What Darwin didn’t know: viruses and evolution
Posted: 12 June 2009 02:21 AM   [ Ignore ]
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Viruses, the ubiquitous biological entities which “infect” all life from bacteria to humans, are now considered as playing an important role in evolution. When Darwin proposed his Theory of Evolution 150 years ago, viruses have not been discovered.

Here is an interesting article on research at the University of Cambridge

Perhaps one of the most unexpected findings has been the discovery of the degree to which viruses have been an evolutionary force, as witnessed by the accumulating genetic and immunological evidence of the ancient battles between viruses and their hosts.

The latest concern is the global pandemic of the H1N1 zoonotic swine flu virus:

Recent examples of this type of zoonotic transfer include the pig-to-human transmission of swine flu virus and the bird-to-human transmission of avian flu virus, both of which have raised global concerns regarding new human flu pandemics.

How do these viruses evolve to enable them to cross between species? What complex series of events is required for the virus to infect humans and sustain infections at sufficient levels in a new species to become readily transmissible within a new population? Why are some individuals protected from developing full-blown disease despite being infected? These are the sorts of question that interest scientists in the Laboratory of Viral Zoonotics. This line of research involves the application of new molecular technologies to address aspects of zoonotic infections of importance to both veterinary and human health.

Then, there are the amazing retroviruses:

Of particular interest to the team is a family of viruses known as the retroviruses, so named because of the ‘reverse’ way they reproduce themselves. Once a retrovirus has infected a cell, its RNA genome is replicated, or ‘reverse transcribed’, into DNA. This becomes integrated into the genome of the infected cell, so that it is copied every time the infected cell divides.

Sequencing of the human genome has revealed that retroviral integration has in fact been ongoing for millions of years. Human genomes, and those of other mammals, are littered with retrovirus-like elements as remnants of virus integration.

And the insidious stealth viruses:

Linked to this area, a major effort in the lab is focused on identifying new types of virus that have adapted so well to their hosts that they have gone unnoticed under normal circumstances in healthy individuals. These viral infections may circulate within the human population without causing overt disease yet, subclinically, influence our daily health and wellbeing; moreover, if associated with other infections, such as those that cause hepatitis, these viruses may accelerate or alter the course of the disease.

All this points to viruses as the champions of survival for 3.5 billion years in the evolution of life on earth. All life can be considered as hosts for viruses to propagate and survive.  As Dr. Spock would say, “live long and prosper”.  LOL

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Posted: 12 June 2009 06:40 AM   [ Ignore ]   [ # 1 ]
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But in survival terms, the virus must allow something else to live, so they cannot really win the battle in any meaningful way. I would hate to be the species they choose to let live.

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Posted: 13 June 2009 01:51 AM   [ Ignore ]   [ # 2 ]
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traveler - 12 June 2009 06:40 AM

But in survival terms, the virus must allow something else to live, so they cannot really win the battle in any meaningful way. I would hate to be the species they choose to let live.

Quite so, and we are among the species they chose to let live. However, the notion that viruses are mostly pathogenic is false. The latest research indicates there are many viruses which “infect” and allow the host to live, reproduce and thus co-evolve with the host. Here is an interesting article, “Can Viruses Make Us Human?” by Luis P. Villarreal

This question will seem preposterous to most. Viruses are molecular genetic parasites and are mostly recognized for their ability to induce disease in their host. Their effect on host evolution has long been thought to be like that of a predator on its prey, eliminating the host with weakened defenses. How can we propose any constructive role for viruses? Many viruses, however, can infect their host in a stable and persisting manner, generally with no disease, often for the life of the host. Such viruses can bring to bear onto their host the viral seeds of genetic creation. For such persisting viruses to successfully colonize their host, they must superimpose a complex viral molecular genetic identity onto their host. This essay will develop and present the argument that such stable persisting viruses represent a major creative force in the evolution of the host, driving the host to acquire new, and accumulate ever more complex, molecular identities. Based on this premise, this essay will examine the possible role of viruses in the evolution of complexity, including the evolution of human-specific attributes. This view of human evolution is part of a larger idea, that stable persisting viruses (genetic parasites) can allow the host to acquire complicated functions (complex phenotype) in one punctuated event of colonization. Such a process can now be considered as a possible explanation for several major dilemmas in evolutionary biology. All these dilemmas involve the origin of various host lineages that have acquired a complex and interacting set of functions in a relatively short time frame. Such acquisitions of complexity have always been difficult to explain by a simple Darwinian process. These dilemmas include the origin of the eukaryotic nucleus, the origin of flowering plants, the origin of the adaptive immune system in animals, and the origin of live birth (viviparous) placental mammals. In this essay I will only briefly consider the origin of the eukaryotic nucleus as an example of how persisting viruses can contribute to the evolution of complex host.

Defining fitness:

If we instead define fitness as the genetic contribution to an individual’s continued life, and the continued life of its decedents, we have a definition that is more similar to that originally used by Darwin. Such a definition would encompass fitness resulting from high rates of reproduction as well as long life. In the context of a persisting genetic parasite, we can reason that the parasite must increase the survival time of the virus or host to allow the attainment of a high probability of viral continuation or transmission.

So, Dr. Spock’s “live long and prosper” is apt as a description of fitness to survive.  smile

[ Edited: 13 June 2009 03:02 AM by kkwan ]
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Posted: 13 June 2009 05:34 AM   [ Ignore ]   [ # 3 ]
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kkwan - 13 June 2009 01:51 AM

So, Dr. Spock’s “live long and prosper” is apt as a description of fitness to survive.  smile

[nitpick]You mean Mr. Spock ... Dr. Spock wrote about child health and psychology. Different Spock.[/nitpick]

wink

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Posted: 13 June 2009 02:23 PM   [ Ignore ]   [ # 4 ]
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dougsmith - 13 June 2009 05:34 AM
kkwan - 13 June 2009 01:51 AM

So, Dr. Spock’s “live long and prosper” is apt as a description of fitness to survive.  smile

[nitpick]You mean Mr. Spock ... Dr. Spock wrote about child health and psychology. Different Spock.[/nitpick]

wink

You are correct. My apologies for ascribing the Spockian salute to the other Spock. For some strange reason, I somehow got the impression that Mr. Spock, being the Science Officer in Star Trek, should have been at least a PhD.

http://en.wikipedia.org/wiki/Spock

In The Making of Star Trek (1968), Roddenberry noted that he had been looking for an alien-sounding name, and didn’t know until later of Dr. Benjamin Spock, the renowned child psychologist.

grin

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Posted: 24 June 2009 10:20 PM   [ Ignore ]   [ # 5 ]
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Darwin didn’t know who the main characters (the common ancestors) were in his story of evolution. So he certainly couldn’t know what they were capable of breeding.  And a badly written fiction story doesn’t make a good true story.  wink

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Posted: 24 June 2009 11:29 PM   [ Ignore ]   [ # 6 ]
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Carico - 24 June 2009 10:20 PM

Darwin didn’t know who the main characters (the common ancestors) were in his story of evolution. So he certainly couldn’t know what they were capable of breeding.  And a badly written fiction story doesn’t make a good true story.  wink

Have you actually taken the time to READ Darwin’s book, or are you spouting the nonsense someone else has handed to you?

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Posted: 25 June 2009 04:15 PM   [ Ignore ]   [ # 7 ]
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It’s silly to criticize any first insights into scientific realities when there is a great deal of far more recent research that has corrobated, polished and verified the initial work.  Don’t waste our time criticizing Darwin, Carico, until you have read the volumes of work done in the last twenty years validating and proving Darwin’s seminal contentions.

Occam

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Posted: 12 July 2009 01:41 PM   [ Ignore ]   [ # 8 ]
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I didn’t read it but I have listened to Darwin’s Origin of the Species on audio books.

I was surprised and amazed at what length’s Darwin went to to outline the limits to his knowledge.
Also to present reasonable arguments against his proposition.
Some he very eloquently answered and others he acknowledged as requiring more study.

A study of Darwin’s writing is a study in the scientific process at its human best.

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Posted: 12 July 2009 01:53 PM   [ Ignore ]   [ # 9 ]
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But back to viruses and evolution.

I’ve been hearing an amazing fact being touted around these past couple years.
Apparently, on the order of 90% of the cells in your body are germ cells.
    Upon hearing this I thought impossible, but then I thought thank providence that germs are so much smaller than bodily cells.

The complexities to this web of life are truly spectacular.

And this brings me back to the Swine Flu thing and a recent report in NewsDaily.com:

LONDON, July 9, 2009 (Reuters) —
There is a growing risk that pigs will catch the new H1N1 flu strain—commonly known as swine flu—
from humans, German researchers said on Thursday.

~~~

Widespread transmission from people to pigs could mix up virus strains further,
leading to unpredictable changes in the disease.

~~~

Germany’s national research center for animal health, experimentally infected five pigs with the new flu.
Four days later, the virus had spread to three uninfected pigs housed with them and all the pigs showed clinical signs of disease,
they reported in the Journal of General Virology.

~~~
This quote I love:

Encouragingly, though, while the virus spread quickly among the pigs, it did not spread to five chickens housed with them.


as that forgotten song says: the road goes on for ever and the party never ends…......

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Posted: 12 July 2009 02:02 PM   [ Ignore ]   [ # 10 ]
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Evolution is not real…god is doing it!!

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Posted: 12 July 2009 02:30 PM   [ Ignore ]   [ # 11 ]
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I don’t know.  This sounds pretty dicy to me.  And, as we know, god does not play dice.  LOL

Occam

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Posted: 04 August 2009 09:23 PM   [ Ignore ]   [ # 12 ]
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Occam - 12 July 2009 02:30 PM

I don’t know.  This sounds pretty dicy to me.  And, as we know, god does not play dice.  LOL

Occam

I used to believe that too
until I saw this great book,
I think it was part of some TimeLife series.
“Molecules”

This book displayed and described, I don’t remember 50 - 100 of the most common molecules.

Looking at that pageant of steadily increasing molecular chains, with their various additions and duplications of simpler molecules,
I thought Holy Moly!
The heck God wasn’t playing dice! 

Just a tossing them molecules ....
just to see which would click….
and what would do what

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Posted: 08 August 2009 09:20 PM   [ Ignore ]   [ # 13 ]
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Darwin was a true and masterful scientist in that he observed, catalogued and applied honest reasoning to his findings while, as earlier pointed out, he also reported on possible open subjects for further speculation.  Such is a far cry from much of the agenda driven “science” one often comes across today.  That viruses could not be observed in Darwin’s day does not exclude them from taking their natural place in the catalogue of evolving life forms and as also pointed out, our recent understanding of such microforms shows a mechanism for hastening evolution in general by their acting directly to induce changes on a cellular level.

I also suspect that Darwin understood or at least speculated much about parasitic and symbiotic superorganisms and the ultimate potential for a continuing form of evolution through these inter-organism relationships, given such could easily be considered a logical extention of the principle of natural selection.  Less recognized in his time perhaps is the effect of mutations which may result from exposure to various forms of radiation such as solar, cosmic or elemental.

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