,
imputation is invaluable. It allows scientists to predict missing genotypes in
a sample based on patterns found in a reference population.
However, when it comes to forensic science, particularly
with hair samples, the role of imputation is limited. Since imputation relies
on nuclear DNA, it can’t be applied to rootless hair shafts, which only contain
mitochondrial DNA. Therefore, in cases where only a rootless hair shaft is
available, like in the analysis of the Somerton Man’s hair, imputation doesn’t
improve the results.
While imputation is incredibly reliable in the right
context, such as large-scale studies where it can increase the power of genetic
research, it isn’t typically used in forensic cases where the utmost accuracy
and specificity are required. Forensic scientists prefer directly observed DNA
sequences, especially in legal contexts where the stakes are high.
The Case of the Somerton Man
To bring this all together, consider the Somerton Man case.
This mysterious unsolved case from 1948 has intrigued investigators and
researchers for decades. In 2022 claims were made that Carl Webb was the
Somerton Man, based on DNA extracted from a rootless hair shaft and
supplemented by imputation techniques. However, given the limitations of mtDNA
and the role of imputation, these conclusions must be viewed with caution.
The absence of nuclear DNA in the hair shaft means that the
evidence is not as definitive as it might seem. While it’s possible to trace a
maternal lineage using mtDNA, the unique identification of an individual, like
Carl Webb, requires nuclear DNA. Without it, the claim remains speculative,
highlighting the importance of understanding the science behind forensic
evidence.
Complicating Factors: Embedding and Embalming
The situation becomes even more complex when considering
additional factors like the condition of the hair sample over time. In this
case, supposedly the rootless hair sample had been embedded in a sisal/plaster
casing for 70-plus years and the body from which it came had been subjected to
embalming. These factors would further complicate the use of DNA imputation:
- Prolonged
Embedding in Sisal/Plaster Casing:
- The hair sample's exposure to environmental factors such as temperature, humidity, and chemical interactions with sisal and plaster over that time would likely lead to significant DNA degradation. Even if mtDNA can be extracted, the DNA might be highly fragmented, reducing the quantity and quality of genetic information available for analysis.
- Impact
of Embalming:
- Chemical
Challenges: Embalming involves the use of chemicals, particularly
formaldehyde, which can severely impact DNA. Formaldehyde causes
cross-linking of DNA strands, making the DNA more difficult to extract
and analyze. Over time, this chemical treatment can lead to significant
degradation, reducing the overall yield and quality of DNA available for
forensic analysis.
- Fragmentation
and Yield: The DNA recovered from embalmed bodies is often fragmented
and available in much smaller quantities. This further complicates the
use of imputation, as the degraded and cross-linked DNA might be
insufficient for reliable imputation.
- Specialized
Techniques Required: Recovering DNA from embalmed bodies requires
advanced extraction techniques that can address the challenges posed by
chemical cross-linking. While some mtDNA may still be recoverable, the
overall process is more complex and less likely to yield a complete
genetic profile.
Given these additional challenges, imputation would likely
produce unreliable results, if any results at all. The degraded and chemically
altered DNA would limit the effectiveness of imputation, making any forensic
conclusions based on such an analysis highly uncertain.
Final Considerations: Lack of Transparency in Sample
Retrieval
An important detail that further complicates the analysis is
the lack of transparency regarding the rootless hair shaft used in the
analysis. No clear information has been provided about where or when the hair
sample was found, nor about the method used to retrieve it or the person who
handled its collection.
This lack of documentation and transparency raises concerns
about the chain of custody and the integrity of the sample. In forensic
science, the chain of custody is crucial to ensure that the evidence has not
been tampered with or contaminated. Without this critical information, the
reliability of the DNA analysis is further compromised, casting additional
doubt on the conclusion that Carl Webb was the Somerton Man.
Conclusion: The Power and Limits of DNA Evidence
DNA evidence is a powerful tool in forensic science, capable
of solving cases and providing closure to mysteries. However, understanding the
differences between nuclear and mitochondrial DNA, the role of techniques like
imputation, and the impact of environmental factors and chemical treatments
like embalming is crucial for accurately interpreting this evidence. In cases
like the Somerton Man, where the available DNA is limited and potentially
compromised, it’s important to recognize the limitations and proceed with
caution.
Additionally, the lack of transparency regarding the retrieval and handling of the hair sample adds another layer of uncertainty, emphasizing the need for careful consideration before drawing any definitive conclusions. By understanding these concepts, we can better appreciate the complexities of forensic investigations and the science that drives them. Whether you’re watching a true crime show or following a real-life case, knowing how DNA evidence works—and its limitations—can provide deeper insights into the pursuit of justice.
After considering all the gathered information, including
the use of mtDNA, the challenges posed by degraded and chemically treated
samples, the limitations of DNA imputation, and the concerns about the chain of
custody, I would finalize the estimate of the likelihood of Carl Webb being the
Somerton Man at around 15-20%.
This final estimate reflects the compounded uncertainties
and the significant limitations of the evidence available. While there is still
some possibility, the cumulative impact of these factors substantially reduces
the confidence in the identification.
And there you have it. It's worthy of note that I did not include the issue of the use of mortuary soap by Mr'Paul Lawson to slick down the hair on the man's head with such soap containing sodium hypochlorite, it would have destroyed any DNA that it came into contact with. Neither did I take into account the significant difference in the physical appearance of the Somerton Man and Carl Webb as well as the height variation that was calculated from the use of known dimensions in the image of Carl Webb. Even as it is, without those aspects taken into account, the analysis made by AI is clear in its conclusion, there is a very low, 25% likelihood that Carl Webb was the Somerton Man.
Of course, this analysis should be carefully read through and those with the necessary knowledge can test out the assertions and conclusions made. Perhaps even use the same data with a different but substantial AI tool set?
We now know who the Somerton Man isn't. Will it be possible to find out who he is? TIme will tell.
A final note from me, I will not be posting here for a little while, I have much work to do related to the completion of the book which I have undertaken to do prior to Christmas this year.
Didn't the professor post about someone from Adelaide University collecting the hair samples? I am sure there were photographs of a young woman and another of a man taking the samples.
ReplyDeleteThat's correct, there was a mention of others collecting samples, BUT, they were the earlier samples that showed up either negative or just plain poor quality. Enough to be able to detect metals etc but not enough or in fact none in the way of DNA. That person was Janet Edson and the year was 2015. The rootless hair sample was subject of an article in the IEEE magazine, of which Professor Abbot is the editor in chief. It does not mention where or when the rootless shaft was taken as a sample nor who took it and what process was used to extract and then keep it. Here's the only reference to the shaft:
ReplyDelete"Seemingly out of options, we tried a desperate move. We asked Astrea to analyze a 5-centimeter-long shaft of hair that had no root at all. Bang! The company retrieved 2 million SNPs. The identity of the Somerton Man was now within our reach."
No mention of when, where or who or the methods/processes used. Here's the link to the IEE article:
https://spectrum.ieee.org/somerton-man
In other words it is totally unsubstantiated.
Hope this helps.
This is the calibre of material we need, credit where it's due, every post you put out is loaded with facts and details and most of it new. It's a high standard that you've set yourself, keep it up! Looking forward to the book if it's anything like this, when's it due?
ReplyDeleteThanks for the compliment! It takes a lot longer to bring together but it's worth it in the end. This one's been in the works for some weeks on and off. Writing every day and aiming for that pre Christmas release. I am making every effort to include as much new material and new insights as I can. This post will be the last for a while, such a lot of work ahead of me but I'm enjoying every minute of it.
ReplyDeleteLiked the charts, explains the differences between the root and rootless shaft really well. There's good value in that progressive chart as well with the different aspects affecting the likelihood, simple and easy to understand. The whole Webb claim systematically deconstructed and all the weaknesses are out on full display, I take the point that this will be unpalatable for some.
ReplyDeleteWhat's the significance of mortuary soap? How much hypochlorite does of have to have to knock out DNA?
ReplyDeleteGood question, its green in colour or used to be and it smells foul. The Hypo % I think needs to be around 12% or more, some of it was 20%. In those days it wasn't about DNA of course just some of the nasty stuff that tends to exist around corpses or where they'd been. But the reality is that unknown to the medicos at the time, one side effect of Hypochlorite was that it kills DNA, it's so good at it that the various DNA labs use it to clean all their surfaces because it eliminates any source of potential contamination.
ReplyDeleteS'Mai Wass! OK, I've read that post and it looks good but what if the AI is hallucinating? It can do that can't it?
ReplyDeletethe short answer is Yes, AI models can 'hallucinate' in some circumstances. It's a problem faced by all AI tools so what you have to do is to verify the information it provides and to the best of my ability, I have done that. But you're quite right to bring it up, it's important and its relevant. Check it out for yourself by googling anyone of the responses and statements made by the AI tool I used. I might have missed one so it's always worth checking. That's one of the reasons preparing complex posts can take so long. Oh, nearly forgot, Iawn Diolch, Sut yr udydd chi? Not bad for a Paddy :)
ReplyDeleteHell, that ear's a whole lot different, can't see that being the same bloke.
ReplyDeleteMichael, the ear has always been a problem in this case. One of the earlier claims made was that it was an unusual ear shape but that was disproved here nd in fact prior to that when I was involved with the eraly FB page hosted by Adelaide University back in 2009 or 2010? I was able to show that one of Jess's grandchildren, whose mother cam along after SMs time, had exactly the same ear as him. But in this case you can see the ear shape for young Carl and the somewhat older Carl both being the same, tapered shape. Not the case for the Somerton Man's ear, it is 'squatter' in appearance and definitely not tapered. One argument out forward is that our ears change as we grow older. That's true but the change is that the lobe lengthens, not the inner helix and it is also true that these changes start to appear after 40 years of age and that's when the ear lobe starts to lengthen by approximately .2 mm every year. So that 'ear idea' that suggests all kinds of changes happen is clearly wrong.
ReplyDeleteOff line for a little while guys, apologies!
ReplyDeleteThe photo is pretty telling,. The two to the right of Carl are similar especially the ears but the far left pic of TSM is really different. Wonder what effect that would have if AI factored it into the likelihood bar chart. 0%?
ReplyDeleteWhen did you first post about the hair shaft GC?
ReplyDeleteThe first time was in August 22, why do you ask? No, don’t tell me, I think I know the answer. Can’t help himself. Karma’s a wonderful thing :)
ReplyDeleteIt's well known that all the ciphermysteries and tomsBT blogs do is to rehash your posts. I haven't seen anything original on the TBT blog or CM for that matter for years. As for the other site, abuse, more abuse and hijacking your material is all its good for. I've messaged you before about this but you didn't post it. I hope you do that this time. People need to know
ReplyDeleteI think the saying 'He who slings mud is losing ground', seems to fit the bill. But let's get on with the task at hand, the search for truth.
ReplyDelete