There are a lot of old things in the world: Tortoises that have been around for centuries, trees that have seen some nine thousand years, and even a few mad-made structures that have witnessed the passing of almost six millennia. However, few things compare to Pithovirus sibericum, a 30,000 year old virus that was recently revived by scientists.
There are a number of hidden treasures stored away in Earth's permafrost. These gems from prehistoric times give us important clues about the development of modern organisms and the versatility of life. "Permafrost" is soil that is permanently frozen, as such, it is a great record keeper—preserving ancient matter for centuries on end (technically, "permafrost" is any soil that has been frozen for at least two years; however, much of our planet's permafrost has been at subzero temperatures for tens of thousands of years). To see an example of the treasures locked away in this ice, we've to look back no further than 2012, when scientists discovered that 30,000 year old fruits that had (apparently) been buried by squirrels could be brought back to life and grow new flowering plants. This discovery inspired evolutionary biologists Jean-Michel Claverie and Chantal Abergel to see if other living things could be brought back from the icy hands of death (pun intended). Specifically, Claverie and Abergel wanted to know if microbes could survive in the frozen wastes below Earth's surface.
As it turns out, they can.
In order to search for ancient microbes, the researchers obtained samples of thawed permafrost taken from 100 feet below the cold, far northeast of Russia. They used amoebae as a kind of bait. They hoped that, if any viruses were in the samples, they would awaken and attack the amoebae. They were not disappointed. When the amoebae started dying, the scientists checked their samples and found the Pithovirus inside. And it is still infectious.
Fortunately for us, the virus is very simple and only attacks single-celled amoebae; however, this discovery raises a lot of questions about what the recent global warming trend will mean long term.
“The revival of such an ancestral amoeba-infecting virus … suggests that the thawing of permafrost either from global warming or industrial exploitation of circumpolar regions might not be exempt from future threats to human or animal health,” scientists wrote in the Proceedings of the National Academy of Sciences.
Similarly, Clevarie told the BBC that this may discovery may lead to some harsh truths related to modern microbes:
"If it is true that these viruses survive in the same way those amoeba viruses survive, then smallpox is not eradicated from the planet — only the surface. By going deeper we may reactivate the possibility that smallpox could become again a disease of humans in modern times."
Of course, new and deadly viruses or horrifying bacteria could spring up anywhere, and our own obsessive use of antibiotics is already speeding us down the path to a host of terrifying new superbugs. So the point of mentioning the link between global warming and ancient viruses is not to bring terror or to assert that some thawed virus will wreak havoc on modern humanity. Rather, the purpose is to note the complex cause and effect relationship that exists between all things on Earth.
Ultimately, Pithovirus is the oldest virus that has ever been awoken after such a long state in dormancy and still been infectious. It is also enormous (relatively speaking). It measures 1.5 micrometers long, which is about the size of a bacterium. This makes the virus the largest in a class of giant viruses that were uncovered about a decade ago. These viruses are about 100 times larger than typical viruses. For comparison, if an average virus were the size of a baseball then bacteria would be the size of the pitchers mound and a human cell would be the size of a baseball stadium.