On Earth for millions of years: Viruses

Something was wrong with those bones, Yara Haridy was sure. The caudal vertebrae of the lizard-like animal that lived in the Permian – 289 million years ago! – were fused together in an unusual way.

The paleontologist from Berlin’s natural history museum felt over the seam. Had a disease caused the two vertebrae to fuse? And could this possibly be detected inside the bone? She decided to pursue her curiosity – and found clues about the oldest viruses in the world!

In 2019, together with colleagues from Museum für Naturkunde Berlin, Charité Berlin and University of Toronto, she published her results: The animal suffered from a bone condition similar to Paget’s disease, identified in an isolated pair of tail vertebrae discovered in an Early Permian cave at Richards Spur, Oklahoma.

Micro-CT scanning at the Museum für Naturkunde allowed to examine both the external and internal structure of the elements, revealing that in some places the bone had been thinned by high levels of reabsorption, while in other areas excessive bone growth had resulted in abnormal bone thickening and the ultimate fusion of the two vertebrae.

Charles Darwin once said that under today's conditions one can no longer understand the beginning of life. The current state of research is: the Earth was formed 4.5 billion years ago and the first biomolecule 3.8 billion years ago. Scientists still disagree on how these riboenzymes came about. Some believe life came from outer space. These molecules had the ability to duplicate and multiply by adding new molecules, they made copies of themselves. Sometimes that didn't work properly, there were mutations.

The first viruses arose before all life. Over time, they adapted to new hosts. The oldest evidence of bacteria is found, for example, in so-called stromatolites, the oldest of which are 3.6 billion years old and were found in Australia. A direct proof of ancient viruses, however, is still not known.

Another object of research, for instance, was Tristan Otto, the famous Tyrannosaurus rex. Scientists examined peculiar swellings at its jaw bones – possibly originating from an infection.

In this way, scientists continue finding clues to how viruses may have affected life on Earth. One could say that what happened during the Cold War – a mutual arms race – has been practiced by them for millions of years. It cannot be the intention of a virus to kill the host because that would mean its end.

Therefore, in the course of evolutionary interrelationships, there are mutual adjustments, further developments and adjustments again. Sometimes a large number and variety of hosts are available, as is the case with rabies, which can affect many warm-blooded animals. Sometimes the host would become more resilient or the virus not as aggressive – the cold virus, for example.

Researchers have been able to prove that viruses have enormously accelerated evolution. Some even see viruses as the engine of evolution, in which viruses have contributed to the exchange of genetic material from the beginning hundreds of millions of years ago.