THE VIRUS as Evolution’s Engine: Who’s Really Driving Your Car?

Baby, you can drive my car...

© 2009 Craig Chereek, all rights reserved

The best I can figure it, multi-celled organisms resulted from the exposure of primitive single-celled organisms to primitive viruses; the virus providing the pressure on the cell to adapt, with ultraviolet radiation providing the energy, flavored with occasional lengthy infusions of hot volcanic acids to season the broth.

Primarily because it’s so hard to find the fossil of something so small in a rock, and practicably because we probably wouldn’t recognize a fossil virus if we saw one (certainly not in the field) , nobody has a convincing scenario for the first appearance of the virus on earth, and even some at NASA are said to take seriously the idea of an extra-terrestrial source, perhaps, like the seas themselves, by cometary transport. (yes, it’s that prickly origin question, again. Any other ideas? We got nuthin’).

A curious-looking piece of rock that turns out to be a 1.2 billion year-old relic of Mendenhall gneiss is exposed in a road cut on either side of Upper Tujunga Road (just below it’s intersection with Angeles Crest Highway, shouting-distance) north of Los Angeles. I encourage anyone to see if you can find a fossil virus there. A smart geologist would say, ah, but that’s just cooled plutonic material, pressed, twisted and uplifted. You can’t expect to find the oldest fossil virus in sterile stone just because it’s old and handy, you have to ask, where was the virus thriving when it was young?

The answer is, you’ll need to find it in another fossil, a place it could make a living, so to speak. Maybe you’d have better luck looking in some two-billion-year-old fossil algae colonies called stromatalites- see http://www.fossilmuseum.net/Tree_of_Life/Stromatolites.htm, found in the Sharks Bay, Australia and the Gunflint Chert in Canada (and elsewhere). It’s where I’d look. I would also look in old salt mines, maybe in the black streaks in freshly-exposed cuts in the mile deep salt deposits under Detroit, Michigan, and in the Triassic rock salt mines of Winsford in Cheshire, England, for example. Those streaks have been identified as living bacterial colonies dating back to before the seas that bore them evaporated.

If I was looking for the oldest living primitive viruses- archaic, yet still-viable bacteria have also been identified in deposits deep in the Boulby potash mine in Cleveland, England, laid down during the Permian (225-270 MYA). Perhaps they carry archaic viruses. See http://mic.sgmjournals.org/cgi/reprint/139/5/1077.pdf

(I’d also like to hear a mechanism, whereby such a soft tissue could recognizably fossilize at all.  Let me know how it goes.)

A complete virus is 5 to 15% of the size of a typical cell , but the whole virus does not enter the cell. After affixing itself to the cell wall, the envelope stays behind, and only the genetic material of the virus enters.  This material is many orders of magnitude smaller than a bacteria, and pass easily through cell walls into the cell’s nucleus, which it attempts to co-opt  into virus factories by inserting their own DNA sequences into the host’s own reproductive sequences. Sometimes they are successful. Compared to a bacteria, however, a virus is infinitesimal. It is a very nimble aggregations of partly entwined proteins,  containing little more than instructions on how to refold themselves, depending upon what is encountered. Being single-stranded, these instructions are not redundant, and as such, are subject to extremely rapid mutations should conditions change; and they are much quicker to adapt than bacteria.

Logically, whatever was the very first adaptive response on the part of the first-attacked bacteria, it began a sequence which drifted toward the synthesis of an antibody. But as we know, a virus can dodge (mutate) faster than bacteria can aim and shoot (perfect antibodies). Our current ability to tailor a changing response to attacks from invaders by means of antibody synthesis may be largely responsible for our survival to date, and is used against a whole range of infections and the like. And it is probably due to having to deal with the handiwork of viruses- not now, as humans, but back in the primal by-and-by, in the nuclei of single-celled organisms. But for a  multi-celled organism developing antibodies,  a quickly-mutating virus is a moving target, difficult to hit, somewhat like shooting at a hummingbird with a battleship, the little thing won’t sit still long enough to set up a firing-solution. No surprise, then, that viral forms are still with us.

Among all the single-celled individuals in the early seas, each virus  found a host somewhere, with the cells thereafter treating the genetic material from the virus as its own.

The results to the bacteria (within whose very genes the deception was perpetrated) of all this trial-and-error viral activity was uneven, as you would guess. Depending upon the dice, it ran the gamut from instantly fatal, to fatal soon, to fatal later but before reproductive maturity, to merely disabling, to harmless, to beneficial, to WOW, Madge, will you look at that! Lungs! And they breed true!

All the while, natural selection judged the virus on how effective it was at being beneficial for the host: the more successful the resulting form, the more potential hosts for the viral form that best utilizes it. The adaptations of both are continually optimized by their continuing adaptations to the adaptations of the other, as less-well optimized mutations sink in the gene pool. Over time, successful symbiots (virus and host) become better able to exploit the environment they occupy, and better suited to each other. Those forms which are less so, have a competitive disadvantage, and are out-competed by those which are more so.

The first  particular viral re-engineering of the bacteria’s DNA was accomplished for no particular reason at all, it was one of many random attempts. The surviving forms only accidentally provided some competitive advantage to the virus. Had conditions been different, the pH lower, perhaps, or temperatures changed differently, other forms would have made it instead. Yet, using the shotgun method, one of the mutations stumbled upon the capacity to produce a gene sequence that facilitated the joining together of two different bacteria somehow, so that a bacteria better-able to provide for the life-support functions of both, could; while another bacteria that was better able to provide for reproduction (including that of the virus), performed that function. Let each specialize for the two, and be henceforth one. Almost all mutations are fatal, and if a viable mutation didn’t critically benefit the virus AND the host more than other combinations, it bred-out. But if it led to an increase in hosts for the virus? We got a winner!

With much less atmospheric ozone in the early atmosphere to moderate the sun’s UV, the rate of mutation (at least near the surface), may have been breathtaking. Countless mutations occurred, maybe by-the-minute, at least at times. A few forms persisted for a while, and time passed, time to radiate and adapt, over and over, and over… fewer survived to dominate the Pre-Cambrian seas. Over time, new pairs were adapted to work with others, then pairs with different pairs, then fours with fours, and fours with a two and a three, and a nine with a four, and so on.

Some worked less-well than others. Even while countless mutations were still occurring,only a few forms out of many  persisted , fewer survived to dominate.

Under those conditions, it should not be surprising that many, many forms, a hundred-trillion combinations, among them a form that might someday develop into a clam, and another a fish (or a methane-breathing tennis racket, for that matter) might have eventually been tried, to persist for a while, and to further radiate and adapt, some forms (including your own) surviving to dominate, to cover the entire planet(!), based solely upon the competitive advantage it provided – to the virus.

Invaders from space? Old news, we walk within you.

For more on the virus, see: http://anukp.wordpress.com/2007/01/21/virus-2/