Scientific humour can often be obtuse to lay people, but sometimes it can also be trouble for scientists.
Such was the case last week when an amazing new discovery was almost overshadowed by an offhand quip by one of the one of the researchers who made the discovery.
Pandoravirus is a brand new class of virus that is remarkably huge. At one micron in diameter it is 10 times the size of most other viruses.
Its genome is also comparatively massive. Typical viruses have around 10 genes, while this one has more than 2,500.
Even more astounding than its prodigious size, however, is the fact that only six per cent of its genes are similar to anything scientists have ever seen.
This prompted Jean-Michel Claverie, one of the lead researchers to say, in jest, that it might as well have come from Mars.
Unfortunately, many media outlets did not get the joke and reported that scientists believe the virus may have actually come from the red planet.
Claverie regrets saying it.
The other unfortunate thing about the reporting of the discovery in the mainstream media was that it led to suggestions that the virus' existence challenges standard evolutionary models.
The reason for this erroneous idea is that Pandoravirus does not neatly fit into any of the three recognized domains of life, eukarya, bacteria and archaea.
The domains are simply a classification system. As new discoveries are made, classification schemes change, but that doesn't mean the fundamental tenets of evolutionary biology are invalid.
The original classification system divided life into two kingdoms, plants and animals. As scientists realized life was far more complex than that, they had to come up with a more robust system.
In the 18th century, Carolus Linnaeus developed a heirarchical system for grouping organisms based on taxonomy. Most people have at least some familiarity with this system from high school biology: Kingdom, Phylum, Class, Order, Family, Genus and Species.
With the discovery of DNA and RNA and the development of genetic sequencing, however, scientists had a new tool for analyzing the relationships between organisms.
In the early 1960s, it was generally accepted that there were two super Kingdoms (later to be called domains), prokaryotes and eukaryotes based on cellular organization, prokaryotes being those organisms whose cell or cells lacked a nucleus. Basically the "tree of life" was divided into bacteria and everything else.
In 1977, Carl Woese revolutionized microbiology with the discovery of archaebacteria (archaea). Before Woese, the organisms in this domain were largely thought to be extreme versions of bacteria that evolved from other organisms we are familiar with. Now, it is almost universally accepted that the archaea are ancient forms that have very close evolutionary connections to the very earliest organisms on Earth.
Some people have suggested that Pandoravirus is so different from anything in the other three domains that it is deserving of its own domain.
Others, including Claverie and co-discoverer Chantal Abergel, scoff at the idea.
I think it's a little premature. Undoubtedly, this is just the beginning and it is very exciting that life on Earth has just become much more complex again at a time when many people thought there just wasn't that much left to discover.
Furthermore, there is no end of research into its evolutionary and ecological implications.
As for classifying it, the time will come that we will figure out what we're going to do with it, remembering that classification systems are simply tools to help us make sense of the world. When a tool doesn't work any more, we build a better one.
