Avian Flu: An Example of Evolution? - Evolution News & Views

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Avian Flu: An Example of Evolution?

There has been a lot of talk lately about the Avian (i.e. Bird) Flu, and how it's a new virus which has sadly killed a few dozen people and millions of birds. This post will briefly assess whether the Avian Flu is an example of evolution, and also assess the implications for the origin of new genes and biological structures.

Our immune systems are engaged in an eternal arm's race, or perhaps better put, a cat-and-mouse game, against pathogens like viruses. Viruses are trying to hijack our cells' machinery to make more copies of themselves. When they succeed, our cells can become damaged or destroyed.

Our bodies respond by generating antibodies which can attack these viruses and stop them. But our immune systems are based upon a "memory": they can only target pathogens which resemble ones they've seen before. If our bodies must contend against something new or highly different, our immune systems have to try generate new types of antibodies until one does the trick and stops the virus. If we can't generate the right antibody in time, the virus wins, as has unfortunately happened to nearly 60 people who have been infected by the Avian Flu.

The origin of the Avian Flu is indeed an example of evolution. However, as many of us learned in school, evolution can simply mean change over time. Scientists suspect that this new "Avian Flu" strain of the flu virus arose because two flu viruses (probably one previously in humans, and another in birds), swapped genetic material in a process known as "reassortment."

This reassortment thus happened when there was a coinfection of two viruses in the same cell, and then the resulting viruses that came out were a mixture of the genes in two different viruses. This process is analagous to horizontal gene transfer, which has been identified in bacteria as a way for spreading antibiotic resistance. This link provides an excellent graphical illustration.

So our fight to combat the Avian Flu is undoubtedly a fight against evolution. The question is, has there been a net increase in genetic information through this "evolution"? The Avian Flu is essentially the swapping of genes--but its genes probably came from other pre-existing viruses.

One new twist on the Avian Flu is that it can infect organs other than the lungs and cause damage to greater parts of our bodies. This more widespread attack has caused some fatalities. The fact that the Avian Flu can activate this protein in other places probably has something to do with its new configuration of genes. But we're really not dealing with anything new.

Viruses are always mutating to avoid detection by our immune system by becoming something that current antibodies can't recognize. Thus, many viruses survive by having extremely high mutation rates. However, viruses only mutate at a certain rate or they will mutate themselves into oblivion.

Thus, there are limits to the amount that viruses can mutate. When they breach this limit they will experience "error catastrophe." Even virus populations which don't breach this limit can experience permanent fixation of deleterious mutations. Indeed, some scientists are trying to create vaccines for HIV by targeting viruses in the very sites where they can't mutate. The limits are wider than what our immune system can handle at any given time and often when we are sick, it is because a virus has mutated into something our immune system cannot immediately target. But still, even the evolution of viruses has limits. Some researchers have called this the "mutation limit."

The reason that the Avian Flu is succeding thus far is because when the two previously-existing viruses swapped some genetic material and created Avian Flu strains, its current configuration is different enough from microbes our immune systems can already target that many people are unable to fight off the virus.

But it's evolution within limits, and it's evolution that generally uses pre-existing genetic material. After all, the current strains of the Avian flu are nothing more than viruses, which are descended from nothing more than a line of billions upon billions of generations of viruses, which, as far as we can tell, have always been viruses, and aren't becoming anything other than more viruses.

Viruses are masters at taking what already exists and swapping it around to dodge our immune system. And that's what has happened here. It's still a virus, and there's probably nothing "new" in terms of new genes. This does not show that evolution can create new genetic information.

But there's good news. Scientists are working on creating antibodies. In fact, perhaps you, the reader, already have the cure within you.

What does this mean for intelligent design theory?
Some people have alleged that the evolution of new viruses poses some kind of a challenge to intelligent design. As illustrated above, design proponents do not question the possibility that populations can evolve, especially when it is microevolution within fixed limits.

Intelligent design is concerned with the origin of novel biochemical pathways and new complex biological features. But intelligent design freely grants that pre-existing specified complexity can be swapped around among different organisms (see William Dembski's No Free Lunch or his webbed article, Searching Large Spaces: Displacement and No Free Lunch Regress). That seems to be precisely what created the Avian Flu: pre-existing viral genes through a natural process of “gene swapping” were combined in a new way to create the Avian Flu virus.

Some have alleged that because viruses cause death, that therefore they could not have been designed. (i.e. it is “malicious design”) As a scientific theory, intelligent design says nothing about philosophical questions like the moral purposes of a designed object. Intelligent design theorists have observed, after all, that even objects which are designed to kill (i.e. guns, bombs) are still designed. Thus, the "morality" or "moral purpose" of an object tells you nothing about whether or not it was designed.

This is thus a theological objection to design pertaining to the “problem of evil.” Theological questions require theological answers, which are outside the scope of design theory. However, nearly every religion has a different way of trying to cope with the problem of evil. Those religious answers will not be explored here, but suffice to say, for those concerned with the theological problem of evil, there are plenty of answers out there.

Conclusion
In conclusion, viruses are constantly trying to out-evolve your immune system. That's how they survive. All they can do is mutate certain non-essential portions of their DNA within a mutation limit, and try to acquire other pre-existing genes to create combinations your antibodies haven't seen before. But in the end they're still always viruses. Our immune systems are generally pretty good at keeping up with them, but just in case, it never hurts to give yours a boost, so don't forget to get your flu shot!