Earliest evidence of humans catching disease from animals dates to 6,500 years ago
Diseases began to jump from animals to humans at least 6,500 years ago, found researchers in a new study of old DNA.
After analyzing the ancient DNA of 1,313 prehistoric humans of Europe and Asia, the researchers have drawn a card and a chronology of human infectious diseases which extend over 37,000 years. Within this long history, they discovered the oldest evidence of zoonotic disease – in which pathogens in animals are transferred to humans – dated 6,500 years ago.
The researchers described their results in a study published Wednesday July 9 in the journal NatureNoting that cases of zoonotic disease probably occurred before this point. But they said that the risk and the extent of the transmission of these diseases have probably increased as humans interacted more frequently with animals, namely by agriculture and farming.
Migration has probably also played a role, as individuals may have worn zoonotic diseases to new populations that had not yet been exposed to them.
“Today, zoonoses represent more than 60% of newly emerging infectious diseases,” wrote the researchers.
The researchers found a peak in proof of zoonosis in samples aged about 5,000 years. They argue that this coincides with the period when the domestication of cattle has become more widespread. (The evidence suggests the domestication of animals started around 8,000 to 10,000 years And then probably took time to spread to various geographies.)
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Until now, questions have remained in the place and when known human pathogens have first emerged and how they were distributed in the world. Thanks to new technologies that can capture genomic evidence of these diseases in ancient DNA, some of these questions are starting to answer.
In total, 214 known human pathogens were detected in the study’s DNA samples, which were collected on the bones and teeth of ancient human remains. The oldest case with a known pathogen discovered in the study concerned Corynebacterium DiphheriaeThe bacteria behind diphtheria. The DNA of the microbe was discovered in a sample of the Mesolithic period and dated 11,400 years.
Twelve cases involved the Yersinia enterocolitica bacteria behind zoonotic disease yersiniosiswhich causes various symptoms, including fever and diarrhea. The oldest remains showing evidence of this pathogen were found in Denmark and are around 6,500 years old.
Researchers also found evidence of certain better known pathogens – including 42 suspicious cases of bacteria causing the plague Yersinia Pestis – In about 3% of their samples. However, they did not detect the pathogen responsible for tuberculosis:: Mycobacterium tuberculosis.
The team suspects that they have not detected Mr. Tuberculosis Because it is generally a low -loading blood infection. Due to the data set they used, they were most likely to detect bugs that accumulate in high concentrations in the blood during an infection.
The samples of human remains consisted of a mixture of human, germ and other DNA. After having excluded any human DNA, the team then identified which DNA belonged to human pathogens and which came from other sources, such as bacteria involved in the decomposition processthe soil or human microbiome.
Study limitation is that the technology used does not detect RNAA DNA cousin that is the basis of many germs. Flu viruses contain RNA, for example, RNA analysis could have provided evidence of different influenza pandemics through history.
“There are many epidemic type pathogens that are RNA viruses that we would like to study from the past. But the problem with them is that RNA is not a molecule as stable as DNA”, the main author of the study Martin SikoraAn associate professor who studies human and pathogenic evolution at the University of Copenhagen, told Live Science. “So far, we have not really managed to extract this type of information from archaeological remains.”
This is “the biggest study to date on the history of infectious diseases,” said researchers in a statementAdding that it could potentially have implications for the future of medicine, including the development of vaccines.
Sikora said that by reconstructing the genomes of these former pathogens, they sometimes have enough data to recover the whole sequence of the genome of a particular germ. In theory, new vaccines could be developed on the basis of this information and would be available to protect humans from viruses that are not there now but could emerge in the future, he suggested.
