But where did these viruses first come from?
Unlike bacteria, viruses aren’t living organisms — they can’t reproduce on their own. Instead, they hijack cells to multiply, spread and cause disease.
But what if it wasn’t always this way?
Scientists studying a so-called giant virus called a Tupanvirus (named for the South American Guarani God of Thunder) found that it, unlike the viruses we encounter today, had an almost complete machinery to take care of itself.
This recent discovery has refuelled the debate over the origin of viruses.
There is no physical fossil record of viruses like there is for the dinosaurs.
One way scientists detect viruses, and study their origins, is to look for their genetic material— molecules of DNA or RNA — in animal tissues and soil.
Even though the movies might have you believe otherwise, viral genetic material has never been detected in fossilized plant leaves or in insects trapped in amber.
However, some ancient viruses have been detected in permafrost in Siberia, and there are hopes of discovering more as global warming continues to thaw ground that has been frozen for thousands of years. Until then, we remain limited in our ability to precisely reconstruct the origin of viruses.