Revived 'Zombie Viruses' from Permafrost Pose Modern Threat.

Scientists have discovered that "zombie viruses" found in permafrost, some of which are tens of thousands of years old, can infect amoeba cells once revived. The viruses were found in seven permafrost samples from ancient Siberia and were in a dormant state for between 27,000 and 48,500 years. As permafrost melts due to climate change, viruses capable of infecting humans may emerge, and the release of organic matter frozen for up to a million years could further enhance the greenhouse gas effect.