Swine Flu and Darwinian Evolution: Is This Flu Strain Likely to Mutate into Milder Forms—or More Virulent Ones?

Two scientists appear to be saying contradictory things in a Los Angeles Times article on Swine Flu, but actually they are not. One scientist is quoted as saying that viruses tend to become symbiotic with their hosts:

As the virus adapts to its human hosts, it is likely to find ways of spreading more efficiently. But evolution also suggests it might become less dangerous, Olsen said.

“If it kills off all its potential hosts, you reach a point where the virus can’t survive,” he said.

This is Evolution 101, and it would seem to imply that the longer this particular strain of Swine Flu circulates, the less virulent it will become.

And yet the Los Angeles Times also quotes a second scientist who fears the prolonged survival of the Swine Flu virus through the summer:

Though scientists have begun to relax about the initial toll, they’re considerably less comfortable when taking into account the fall flu season. They remain haunted by the experience of 1918, when the relatively mild first wave of flu was followed several months later by a more aggressive wave.

The longer the virus survives, the more chances it has to mutate into a deadlier form.

“If this virus keep going through our summer,” Palese said, “I would be very concerned.”

Is this an example of dueling scientific opinion, so that those of us who are not scientists simply have no reliable information to go on?


Simply put: viruses go through long periods of relative boredom accompanied by short periods of terror. In other words, the first scientist is correct that the virus, as it circulates, may, in its most widespread varients, produce non-lethal illness (so as to not kill off its hosts). But as the virus goes through its reproductive cycle again and again, and varies and multiplies in more and more people, and survives through the summer, there is the danger that a highly virulent strain of the virus could evolve and suddenly hit in, say, one particular city or country, which might then spread via airlines worldwide.

In short, this is no time for complacency, for you can’t know the mutated Darwinian variant that may be coming your way (whether it takes on a mild symbiotic relationship to its host, or a virulent one). Evolution operates by trying a range of variations.

This was illustrated again in the Los Angeles Times article when it quoted Peter Palese a second time, saying:

“There are certain characteristics, molecular signatures, which this virus lacks,” said Peter Palese, a microbiologist and influenza expert at Mt. Sinai Medical Center in New York. In particular, the swine flu lacks an amino acid that appears to increase the number of virus particles in the lungs and make the disease more deadly.

Obviously, the fear is that, over the summer, as the virus mutates, not only milder strains, but more virulent ones, might develop (such as those that increase the production of virus particles in the lung).

In short, this is no time for complacency. Keep your hands clean and follow all other CDC recommended precautions. And don’t let sites like the Drudge Report, which have been downplaying the Swine Flu virus’s dangers with irony and mock alarm, effect your own health vigilance.

This is not a left-right political thing. This is a real health threat, and so an ounce of prevention here is worth a pound of cure. An overreaction, in this instance, is much better than a dismissive underreaction.

If there is any didactic lesson here it is that nothing in biology can really be fully comprehended without taking into account Darwinian evolution.

About Santi Tafarella

I teach writing and literature at Antelope Valley College in California.
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