Given the task definition and input, reply with output. In this task, you are given a text of many news articles seperated by special token "|||||". Your task is to summarize them.

(A) DNA damage patterns for RISE505 and RISE509. The frequencies of all possible mismatches observed between the Y. pestis CO92 chromosome and the reads are reported in gray as a function of distance from 5′ (left panel, first 25 nucleotides sequenced) and distance to 3′ (right panel, last 25 nucleotides). The typical DNA damage mutations C>T (5′) and G>A (3′) are reported in red and blue, respectively. 
  
 (B) Ancient DNA damage patterns (n = 7) of the reads aligned to the CO92 chromosome and the Y. pestis associated plasmids pMT1, pCD1 and pPCP1. The boxplots show the distribution of C-T damage in the 5′ of the reads. The lower and upper hinges of the boxes correspond to the 25th and 75th percentiles, the whiskers represent the 1.5 inter-quartile range (IQR) extending from the hinges, and the dots represent outliers from these. 
  
 (C) DNA fragment length distributions from RISE505 and RISE509 samples representing both the Y. pestis DNA and the DNA of the human host. The declining part of the distributions is fitted to an exponential model (red). 
  
 (D) Linear correlation (red) between the decay constant in the DNA of the human host and the associated Y. pestis DNA extracted from the same individual (R2 = 0.55, p = 0.055). The decay constant (λ) describes the damage fraction (i.e., the fraction of broken bonds on the DNA strand). 
  
 (E) Distribution of edit distance of high quality reads from RISE505 and RISE509 samples mapped to either Y. pestis (dark gray) or Y. pseudotuberculosis (light gray) reference genomes. The reads have a higher affinity to Y. pestis than to Y. pseudotuberculosis. ||||| Mikhail V. Khalyapin 
  
 The Black Death notoriously swept through Europe in 1347, killing an estimated 50 million people. Yet DNA from Bronze Age human skeletons now shows that the plague had first emerged at least as early as 3,000 bc. The earlier outbreak probably did not spread as ferociously, the analysis reveals — but it may nonetheless have driven mass migrations across Europe and Asia1. 
  
 The bacterium Yersinia pestis is suspected to have caused the Black Death and other ancient plagues. Historical descriptions of the disease’s quick spread and symptoms such as pus-filled growths match modern outbreaks of bubonic plague caused by the bacterium, and the remains of ancient plague victims have been found to contain Y. pestis DNA2, 3. 
  
 The earliest of these infections comes from a burial in Germany linked to the six-century Plague of Justinian3. Yet some historians suspect that Y. pestis was also responsible for earlier outbreaks such as the Plague of Athens, which struck the city-state in the fifth century bc, at the height of the Peloponnesian War. 
  
 The Bronze Age — between about 3000 and 1000 bc — was a tumultuous period that saw new cultural practices and weapon and transport technologies spread rapidly across Eurasia. Earlier this year, a pair of ancient-genome studies documented a massive exodus of people from the steppe of what is now Russia and Ukraine; they scattered west into Europe and east into central Asia4, 5. 
  
 “But we didn’t know what the cause of these quite sudden migrations was,” says Morten Allentoft, an evolutionary geneticist at the Natural History Museum of Denmark in Copenhagen, who was part of a team that sequenced DNA from 101 Bronze Age skeletons4. 
  
 Suspecting that an infection similar to plague might have been involved, the same team analysed 89 billion fragments of raw DNA data from the Bronze Age skeletons in search of Y. pestis sequences. Teeth from 7 of the 101 individuals tested positive, and 2 contained enough plague DNA to generate complete genome sequences. The oldest of the Bronze Age plague strains came from an individual who lived nearly 5,000 years ago in southeast Russia, pushing back the origins of plague by some 3,000 years. The findings are published today in Cell1. 
  
 Plague without fleas 
  
 The Bronze Age plague strains were very similar to the bacteria responsible for the Black Death and modern outbreaks. They shared nearly all of the ‘virulence genes’ that distinguish Y. pestis from a related, although much less deadly, bacterium that infects the intestines. 
  
 But the analysis revealed that plague might have been less transmissible in the early Bronze Age. The six oldest Bronze Age strains lacked a gene called ymt that helps Y. pestis to colonize the guts of fleas, which serve as an important intermediary. In outbreaks of bubonic plague, infected fleas (often travelling on rodents) transmit the bacteria to humans living nearby. Without fleas as a go-between, Y. pestis spreads much less efficiently through blood (where it is known as septicaemic plague) or saliva droplets (pneumonic plague). An early Iron Age skeleton from Armenia dated to around 1000 bc was infected with Y. pestis that harboured ymt as well as another mutation linked to flea-aided transmission. 
  
 Wyndham Lathem, a microbiologist at Northwestern University’s Feinberg School of Medicine in Chicago, Illinois, says that in the absence of ymt, Bronze Age plague victims would have probably contracted pneumonic plague, as opposed to the bubonic form. All the Bronze Age strains also contained another virulence gene, pla, which Lathem's team has shown is important in infecting the lung6. 
  
 Plague may have been less transmissible without fleas, but it would have been no less deadly. More than 90% of untreated cases of pneumonic plague are fatal. 
  
 Such outbreaks could have aided the spread of Eastern European steppe herders known as the Yamnaya during the Bronze Age, says Johannes Krause, an evolutionary geneticist at the Max Planck Institute for the Science of Human History in Jena, Germany. The Yamnaya rapidly supplanted local farming populations in Western Europe between 3000 and 2500 bc. “How is it possible that the local farmers have been replaced by people from the steppe? A pandemic is a good possibility,” Krause says. |||||

The plague is apparently a lot older than we thought. Scientists says the disease was responsible for a massive migration of people across Europe and Asia during the Bronze Age—approximately 3,000 years earlier than it was believed to have existed, according to a study published Thursday in Cell. Nature reports that scientists discovered a mass exodus from what is now Russia and the Ukraine between 3,000 and 5,000 years ago and were looking for what caused it. To that end, they studied 89 billion DNA fragments from 101 Bronze Age skeletons. “Plague was just a long shot,” researcher Dr. Eske Willerslev tells the New York Times. DNA from the plague-causing Yersinia pestis bacteria was found in the teeth of seven of the Bronze Age skeletons, the oldest having lived nearly 5,000 years ago in what is now Russia, according to Nature. “To my mind, this leaves little doubt that [the plague] has played a major role in those population replacements,” Willerslev tells the Times. According to Nature, the Bronze Age plague strain is similar to the infamous Black Death and modern bubonic plague, though it probably didn't spread as easily. That's because researchers found it lacked the gene allowing it to live inside fleas, which are helpful when transporting the disease between rodents and humans. The ancient plague was still fatal in 90% of cases, and the Times reports humans may have helped it along by hunting infected rodents for food. (This year, the US saw a first-of-its-kind case involving an infectious dog.)