The History of Earth: VIRUS

Viruses are all around us, yet we don’t know the answer to the most basic question about them. Welcome to Part 22 of the History of Earth.

Without Bernie, © the Author

Is a virus alive?

Amazingly, no-one really knows.

This is largely because, as we discovered in Part 21, ‘alive’ is a nebulous concept.

But, if there is a line between life and non-life, viruses straddle it.

Let’s start by asking: what is a virus?

Wikipedia defines it as, “a submicroscopic infectious agent that replicates only inside the living cells of an organism”.

Let’s break that down.

• Submicroscopic: They are submicroscopic; indeed, they are nothing more than a scrap of DNA or RNA wrapped in a protective coat. For the most part, they are far simpler than even bacteria. Many viruses have fewer than ten genes, whereas the simplest bacterium has 500.
• Infectious agents: They are infectious agents that invade other living organisms, including bacteria, archaea, fungi, plants, animals, and, of course, us. So, everything really.
• Replicate inside living cell: They replicate only inside the living cells of an organism: a virus hijacks a cell and…