Darwinism applied to the coronavirus
Audio 02:41
Charles Darwin was a 19th century naturalist.
© Public domain
By: Florent Guignard
8 min
The English variant of the coronavirus is colonizing Europe, because it is more contagious.
An illustration of natural selection, a universal law for all living organisms discovered by the English naturalist Charles Darwin in the 19th century.
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A specter haunts Europe: that of the English variant of SARS-Cov-2, a mutant that continues to gain ground, because it is contagious for longer.
In France for example, it is now responsible for a large third of the cases of Covid-19.
A phenomenon of natural selection which gives it an undeniable advantage over the historical strain of the coronavirus.
"
Mutations, which are extremely numerous in viruses, occur at random,"
explains Alexandre Hassanin, researcher at the National Museum of Natural History in Paris.
But they are selected, in particular because they confer an advantage to the viruses, compared to the contamination.
Variants which will be more contagious will be selected from populations of the virus.
"
It is the law of the strongest, and of natural selection, at the heart of the theory of evolution developed by the English naturalist Charles Darwin in the 19th century.
And the more we reproduce, the more chances we have to evolve.
For humans, it is obviously much slower than for viruses.
"
Because the generation is longer, and because we have relatively few babies in general in the human species, it takes hundreds or thousands of years before a selection takes place,
specifies Mylène Weil. , research director at CNRS.
It is not at all the same timing for mosquitoes and even more so for viruses.
"
Mosquito tactics
Some species of mosquitoes can produce ten generations per year.
And this is how they have, in just a few years, developed resistance to insecticides, whatever their species, wherever they live, as Mylène Weil has shown in her work. at the Institute of Evolutionary Sciences in Montpellier.
“
The beneficial mutation, this resistance to insecticides, allows them to survive where other mosquitoes that don't have the mutation will die.
Those who survive will pass this mutation on to their offspring.
So this mutation will tend to spread.
"
The same evolution observed in different species, or in the same species but in different places, is called a convergent evolution.
A phenomenon that also concerns the three variants of the coronavirus, English, Brazilian and South African.
A similar mutation on three continents, thousands of kilometers away.
In the animal world, one of the most striking examples of convergent evolution concerns the shark and the dolphin.
Two very distant species (the first is a fish, the other a mammal) which have nevertheless developed the same morphology to move in the sea. “
These common points are linked to the adaptation to the environment in which these two species evolve, that is to say the aquatic environment,
notes Alexandre Hassanin.
When you are a vertebrate, there are ultimately not 36,000 ways to swim!
"
“Is evolution always irreversible? "
Not necessarily.
Evidenced by the story of the birch moth, a nocturnal butterfly with white wings that merge with the bark of birch trees, which allows it to be invisible to predators.
But in England, in the middle of the 19th century, at the time when Darwin published
The Origin of Species
, the industrial revolution was in full swing, and coal dust made the bark of birch trees black.
The birch moth, which lives only a week, will very quickly display black wings, to continue to escape predators.
A color change that will last a century.
When the British government adopts anti-pollution measures, the coal dust disappears from the landscape, the birch trees turn white again, just like the wings of the butterfly.
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