Human teeth play a key role in our understanding of how organisms evolve. Whenever a possible new member of the hominid family is uncovered, the shape and number of teeth are used to place that individual in the family tree. Teeth also harbor information about pathogens that have plagued humans for millennia. Because bacteria use our bloodstream as a transport system, protected places that can preserve DNA—like the pulp of teeth—are a rich medium for uncovering information about humans and the microbes that infected them.
Teeth have been the choice for identifying the infectious agent behind the Plague of Justinian in the sixth century and the Black Plague in the 14th century. In fact, Yersinia pestis, the bacterium responsible for these plagues, has infected humans as far back as the Neolithic. But what can we learn about the pandemic strain or strains of Y. pestis described in historical records? A team of researchers from Europe and the US, many of whom have been delving into the history of Y. pestis for the last decade, wanted to further investigate the Plague of Justinian. They studied bacterial DNA extracted from human remains found in Western European communal graves that were dated to around 541–750, the period of the historically documented Plague of Justinian. Their investigation examined the bacteria’s diversity and how far it spread during this “First Pandemic” of plague. Continue reading “Delving into the Diversity of The Plague of Justinian”
In recent years, scientists have been able to refine their molecular tools to resurrect ancient DNA from human graves and determine that yes, Yersinia pestis was the causative agent for the Black Death in the 14th century and the Plague of Justinian in the 6th century. As more and more human graves have been uncovered, their DNA has revealed many secrets that scientists even ten years ago were unable to discover. With the ability to sequence entire genomes of bacteria that died with their hosts hundreds and even thousands of years ago, researchers are exploring the rise and possible spread of Y. pestis. Each new member sequence adds to the Y. pestis family tree, pinpointing the origin of this bacteria as it diverged from its ancestor Y. pseudotuberculosis. Peering into the past, scientists have been able to track down a strain of Y. pestis from individuals in a Swedish passage grave that is basal to known strains and that the authors of a Cell article suggest has interesting implications.
This pathogenic journey into history started by analyzing ancient DNA data sets from the teeth of individuals present in a communal passage grave in Gökhem parish, located in western Sweden, for any disease-causing microbial sequences that might be present. Y. pestis was flagged in one 20-year-old female dated 4,867–5,040 years ago. The bacterial sequences from this individual, named Gok2, were more closely aligned with Y. pestis than the Y. pseudotuberculosis reference genome. Continue reading “Expanding the Plague Family Tree: Yersinia pestis in the Neolithic”
In February 2018 we wrote about a resurrection effort to bring the then endangered black-footed ferret back from the brink of extinction in western U.S. This effort was undertaken by the U.S. Fish and Wildlife Service, with assistance from Revive & Restore and partners ViaGen Pets & Equine, San Diego Zoo Global and the Association of Zoos and Aquariums. On February 18, the U.S. Fish and Wildlife Service announced announced the successful cloning of a black-footed ferret, introducing the world to a 38-day-old black-footed ferret kit “Elizabeth Ann” cloned from cells of a female ferret that died in 1988.
Cells from ferret, “Willa” were preserved by freezing, and when somatic cell nuclear transfer (SCNT) became a possibility, Willa’s cells were used to create Elizabeth Ann, the kit born just over one month ago.
Before Elizabeth Ann’s birth there were upwards of 1,000 black-footed ferrets alive in the western U.S., but they were all descendants of just 7 ferrets, and thus genetically very similar.
Analysis of Elizabeth Ann’s genome has revealed more than three times the genetic variants found in the existing wild U.S. ferrets. This means that if she is able to reproduce, her contribution to the genetic diversity of wild ferrets would be huge.
Interested in learning more about ferrets and the challenges they’ve faced in surviving and thriving in the wild? Below is our original 2018 blog with those details. Don’t miss the video clip of a young black-footed ferret doing the “weasel war dance” (below).
My last blog post on the Black Death highlighted research that suggested that the reintroduction of Yersinia pestis, the causative agent of the pandemic, originated in Europe during the 14–18th centuries rather than from Asia, the hypothesized origin. In my post, I wrote about my curiosity regarding what an Asian skeleton positive for Y. pestis from that same time period would reveal about the strain or strains that were circulating. Well, a team of researchers has been exploring the issue of strain circulation and an Asian connection, and recently published what they gleaned from additional historic Y. pestis samples in Cell Host & Microbe.
In the last six years, researchers have untangled the origins of devastating human plagues, sequenced the genome of a Yersinia pestis strain responsible for the Black Death and explored how long this bacterium has been with humans. However, the information arising from this research begs more questions. How many variations of Y. pestis occurred during the 14–17th centuries, the second pandemic that began with the Black Death? Did these differences reflect the location in which the Y. pestis-positive skeletons were found? What were the geographic source or sources of these plagues? A recent PLOS ONE article examined Y. pestis found in German remains separated by 500km and 300 years to answer to some of these questions. Continue reading “The Black Death: World Traveler or Persistent Homebody?”
Fridays are generally reserved for fun posts to share prior to the weekend. As we all know, fun is relative and to me, the latest news about how long Yersinia pestis has been entwined with human history is intriguing. I enjoy writing about the latest historical finding of Y. pestis even if I do earn a black reputation among my blogging colleagues (pun intended). Therefore, as soon as I saw the Cell article about Y. pestis found in Bronze age human teeth, I knew my blog topic was at hand.
Y. pestis has long been suspected in several plagues that occurred in the last two millennia. Publications in 2011 and 2013 used DNA extracted from teeth of human remains dated to the 14th century Black Death and 6th century Plague of Justinian to confirm Y. pestis was the causative agent in those devastating plagues. These results beg the question: How long has Y. pestis been infecting humans? The phylogenic trees generated from recent studies suggested Y. pestis has been with humans for as little as 2,600 years and as long as and 28,000 years. Equipped with these DNA-based tools, Rasmussen et al. asked if they could find evidence of Y. pestis in older human remains. Continue reading “Yersinia pestis Reveals More Secrets From the Grave”
American national parks have spectacular scenery enjoyed by hikers worldwide. It’s one way people can enjoy some of the preserved wild places in North America. Due to this intersection of humans and wild animals, a bacterium that is endemic to the southwestern United States has infected a few humans after trips to Yosemite National Park, sparking many news headlines about the plague and closure of a few camping sites for chemical treatment to reduce local flea populations. In total, this summer has seen six cases of infection and unfortunately, three deaths from the plague. Continue reading “The Intersection of Plague and National Parks”
Writing about Yersinia pestis or the Black Death, has earned me a reputation among Promega Connections bloggers. I am interested in what researchers have been able to piece together about the causative agent of ancient plagues, what modern research shows about how Y. pestis spreads in the body and the continuing reservoirs in modern times, resulting in publication of eight blog posts on the subject. Understanding Y. pestis bacterium is of continuing interest to researchers. How did Yersinia pestis evolve from the humble Yersinia pseudotuberculosis, a pathogen that causes gastrointestinal distress, into a virulent pneumonic plague that is a global killer? One strategy for answering this question is to look at the genomic tree of Y. pestis and trace which strains had what characteristics. In a recent Nature Communications article, Zimbler et al. explored the role of the plasmid pPCP1 in Y. pestis evolution and the signature protease Pla it expresses. Continue reading “All You Need is Pla (for Pneumonic Plague)”
Understanding the course of a pathogenic infection involves not only understanding what ultimately kills the host or how the bacterium or virus enters the body but also how it establishes itself in the host organism. What is the receptor that allows a virus to enter the cell? Which cells does a bacterium first target or how does it evade an immune response? While other studies of bacteria like Yersina pestis have looked at imaging the bacterial burden in model mice, questions remain about how this bacterium gets from the skin after an infected flea bites to the draining lymph nodes, where the bacteria replicate and enter the bloodstream and infection becomes fatal. A recent PLOS Pathogens article examined how the nonmotile Y. pestis disseminated itself starting from a tiny innoculation mimicking a flea bite on a mouse ear and following pathogen interaction with the host from skin to lymph node. Continue reading “Tracking the Beginning of a Pathogenic Bacterial Infection”
When discussing human evolution, many people think of bones uncovered in Africa like the skeleton named Lucy or mention that Neanderthals and anatomically modern humans coexisted in Europe. However, our evolution has not ceased in recent years even if the evolutionary changes are not as physically obvious as the difference between Homo erectus and Homo sapiens’ skulls. Any changes in our environment influence the complement of genes we pass on to our children and grandchildren and even if those genes are passed on to the next generation. When it comes to diseases, some deadly infections can have a tremendous influence on the immune genes passed on to descendants, especially by those individuals that survived the disease and had children. However, determining whether any genetic changes are due to disease can be difficult. There is not always a control population for a particular disease where one group was infected and the other not, to identify changes. Luckily for the study published in PNAS, researchers had access to two populations that had experienced similar disease pressure (e.g., the Black Death) and one genetically related population that had not. Continue reading “The Role of the Black Death in Human Evolution”
By clicking “Accept All”, you consent to the use of ALL the cookies. However you may visit Cookie Settings to provide a controlled consent.
If you are located in the EEA, the United Kingdom, or Switzerland, you can change your settings at any time by clicking Manage Cookie Consent in the footer of our website.
Necessary cookies are absolutely essential for the website to function properly. These cookies ensure basic functionalities and security features of the website, anonymously.
This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Analytics".
The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional".
This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Other.
The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Advertisement".
This cookie is set by GDPR Cookie Consent plugin. The cookies is used to store the user consent for the cookies in the category "Necessary".
This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Performance".
6 months 2 days
This cookie is set by the provider Media.net. This cookie is used to check the status whether the user has accepted the cookie consent box. It also helps in not showing the cookie consent box upon re-entry to the website.
This cookie is used to store the language preferences of a user to serve up content in that stored language the next time user visit the website.
Analytical cookies are used to understand how visitors interact with the website. These cookies help provide information on metrics the number of visitors, bounce rate, traffic source, etc.
This cookie is associated with Sitecore content and personalization. This cookie is used to identify the repeat visit from a single user. Sitecore will send a persistent session cookie to the web client.
This domain of this cookie is owned by Vimeo. This cookie is used by vimeo to collect tracking information. It sets a unique ID to embed videos to the website.
1 month 18 hours 24 minutes
This cookie is used to calculate unique devices accessing the website.
This cookie is installed by Google Analytics. The cookie is used to calculate visitor, session, campaign data and keep track of site usage for the site's analytics report. The cookies store information anonymously and assign a randomly generated number to identify unique visitors.
This cookie is installed by Google Analytics. The cookie is used to store information of how visitors use a website and helps in creating an analytics report of how the website is doing. The data collected including the number visitors, the source where they have come from, and the pages visted in an anonymous form.
Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. These cookies track visitors across websites and collect information to provide customized ads.
1 year 24 days
Used by Google DoubleClick and stores information about how the user uses the website and any other advertisement before visiting the website. This is used to present users with ads that are relevant to them according to the user profile.
This cookie is set by doubleclick.net. The purpose of the cookie is to determine if the user's browser supports cookies.
5 months 27 days
This cookie is set by Youtube. Used to track the information of the embedded YouTube videos on a website.
Performance cookies are used to understand and analyze the key performance indexes of the website which helps in delivering a better user experience for the visitors.
This cookies is set by Youtube and is used to track the views of embedded videos.
This is a pattern type cookie set by Google Analytics, where the pattern element on the name contains the unique identity number of the account or website it relates to. It appears to be a variation of the _gat cookie which is used to limit the amount of data recorded by Google on high traffic volume websites.