Wed 08 May 2019
Red Queen Race
Tags: biology evolution antibiotics
When I was a kid, I was perturbed at the outbreaks of new diseases. There was no Swine Flue before twenty first century or HIV before tenth century. Why nature was hell-bent in pulling diseases out of a hat everytime humans make progress in science?
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Naively I belived that new diseases were nature's way of pushing against human's advancement in science. Nature had to ensure that human's dont overflow the planet. I belived in Rita (Sanskrit ṛta ), a cosmic order of the universe. The wheel of dharma(duty) & karma (accumulated effects of good and bad actions) somehow illusioned to maintain harmony in the world. But evolution shattered my perception of reality.
A famous poem “In Memorial A.H.H” by Lord Alfred Tennyson tries to reconcile with the violent natural world
Who trusted God was love indeed
And love Creation's final law
Tho' Nature, red in tooth and claw
With ravine, shriek'd against his creed
Darwinian nature’s is not beingn. Natural selection, the chisel of nature, leads to increase in frequency of genes (allele) which are more reproducible. Thus both prey or predators evolve in a arm race to counter each other. But not all evolution benefit the species.
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A classic case of blind cave fish shows how evolution lacks any ultimate purpose. Over the past few million years, blind forms of the Mexican tetra (Astyanax mexicanus) have evolved in caves. The fish subsequently have lost their eyes after mutations disabled key genes. This trait helped fish to save energy.
The reason new diseases outbreaks is due to fast generic mutation of the pathogens. It’s estimated that evolution of a bacteria in a day is equivalent of evolution of human in thousand years. That is the reaons why many antibiotic become useless after certain amount of time example staphylococcal bacteria was very vunerable to penicillin in 1941. Currently ninety five percent of staphylococcal bacteria are resistent to penicillin1.
Lewis Caroll was not only a world famous children’s writer but also a mathematician. Hence it’s not surprising to find intriguing logics in his writings. One such writing that I stumbled upon was an incident that appears in Lewis Carroll’s Through the Looking-Glass.
"Well, in our country," said Alice, still panting a little, "you'd generally get to somewhere else—if you run very fast for a long time, as we've been doing."
"A slow sort of country!" said the Queen. "Now, here, you see, it takes all the running you can do, to keep in the same place. If you want to get somewhere else, you must run at least twice as fast as that!"
Leigh Van Valen, an evolutionary biologist, proposed Red Queen hypothesis that captures arms race between co-evolving species. Coevolution leads to situations where the probabily of extinction is relatively constant over millions of years(Van Valen 1973). In tightly coevolved interactions, evolutionary change of one species could lead to extinction of other species. The longer evolutionary history is neither better adopter or less adapted. So evolution doesn’t have a progressive quality. The species thus have to run(evolve) to remain in the same place (extant)2.
I wonder about the arm race between humans and pathogens. Will we evolve to develop invincible defense mechanism against pathogens? Or will the human race plumment to its tiniest microscopic foe? Most pathogens eventually develop resistance against antibiotics. World Health Organization have classified antimicrobial resistance as a “serious threat [that] is no longer a prediction for the future, it is happening right now in every region of the world and has the potential to affect anyone, of any age, in any country”3.
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