One of the reasons that DNA is typically easier to recover from ancient samples is that it is usually found as 2 strands twisted together making it more stable. Parvovirus B19 (B19V) has a genome that is a single strand instead of a double, meaning it typically would not last as long in remains. These authors recovered B19V DNA from remains that were between 0.5 and 6.9 thousand years old and demonstrated the virus has been associated with humans for thousands of years.

DNA from variola virus which causes smallpox has been recovered from a 300 year old Siberian mummy and a Lithuanian mummy from the 1600's.

DNA from hepatitis B virus has been recovered from skeletons found in Germany, a 16th century child mummy in Italy, and skeletons scanning a period of nearly 4,000 years from a variety of regions.

The average speed that a genome accumulates changes to the nucleotide sequence also known as mutations.

DNA and RNA are molecules that provide the code for cells to carry out their functions. They are composed of a small number nucleotides and the order of these nucleotides determines function. Sequencing allows us to determine what the order of nucleotides within a DNA or RNA molecule.

The full set of genes or heritable genetic material like DNA or RNA present in an organism.

When humans transitioned from small migrating groups of hunter gatherers to more stationary settlements that focused on farming and raising animals. This led to a significant growth in population sizes.

Some environments are more likely to preserve genetic material than others. The oldest DNA samples have been recovered from permafrost or regions where the ground remains permanently frozen. Other favorable environments include high salt concentrations, very dry environments like deserts, or environments with very low oxygen like bogs a type of wetland that contains large amounts of dead plant material.

Given the results demonstrated by Smith and colleagues, the authors decided to look at the size distributions and damage profiled of the RNA recovered from the lung tissue. They found fragments of much greater lengths than 30 nucleotides with fragments ranging from 217-233 nucleotides. They also found no evidence of RNA damage indicating formalin-fixed specimens could serve as a source of well preserved RNA molecules.

Authors generated RNA data from wolf skins and liver tissue of an ancient wolf relative. This is the oldest RNA ever sequenced and the RNA was also tissue specific. This work demonstrates that RNA could possibly be recovered from tissues preserved over thousands of years.

In the supplement, the authors use previous studies to assert that while not formally established, the transmission of RPV spilling over into humans is much more likely than the opposite occurrence. They support this with 4 points.

1. Cattle and other hoofed animal populations were likely large enough to support RPV before human populations were large enough to support measles.
2. Older descriptions of RPV seem to exist than descriptions of measles.
3. Other viruses related to measles infect cattle, so it is more likely that RPV infected humans and became measles once rather than measles becoming a cattle virus several times.
4. Other Paramyxoviruses originated in domesticated animals and jumped to humans. Even with this evidence it cannot be ruled out that transmission from humans to cattle occurred.

Wertheim and Pond demonstrate the purifying selection or the removal of damaging alleles can make pathogens seem younger than they really are. Using models that take this phenomenon into account, they provide evidence that the origin of measles is older than previous estimates showed.

The point where rinderpest and measles virus became different species. Virus species are distinguished by a variety of criteria including structural factors, host range, the disease they cause, and genetic similarities.

Because we do not have sequence data on all outbreaks occurring after measles emerged as a human virus, we cannot say if all outbreaks of similar diseases were caused by measles or a similar related virus that then died out.

This book describes the history of outbreaks of disease from cattle in humans from the Roman empire to the 20th century.

Measles is only able to infect humans, while rinderpest virus is only able to infect cattle. This article provides evidence that outbreaks that occurred during the medieval period were a separate but related virus that was able to infect both cattle and people.

When human populations were large enough, this virus mutated again and kept spreading throughout human populations. This virus eventually became modern-day measles.

Bovine virus mutates quickly because it is an RNA virus. It may have mutated so that it was able to infect humans on multiple occasions. However, human populations were not yet at the critical community size, so the virus died out.

Before measles became a disease of humans, its predecessor, bovine virus, was common in cattle and possibly other hoofed mammals. This bovine virus was already distinct from peste des petits ruminants virus which is the virus most closely related to it.

This study assessed regions where major settlements increased in size (upswept) or declined significantly and stayed down without rebounding (downswept). They identified 18 total significant upsweeps including those around 300 BCE.

This book provides information on measles expansion, consolidation, and retreat pre and post vaccine introduction within different geographical regions. They present mathematical models to describe the spread of measles epidemics and forecast geographical spread in various conditions.

When the identification of an illness is carried out after a patients death.

A Greek physician and surgeon who influenced the development of several medical disciplines.

A collection of medical texts from ancient Greece that are attributed to various physicians from the Alexandrian era (4th century BC).

Nonsynonymous mutations change the sequence of a protein and are more likely to cause changes in function, while synonymous mutations don't change the protein and are silent in terms of function.

Critical community size (CCS) is the smallest population size that can support the continued persistence of a human-to-human pathogen that is unable to infect animals. Bartlett estimated the critical community size to be around 250,000 using data from Manchester records. Black then used case reports from 19 island communities to establish a CCS of 500,000. Finally, Keeling and Greenfell used prevaccination data from England and Wales and estimated a CCS between 250,000 and 400,000.

Rhazes was a notable physician who authored more than 200 books and treatises or formal works on subjects like medicine and philosophy. His document "A Treatise on Smallpox and Measles" was the first book to distinguish between the two diseases.

A virus that causes fever, ulcers of the mouth, pneumonia, stomach problems, and sometimes death in goats and sheep.

When vaccines for measles were introduced the number of people infected declined significantly this caused many strains to die out.

A family of viruses that infect vertebrates or animals with a spine. They cause a variety of diseases including measles, mumps, and various respiratory tract infections.

https://www.aaas.org/rudolph-virchow-father-cellular-pathology

Pneumonia is a type of infection causes by a variety of organisms that inflames the lungs. Bronchopneumonia is a type of pneumonia that causes inflammation of a part of the lungs called the alveoli. This inflammation makes it difficult for the lungs to get enough air.

These authors took the collection of overlapping DNA fragments produced through sequencing and lined them up to a genome of measles that had already been constructed.

RNA degrades more rapidly in the environment because it exists as a single strand while DNA is typically found in a double stranded structure. RNA is also made from ribose while DNA is made with deoxyribose which are two different sugars. The difference in the structure of these sugars makes RNA more susceptible to breaking down when it encounters water.

Muhlemann and colleges isolated DNA from ancient human parvovirus 19 and hepatitis B viruses to obtain genomes sequences. These sequences were then used to assess the historical relationship between these viruses and the human population and learn more about viral evolution.

This occurs when a nucleotide is switched at the same spot in a gene sequence multiple times. It makes it seem like the rate of sequence divergence is lower than what it actually is.

Selection refers to natural selection the process by which organisms that are better adapted for their environment survive and produce more offspring. Natural selection causes the evolution of species. Purifying selection removes harmful variations from the population by ensuring those individuals produce fewer offspring.

These studies look at how evolutionary rates change over time and how these alterations can be accounted for in models. Ho and colleagues assert that rates of evolution change over time as a result of a variety of factors and refute the claims of Emerson and Hickerson. Aiewsakun and Katzourakis demonstrated that the time dependence in rate estimates applies for viruses. Accounting for rate variation in can provide more biologically realistic models.

Chronous refers to time while hetero means different meaning that the measles genomes analyzed were from different timepoints.

Wolfe and colleagues assessed the origin of significant human infectious diseases. They found the origins of diseases varied based on climate and identified stages of a disease transitioning from an animal pathogen to a human pathogen. They found that diseases like measles from mild climates frequently originated from domestic animals like cattle.

Measles is easily confused with smallpox because they both cause rash and fever. Distinguishing smallpox and measles is no longer a problem since smallpox has been eradicated.

While fixing with formalin preserves biological samples, it causes cross-linking or the chemical joining of molecules. These chemical bonds interfere with the sequencing process. Treating the tissue with heat before purifying the genetic material helps to fix this problem.

The speed at which mutations occur to a genome.

Refers to a branch of statistics based on Bayes' theorem. This theorem is used to update the probability or likelihood of a hypothesis or proposed explanation as more information is available. This method allows for inference or the ability to draw conclusions about a larger group based on a smaller sample.

A disease is endemic when it is found regularly in a population.

https://www.cidrap.umn.edu/news-perspective/2011/05/oie-declares-rinderpest-eradicated

https://www.nytimes.com/2019/11/26/health/measles-outbreak-epidemic.html

A vaccine is a substance that causes the body to recognize and stop a disease-causing agent via a type of protein called antibodies. Antibodies combine with proteins on the surface of invading pathogens and alert the immune system. A live-attenuated vaccine uses a weakened for of a virus to cause this immune response.