Scientists have revived 13 ancient viruses, which are believed to be thousands of years old, from the frozen ground called permafrost in Siberia. The oldest virus called Pandoravirus yedoma is 48,500 years old and has broken the record of a 30,000-year-old virus that was found in 2013. The youngest virus found was 27,000 years old. Global warming has resulted in the thawing of permafrost and this has led to the emergence of these ‘zombie’ viruses. According to scientists, it is unlikely that the viruses will be a threat to humans.