This is an EXAMPLE of "micro-evolution". The bacteria is still bacteria. Some people try to use micro-evolution to confuse with "macro-evolution", like from a whale to a human.
Micro-evolution is how we get different shapes, sizes & colors. And sometimes (as in this case) bad things can happen.
The germ that caused the “Black Death” is only a young bug, “evolutionarily speaking,” say scientists at Northwestern. Although it had the ability to cause a severe respiratory illness early on, two mutations occurred that gave it the ability to spread rapidly through the air, leading to the pandemics that killed millions in Europe.
According to the researchers. Y. pestis evolved from a similar bacterium, Y. pseudotuberculosis, that is still around today and causes mild gut infections. The first mutation from the oldest-known ancestral strain gave it the ability to infect the lungs and cause pneumonic plague, a disease spread by rodents carrying fleas.
A second mutation—a single amino acid change—gave Y. pestis 100 times the ability to affect deep tissues and lymph nodes. This is the fast-killing strain that caused bubonic plague. Since the
first known pandemic was in the time of Justinian (6th century), the deadly combo must have occurred around that time. In all, the changes to Y. pestis from its ancestral form must have occurred within the last 10,000 years—making it extremely young, considering that bacteria are among the earliest life forms in the evolutionary timeline.
Comparing the earliest known strain of Y. pestis to the pneumonic plague version, “The ancestral strains lacked the gene for a certain protein, called PLA protease.” (*) Adding that one gene can turn the harmless strain into a strain that causes pneumonic plague. Other genetic differences between the two strains appear irrelevant to disease potential. The articles do not say if the germ acquired the gene through horizontal gene transfer.
One further mutation changed a single amino acid. That was sufficient to cause bubonic plague, they say. “Before the amino acid mutation, the bacteria would have had a much more difficult time moving into a person’s bloodstream and causing a body-wide infection, the researchers said.”
The Black Death of the 14th century was undoubtedly exacerbated by ignorance of the agent and poor sanitary practices. Bacteria were only detected in the 17th century by Leeuwenhoek. Even so, cleanliness, careful observation and clear thinking might have limited the spread of the disease. Medieval towns were filthy places, overrun by rats that carried the fleas carrying the germ. Y. pestis is still endemic in the United States, the researchers note, but there are only about 7 cases a year, primarily in the southwestern US.
It appears that the deadly pathogen emerged by mistake. “The emergence of new pathogenic clones has been directly linked with both the gain and loss of genetic elements by bacteria that were previously thought to be non-virulent,” the authors say in Nature Communications. If the PLA protease gene was acquired by horizontal gene transfer, no new genetic information was involved. The mutations, moreover, occurred in historic times.
*A protease is an enzyme that acts on a protein; in this case, it lyses (disrupts) plasminogen activator (PLA). Hundreds of proteases are known. They operate in every kind of life. Some human proteases are involved in digestion. Other enzymes, protease inhibitors, regulate their action." CEH
"The Plague of Justinian (541–542) was a pandemic that afflicted the Eastern Roman Empire (Byzantine Empire), especially its capital Constantinople, the Sassanid Empire, and port cities around the entire Mediterranean Sea." wikipedia
Micro-evolution is how we get different shapes, sizes & colors. And sometimes (as in this case) bad things can happen.
For we know that the whole creation groaneth and travaileth in pain together until now.
Romans 8:22
"The Black Plague of the Middle Ages happened by accident. It was enabled by two mutations to a bacterium, scientists claim.The germ that caused the “Black Death” is only a young bug, “evolutionarily speaking,” say scientists at Northwestern. Although it had the ability to cause a severe respiratory illness early on, two mutations occurred that gave it the ability to spread rapidly through the air, leading to the pandemics that killed millions in Europe.
While studying Yersinia pestis, the bacteria responsible for epidemics of plague such as the Black Death, Wyndham Lathem, Ph.D., assistant professor in microbiology-immunology at Northwestern University Feinberg School of Medicine, found a single small genetic change that fundamentally influenced the evolution of the deadly pathogen, and thus the course of human history.
...demonstrated how the acquisition of a single gene caused the shift of Y. pestis from causing a primarily gastrointestinal infection to a more serious and often fatal respiratory disease. They further showed how later modifications of this gene enhanced infections associated with the bubonic plague.
According to the researchers. Y. pestis evolved from a similar bacterium, Y. pseudotuberculosis, that is still around today and causes mild gut infections. The first mutation from the oldest-known ancestral strain gave it the ability to infect the lungs and cause pneumonic plague, a disease spread by rodents carrying fleas.
A second mutation—a single amino acid change—gave Y. pestis 100 times the ability to affect deep tissues and lymph nodes. This is the fast-killing strain that caused bubonic plague. Since the
Comparing the earliest known strain of Y. pestis to the pneumonic plague version, “The ancestral strains lacked the gene for a certain protein, called PLA protease.” (*) Adding that one gene can turn the harmless strain into a strain that causes pneumonic plague. Other genetic differences between the two strains appear irrelevant to disease potential. The articles do not say if the germ acquired the gene through horizontal gene transfer.
One further mutation changed a single amino acid. That was sufficient to cause bubonic plague, they say. “Before the amino acid mutation, the bacteria would have had a much more difficult time moving into a person’s bloodstream and causing a body-wide infection, the researchers said.”
The Black Death of the 14th century was undoubtedly exacerbated by ignorance of the agent and poor sanitary practices. Bacteria were only detected in the 17th century by Leeuwenhoek. Even so, cleanliness, careful observation and clear thinking might have limited the spread of the disease. Medieval towns were filthy places, overrun by rats that carried the fleas carrying the germ. Y. pestis is still endemic in the United States, the researchers note, but there are only about 7 cases a year, primarily in the southwestern US.
It appears that the deadly pathogen emerged by mistake. “The emergence of new pathogenic clones has been directly linked with both the gain and loss of genetic elements by bacteria that were previously thought to be non-virulent,” the authors say in Nature Communications. If the PLA protease gene was acquired by horizontal gene transfer, no new genetic information was involved. The mutations, moreover, occurred in historic times.
*A protease is an enzyme that acts on a protein; in this case, it lyses (disrupts) plasminogen activator (PLA). Hundreds of proteases are known. They operate in every kind of life. Some human proteases are involved in digestion. Other enzymes, protease inhibitors, regulate their action." CEH
"The Plague of Justinian (541–542) was a pandemic that afflicted the Eastern Roman Empire (Byzantine Empire), especially its capital Constantinople, the Sassanid Empire, and port cities around the entire Mediterranean Sea." wikipedia