Rewriting the History of the Black Plague

We’ve discussed the history and science behind the Black Death several times already on Skeleton Keys—from bubonic plague victims discovered in London, to a cemetery under a Parisian supermarket, to whether rats were truly responsible for spreading the epidemic, to the 15^th century Bedlam hospital cemetery that was recently unearthed, and finally to sequencing Yersinia pestis, the bug that caused the disease. But the plague was back in the news again last week with the announcement of the discovery of Bronze Age skeletons containing DNA from Y. pestis, indicating the existence of the plague a full 3,000 years earlier than originally suspected.

While the most well-known instance of plague is the 14^th century Black Death epidemic that ravaged Europe and killed more than half the population (approximately 50 million people), the earliest known epidemic was in 6^th century Germany. And while theories hold that the ancient Greeks also experienced plague, there is no scientific proof of its existence in that population.

The Bronze Age is known as being a time of not only the development of much stronger bronze tools by smelting copper with tin and other metals, but also the development of early writing systems and the first structured (though early) civilizations. It is also known as the time of a sudden mass migration from Russia and modern day Ukraine into Europe. Scientists now think they can explain why.

DNA extracted from the teeth of 101 Bronze Age skeletons was sequenced in hopes of finding traces of Y. pestis as a method of explaining the mass exodus. To their surprise, a significant number of specimens (7%, which is high as a single cause of illness-based death in a normal general population) contained Y. pestis sequences, and two specimens contained sufficient DNA to encode the entire Y. pestis genome. The oldest strains dated back to 3,000 B.C., a full three millennia before previously theorized plague origins.

When scientists studied the stains of Bronze Age Y. pestis and compared it to the deadly 14^th century version, they found an interesting evolutionary tale. The earliest versions of the plague bacteria lacked the gene that enables the bacteria to colonize the gut of fleas which enables them to be the vector between human hosts. Without that insect vector, Y. pestis could only be spread human-to-human directly through blood or saliva, and, as such, was much less transmissible. However, by 1,000 B.C., that gene was present in the bacteria allowing for zoonotic (animal/insect to human) transfer and increased rates of infection. These same early Bronze Age versions of the plague contained another gene, one that allowed the bacteria to infect the lungs of humans. As a result, Bronze Age Y. pestis likely caused pneumonic plague rather than bubonic plague (an infection of the lymphatic system). This was by no means a preferable version of the disease—while infections were less common, the death rate from pneumonic plague was 90 - 100%, as opposed to bubonic plague’s 30 – 90%.

Such a catastrophic death rate supports the theory that a mass migration occurred in an effort to escape the ravages of the disease. Without the advantage of transmission and transport via fleas—which would use other animals to move from place to place, often in the company of potential human hosts—Bronze Age people could successfully escape the disease by traveling into Europe. DNA studies of Europeans have previously confirmed a shift in genetic makeup from typical European hunter gatherers in 3,000 B.C. toward the Yamnaya phenotype typical of the Russian/Ukrainian area, around 2,000 B.C.

Photo credit: Nature

Forensics 101: A New Technique to Pinpoint Time Since Death

One of the very first forensics posts on Skeleton Keys was about using decomposition to pinpoint the time since death for fleshed bodies. As we mentioned back then, there are some fairly precise ways to measure time since death in first hours following death, up until 24—48 hours post-mortem. But after that, things are much less exact. Needless to say, this can be a problem for investigators who are trying to pin down suspects who need to substantiate their whereabouts with an alibi. But if the best you can do is a 24 hour period, it can be hard for even an innocent person to list all their movements. And what if the investigators are looking at the wrong 24 hour period due to an inaccurate estimate? A more precise way to identify time since death after the immediate post-mortem period would be a welcome tool for investigators.

A team of researchers who recently published in Toxicology Research may have an answer to this dilemma. Their original study set out to examine the changes in 46 biochemical blood parameters to develop a reliable mathematical model to determine time since death. Using 20 normal human blood samples, drawn, aliquotted, and left to coagulate normally, they temperature controlled blood cooling to mimic the typical drop in human body temperature after death—from 37^oC to 21^oC, decreasing 0.5^oC per hour. They then started a kinetic (in time) analysis of the properties of the blood including pH measurements, protein, lipid, enzyme, and electrolyte levels and activity. Of the 46 parameters, ­­­­10 were found to be statistically significant in estimating time since death: total and direct bilirubin, urea, uric acid, transferrin, immunoglobulin M, creatine kinase, aspartate aminotransferase, calcium, and iron. Using these markers, researchers suggest that investigators and forensic scientists will be able to much more precisely pinpoint the time of death out to 11 days after death.

While the results are promising, the authors outline future areas of study as these experiments were done in vitro (outside the body) and under very controlled circumstances. Samples from deceased individuals of known time must also be studied for corroboration. In addition, multiple variables must be considered such as age, gender, body mass, cause of death, and length and type of stress at the time of death. External factors may also play a part—environment and temperature, humidity or precipitation, clothing, or whether the body is buried or left out in the open and possibly infested with insects or consumed by animals. So while there is a lot of research still to do, it’s definitely a very solid starting point from which to launch further research opportunities. Perhaps in a few years, investigators will have a dependable way to identify the time of death of individuals, making their search for suspects a more informed process, hopefully leading to better conviction rates.

Photo credit: Costa et al. in Toxicology Research

Forensic Case Files: West Port Murders

It’s been a while since we did a Forensic Case Files post, so I thought it was time to delve back into history to look at a fascinating case, one that I was unfamiliar with until one of our amazing street team readers made a comment in a blog post a few months back. When she read the blurb for LAMENT THE COMMON BONES, she commented that it was like shades of Burke and Hare, to which I said Who? I have no idea why I’d never heard this story because it’s a doozy.

Back in the early nineteenth century, medical science was advancing in leaps and bounds. But one aspect that held this burgeoning science back was the lack of autopsy specimens to use for dissections, both to explore the human body and to teach new medical students. Edinburgh, Scotland was a European hotbed of medical advances. Doctors were using cadavers from convict executions, but due to changes in the legal system of the time, fewer executions were occurring, leaving doctors shorthanded. One particular doctor, Robert Knox, took to paying for cadavers that were acquired for him outside the usual system. Many of these cadavers came from grave robbing, giving rise to the name for these body snatchers as ‘resurrectionists’. It got so bad in the 1820s that loved ones of the recently deceased took to hiring guards to watch over the newly buried dead until they had decomposed to an extent that they would not be useful in a dissection.

William Burke and William Hare found another way around this problem. Burke and Hare met as labourers working at the Union Canal. However, the lynchpin in what would become a significant killing spree was that Hare’s wife, Margaret, ran a lodging house for beggars in Edinburgh. It was owned by Margaret and her first husband, Logue, but when Logue died, and she married Hare, Margaret continued as landlady.

Burke and Hare’s life of crime started innocently enough. One of the lodgers died of natural causes while living at the house and still owning rent to Margaret. So Burke and Hare sold his body to Dr. Knox to recoup some of the lost monies. Dr. Knox, a surgeon from the Battle of Waterloo, gave public lectures, charging each of the up to four hundred attendees to attend. So Dr. Knox had a vested interest in ensuring he had sufficient cadavers to sustain his lecture series and his livelihood. It was well worth his seven pounds, ten shillings for a fresh cadaver. At a current value of approximately $1300, Burke and Hare were hooked.

At first they started murdering ill tenants in the boarding house by intoxicating and then suffocating them, a tactic later termed ‘burking’. When they ran out of tenants, they moved onto the homeless, the destitute and prostitutes, luring them into the lodging house, killing them and removing them from the premises in a tea chest. If it was not immediately convenient to move the body to the tea chest, they would often leave the victim under a bed in the room in which the murder took place. In the end, it was this practice that was their undoing.

A couple returned to the lodging house, the wife claiming to have left a pair of stockings behind. When she returned to her old room, she found the body of Mary Docherty, the final victim, under the bed. A ten pound bribe was offered to silence the couple, but they refused and reported the incident to the police. In all, sixteen victims died at the hands of Burke and Hare before they were caught.

Burke and Hare were imprisoned and the case went to trial on shaky grounds. For starters, only one body was recovered, the rest were all lost to medical dissections. And examiners could not definitively determine the cause of Mary Docherty’s cause of death. But Burke had made a fatal mistake—while they usually discarded the victims’ clothes into the Union Canal, Burke took the clothes of a young male victim and passed them onto his nephews, leaving later evidence for the prosecution. But the trial turned when Hare gave evidence against Burke in exchange for immunity from prosecution, leading to Burke’s conviction and eventual execution.

William Burke was hanged on January 28, 1829, and then his body was publically dissected. His skeleton still hangs today in the Anatomy Museum of the Edinburgh Medical School, and a book cover, a number of wallets, and a calling card case were made from his tanned skin. The book now resides in the Surgeon’s Museum, along with Burke’s death mask and a live cast of Hare’s face.

William Hare was released from prison in February of 1829 and made his way to Dumfries where he was instantly recognized, which started a riot. He was removed from town and left on a major road with instructions to strike out for the English border. He was seen two days later two miles south of Carlisle. There is no dependable record of his existence after that.

Dr. Knox, the medical doctor whose need for cadavers started Burke and Hare down the road to murder, was found guilty in the public eye of inciting the murders. This resulted in a Scottish mob throwing stones at his house, and then hanging and burning him in effigy. Knox remained in Edinburgh, giving his lecture series until the 1840s, before moving to London to finish out his life’s working as an anatomist at Brompton Hospital.

Recent Advances in Fingerprinting

While we were on writing hiatus over the summer, several stories made the news concerning advances in the forensic field of fingerprinting. Since they included several new techniques, I thought it would be good to cover them in a single post here on Skeleton Keys, where we always try to stay up to date with the newest in forensics.

Fingerprinting involves identifying an individual by their unique pattern of arches, loops, and whorls on the ridges of the fingertips. Invisible oils and other biomolecules are laid down on a surface, and crime scene techs visualize those scant traces through a number of methods. Those prints are then compared to a local, national or international database and, hopefully, a match is made and a perpetrator is identified.

But a person’s identity may not be the only thing revealed by his fingerprints, as was recently announced:

1. Determining the use of illegal drugs: Researchers from the University of Surrey in England have developed a method to test the residue left in a fingerprint for cocaine using mass spectrometry. More importantly, based on the drug metabolites, it can be determined whether the cocaine was ingested, or whether the suspect simply touched it and traces of the drug remained on his fingertips. New portable mass spectrometers are being developed to make this a technique that can be used in the field at actual crime scenes.
2. Fingerprint Molecular Identification (FMI) technology to identify gender, narcotics and nicotine: North Carolina’s ArroGen Group has developed FMI technology, again using mass spectrometry, to identify gender biomarkers, as well as metabolites of nicotine, heroin, methamphetamine, marijuana, temazepam, ecstasy and even some legal medications. This panel of distinctive chemical substances could lead to suspect identification as well as criminal convictions.
3. Determining the age of a fingerprint: Researchers at the National Institute of Standards and Technology have developed a method to approximate the age of a fingerprint. This has always been a problem using fingerprints as criminal evidence—a print might prove an individual was in a particular location, or touched a particular object, but was it at the time of a crime, or the week before and therefore possibly insignificant? Scientists have tried to develop a method to date fingerprints based on the breakdown of the biochemical products in the fingerprint, but to no avail. However this method is different and depends on the movement of biomolecules from the ridge to the empty valley sections of the print. Essentially the clearly defined lines in a fresh print will blur and become indistinct with time. How much so will help scientists date an individual print. So far, scientists have been able to distinguish between a day and a week old, a week and a month old, and a month and four months old. This is still a proof-of-concept method, but researchers are working to fine tune the technique, which could be incredibly useful in criminal investigations.
4. Determining race of an individual: We’ve previously discussed how to determine race from a victim’s skull, but researchers from North Carolina State University recently announced a technique to determine race from the minutiae of the fingerprint. In a nutshell, there are three levels of examination for a fingerprint. The first level is the one most people are familiar with—those ridge formations called arches, loops, and whorls shown in a standard ink print. The second level is the minutiae—the deviations of those arches, loops, and whorls—where a ridge ends, when it splits in two at a bifurcation, or where the ridge makes a U-turn in a loop or whorl. In comparing those from African-American and European-American backgrounds, researchers found significant differences at the minutiae level, enough to be able to determine from which group the individual came. The study only involved 243 subjects, so these are very preliminary results, but so far the data appears promising.

It is early days so far for many of these techniques, but, with additional study, hopefully they will develop into full-fledged tools for investigators, providing them with more information and hopefully leading to more definitive suspect and victim identifications.

Photo credit: Wikimedia Commons