Rich in counterintuitive observations, the study of evolution is often misunderstood. We focus here on widespread ideas that happen to be patently false.
LAUSANNE —Of all the scientific fields, evolution probably carries the most common misconceptions. Who, for instance, has never heard that humans descend from apes? Or that only the strongest organisms survive? Although widespread, these beliefs are nevertheless completely false.
"It's only a theory"
Many believe evolution is simply a theory, an opinion like any other. But "there is no doubt about the fact of evolution," says Laurent Keller, a biologist from the University of Lausanne, in Switzerland. "Fossils prove that species have disappeared, while current species have not always existed." The misunderstanding could well come from the ambivalence of the word "theory." It implies a personal and speculative idea. But for scientists, a theory designates an explanatory framework that allows them to understand natural processes. As such, the theory of evolution is a real scientific theory, and not just a simple intuition that Charles Darwin once had.
"Evolution is not observable"
We often assimilate evolution processes to events happening over millions of years. "Wrong," says the University of Lausanne's Tania Jenkins. "The resistance of bacteria against antibiotics is proof that organisms can evolve over much shorter periods of time." Insects, viruses, bacteria. Every organism capable of reproducing at high speed generally evolves rapidly. The influenza virus, which returns every year in a slightly different form, is proof of this.
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Darwin 200-year anniversary coin. Photo: CGP Grey
"It's for atheists"
Is it necessary to put aside religious beliefs to accept the theory of evolution? "There's no need to choose," assures Héloise Dufour, co-organizer of Lausanne, Capitale de l'évolution. "The theory of evolution explains the world around us but doesn't say anything about beliefs or the existence of God," she says. Evolution and religion actually coexist well, she says, especially "in Switzerland, where most religious people accept this scientific theory."
"Evolution means improvement"
We've all seen those T-shirts that display an image meant to illustrate evolution: a small, quadruped monkey walks to the right, progressively standing up straight to eventually become a splendid Homo sapiens as straight as a rod. What this implies is that evolution is synonymous with progress, strengthening and more efficient organisms.
But in reality, the characteristics conserved by natural selection are not always beneficial, as Laurent Keller explains. "A profitable characteristic for an individual can sometimes prove to be harmful for the population in the long term. Consider, for instance, that some male birds have a longer tail than others. While they are better at attracting females, they can't fly as well. The result is that they reproduce more easily but also pass this characteristic to their offspring. "And, in the end, all birds will not fly as well," Keller explains.
"Humans descend from apes"
Is the chimpanzee our ancestor? The scenario is tempting: Little by little, the monkey straightened up to become the biped we are today. But this scenario is a naïve depiction and not a scientifically proven fact. First of all, the chimpanzee species, which appeared eight million years ago, is as recent as ours. "It's not our ancestor but rather our cousin," says the University of Avignon's Ivan Scotti.
But what about the 99% of genomes that we have in common? This doesn't prove it is our ancestor. After all, two brothers share a good part of their DNA without one of them descending from the other. "We do have a common ancestor with the chimpanzee, but it was neither a monkey nor a human," Keller adds. "We don't exactly know who we descend from."
"Life evolves randomly"
How do new characteristics that will consequently be preserved — or disappear — appear during evolution? Through genetic transformations, an eminently random process. With this in mind, it's tempting to think evolution relies only on chance. But only the "good" transformations, those that allow the organism a better adjustment to its environment, are conserved," Keller says.
In other words, transformations are random, but the processes through which they are kept or not (which is known as natural selection) has nothing to do with chance. In this way, the most complex characteristics observed in nature did not appear by chance. They are the result of a selection that favored the most well-adapted individuals most likely to reproduce.
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Enjoy the ride! Photo: Kevin Dooley
"It's a search for the origin of life"
No, the theory of evolution doesn't aim to explain the origin of life. Not just that, anyway. "It's a question among so many others that we ask ourselves," Keller says. "But it's not more important than the origin of sexual organs, proteins, aging, etc. It's a very broad subject."
"Humans have stopped evolving"
Another common but false idea is that by controlling the environment so much, mankind freed itself from evolutionary pressure. But our recent genetic history proves that we are evolving, as the appearance of lactose tolerance shows. Originally, humans became intolerant to this sugar present in milk a few months after birth. But a transformation that occurred in an individual in Africa some 8,000 years ago changed things, making lifelong lactose digestion possible.
Biologists believe that this transformation could have been selected because populations living at that time had to consume lots of fresh milk to survive. Incapable of digesting the only nutrient at their disposition, those intolerant to it would have perished.
"A theory that legitimizes racism"
The notion that the theory of evolution justifies the superiority of certain individuals over others, opening the way to racism, is an absurdity that Ivan Scotti dismisses. "If it's true that natural selection sometimes favors competition between individuals, what about when it favors cooperative behaviors, such as when birds work together to build their nests, or when ants renounce on reproducing to clear resources for the sole reproduction of the queen?"
Doctrines advocating competition between races or social classes, which are gathered under the term "social Darwinism," have no scientific meaning, he says.
"The study of evolution is useless"
"It's quite the opposite because evolution is everywhere in our everyday lives," says Tania Jenkins. "If we have such a diversity of cheese, beer or wine, it's thanks to the diversity of bacteria, yeast and fruit!"
And practical applications exist: We are currently seeing the emergence of "Darwinian" medicine, in which treatments that take into account the evolution of humans and germs, which have gone through their own adjustments, are being developed. All this, doctors hope, should make it possible to study illnesses under a new light.