SciBlogs

Archive November 2009

Peek-a-boo: Monarch butterfly chrysalides Anna Sandiford Nov 30

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Although not strictly forensic science, these Monarch butterfly caterpillars preparing for life as a butterfly are just too good to ignore. It fascinates me how they manage to produce gold decorations – I can only assume they extract the gold from the plant? Is it even gold?  (Apologies for the red date stamp).


There are three chrysalides in the first photo, relatively easy to see.


There are seven hiding in the middle photo – can you spot them all?!

The last photo is  slightly out of focus but it’s neat to see the before and after stages so close to one another. I just hope some of the dozen or so chrysalides littering the plant and proximally located potato plants actually survive. Last year we had 100% failure rate.

Justification for the existence of vampires Anna Sandiford Nov 27

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Given that it’s Friday, I think a bit of light scientific relief is in order.

As anyone who has anything to do with teenagers (particularly girls) will know, Vampires are the new Black.  As teenagers are wont to do, they spend much time frightening themselves with the idea that vampires are indeed real and are ready to swoop down and get us all whilst we sleep.

Fortunately for us all, Fox News has devoted time, energy and presumably money in investigating the science behind the myth that is the Vampire.  The opening of the article Are Vampires Real? The Science Behind the Myth demonstrates to us the basis for the development of the myth:  “Decomposing bodies that leaked blood must have frightened gravediggers in the past. Tropical diseases and insects that suck blood, leaving corpses wasted and desiccated, must have seemed scary to other cultures. It’s a short jump from fearful to superstitious, and there are clear biological and anthropological conditions that likely led to these fears.”

Fox News’s intrepid reporters have then investigated the mainstays of vampire life:

  • avoiding sunlight – porphyria or allergy to sunlight or, more commonly, polymorphic light eruption – an immune response to sunlight,
  • immortality  – apparently the activity of the telomerase enzyme in certain of our cell structures can extended the life of those cells – a chemical in our cells that may hold the secret to eternal youth, which may explain how vampires can live forever
  • drinking blood – possibly related to anaemia

There’s no mention of the Holy water or silver bullet issues – bullets of any kind are pretty definitive and many people would shy away from water being thrown at them, Holy or otherwise (although I can think of a few who’d run a mile at the Holy issue).

To debunk the possibility of vampires taking over the world, a paper has been written by physicists C Efthimiou and S Gandhi (meaning someone probably had funding for this) that details a mathematical formula to describe the number of humans left after x months of vampirism spreading through a population of a theoretical size (Skeptical Inquirer v. 31, issue 4 (2007), p. 27).  Apparently, if, as legend has it, the first vampire appeared in 1600 AD, the human population would have been decimated within 2 and a half years.  Their concluding remark is that  “vampires cannot exist, since their existence contradicts the existence of human beings. Incidentally, the logical proof that we just presented is of a type known as reduction ad absurdum, that is, reduction to the absurd” – how many times an a scientist say that during their research career (or maybe I’m just in the wrong sort of science)?

So next time you have to manage a teenage nightmare or you get drawn into an endless teenage discussion about vampires, you’ll be able to settle their minds with ease.

Excellent Book 2: Stiff: the curious lives of human cadavers Anna Sandiford Nov 25

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Following my currently somewhat morbid theme of human death, putrefaction and skeletonisation (see Death’s Acre: Beyond the Legendary Body Farm by Bill Bass), I have just finished reading another jolly night-time book. It’s called Stiff: the curious lives of human cadavers by Mary Roach (2004, Penguin, 304 pp).

The author presents an absorbing set of tales about what happens to the human body after it has been gifted to research. Again, it might not be for the squeamish but we’re scientists, so it’s no problem!
Each chapter is devoted to a different area of research, whether it be early anatomists, crash test cadavers (or parts thereof), development of land-mine boots, assessing the Shroud of Turin, whether or not a corpse is dead and the “live” removal of organs from a brain-dead but still-beating-heart person. My personal favourite was the opening chapter about reconstructive surgery and practicing facelifts on severed heads that yesterday had had rhinoplasty – oh, the irony of someone who had always wanted a nose job but didn’t get to have one when they were alive but gets the nip/tuck works after they’ve donated their body to medical research.  Plus think of the money they saved.

I enjoyed this book because it is written by a non-medic – she’s just an interested party who now has some amazing tales to tell at parties (although from experience I would suggest that she will have learnt quickly that one needs to assess one’s audience before launching into the details of a post-mortem).

I thoroughly recommend this book.  It’s the sort of book that can be read a chapter at a time whilst maintaining more traditional fiction books in between times.  The only problems is that at bedtime when you’re trying to distract your brain, slow it down and lull it to sleep, this book wakes it up with its interesting detail and insights into what really happens to medical research cadavers.  Will I be leaving my body to medical research?  I’m still thinking about it…..

Nifty forensic science techniques – real CSI Anna Sandiford Nov 24

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How to remove a lightbulb using a kid’s dart is described as “a high tech process to remove a light bulb without damaging latent prints using a toy dart” (some dry humour is always a good thing in forensic science) – this is the sort of forensic technique that is not only interesting but extremely useful….and it’s exactly how it sounds!

Other useful videos on the same page include How to lift a dusted fingerprint off a body or a live person and How to use a stun gun as an electrostatic dust lifter. These videos are short and highly informative. Recommended viewing for the interested and the budding crime scene investigator.

Forensic DNA resource Anna Sandiford Nov 20

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I often receive queries about forensic DNA – how to get a job, how it works, what it’s all about.  As a result, I have trawled about the web quite a lot and encountered The DNA Initiative. It’s an American website, so some things are not immediately applicable to other countries (such as Statues and case law, but they’re still interesting).  Overall ,it seems to be a comprehensive site that explains all about forensic DNA including how it can be applied in Cold Case Reviews.

Part 3: CSI effect/forensic science jobs Anna Sandiford Nov 20

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I have previously talked about how to get a job in forensic science and how CSI has skewed the image the general public has of forensic scientists (see job in forensic science, retrain, real CSI effect, speed and effect of science, job in forensic science plus others – it’s something about which I have strong feelings…). This is a good and brief article dealing with Bob Shaler’s opinion on forensic science, CSI and what it means to get a job in forensic science: Is Forensic Science on TV Accurate?. Bob Shaler was the man charged with handling the DNA identification of the World Trade Centre bombings so he knows his stuff. Disappointingly for many, when he says “I was a crime lab guy, but I was never the person portrayed on TV.” “That person doesn’t really exist.” – it’s sad but true.

Pollen, pooh and the extinction of mammoths Anna Sandiford Nov 20

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One of my work-heads is as a Palynologist, which means I study pollen, spores and other microscopic material that remain in sediments after they’ve been chemically treated to remove extraneous material.  For forensic work, we might be limited to sediment scraped from the knee of a pair of trousers or perhaps pollen collected from the heads of cannabis plants, but any sort of sediment can be examined for pollen.
For geological/archaeological samples, lake sediments and peats are the best in terms of preservation state, abundance and variety.  It is therefore extremely heartening to see that palynology has been able to help in determining the extinction mechanism of mammoths and other large mammals during the last Ice Age, which ended approximately 10,000 years ago (depending on one’s global location) – see Mammoth dung unravels extinction. The study indicates a gradual decline in large mammal numbers, not a catastrophic extinction a la the dinosaurs at the Cretaceous-Tertiary boundary 65 million years ago.
Scientifically, it’s an interesting study but from a general perspective I still find it strange that people are surprised that the large mammals are probably more than just a pretty addition to an African landscape but have actually been significant in it’s development. I’m pretty sure David Attenborough’s known that for years.
It’s also reassuring that analysing excrement can add so much information to our knowledge – an archaeologist I know has spent years analysing coprolites from Maori sites. It’s fascinating what we can learn from pooh.

Excellent book: Death’s Acre – Beyond the Body Farm Anna Sandiford Nov 19

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What happens to the human body after it dies? Well, after the TV program two nights ago about what happens to bodies when they are gifted to research, it’s been possible to get a visual insight into the ‘after life’. If your stomach’s not up to it or you can’t stand the smell, “Death’s Acre, Beyond the Legendary Body Farm” by Bill Bass & Jon Jefferson is an excellent read. It’s largely autobiographical in that it’s written by the man who founded the Body Farm (to whom and to which I have referred in an earlier post) and it’s an extremely insight book into the world of forensic anthropology.
Dr Bill Bass established the Body Farm in 1980 – it’s now a major research facility dealing with how the human body decomposes under different circumstances after death (locked in the boot of a car in hot weather or cold weather; how long bodies stay submerged in water; what happens if a body lies on a coin for twelve days…the possibilities are endless because the circumstances of casework are endless) – it’s the only facility of it’s kind in the world – probably because no-one else wants rotting corpses lying around in the open air. Fascinating reading and not gory at all (well, not my most forensic science book standards….).
He provides interesting case examples and hasn’t been afraid to admit where his knowledge was lacking in the early days and why, therefore, considerable research was required to bring the subject to the high level it now enjoys.
Dr Bass writes in a clear and enjoyable way – he’s one of those writers who can convey a difficult and somewhat morbid day job into a fascinating learning experience for the reader. I love reading books like this because I always come away having learnt something new – and doing that without having to read a dry text book is a plus as far as I’m concerned. Plus his story about being told off by his wife for boiling up bodies on the kitchen stove makes me feel less guilty about wrecking expensive household items during a recent research project…

Blood pattern analysis – how to get started! Anna Sandiford Nov 18

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Blood pattern analysis (BPA) is an area of forensic science that is extremely important but extremely under-rated – people seem to have a misconception about how easy it is to “read” blood patterns (no doubt not helped by CSI!).  To become proficient in blood pattern analysis requires more than just a few tests drips cast down a wall or onto paper.  Understanding the variability in pattern (or lack of) created by direction, velocity, flow, depositional surface…. are crucial to correct interpretation of blood patterns.  As with any other area of forensic science, specialised training is required plus considerable experience backed up with advice and peer-review.  It’s not the sort of thing that can just be Googled for a quick answer.

Finally I have managed to find a good online resource that details how to record blood patterns: Documenting Bloodstain Patterns Through Roadmapping .  It may sound ridiculous but you’d be amazed at how poorly blood patterns are recorded in casework. As the article states, “As the old adage goes, “a picture is worth a thousand words.” However, in the field of crime scene investigation this saying should be changed to “a properly taken picture is worth a thousand words.” Never is this more true than when documenting bloodstain patterns at a scene. Proper documentation of a crime scene, and bloodstains specifically, verifies the integrity of the scene and the evidence within it; provides quality presentations for subsequent courtroom testimony; and allows for outside analysis by other experts. The fundamental goal of documenting bloodstain patterns is to accurately depict the patterns as you found them.” One of the key indicators of a good crime scene examiner is the ability to record information from a crime scene so that it can be viewed at a later date by individuals who have not attended the crime scene so that they, in turn, will be able to understand what was present and, if necessary,re-interpret the patterns.  Some people could learn from this….

Is this the world’s slowest lab turned around time?! Anna Sandiford Nov 13

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A man in Trinidad and Tobago had to wait six years for his trial to be heard – he was arrested for possession of a pistol and six rounds of ammunition in September 2003 – Man freed after six-year trial. The firearm and bullets were sent to the Forensic Science Centre on 26 September 2003 and the Certificate of Analysis was dated 15 February 2007 – a total of 3 and a half years…but what have they been doing since then that delayed the final verdict?!  The article is silent on that point.

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