Darwin vs Lamarck: Evolution and Scientific Revolution

In 1809, a French naturalist published a book that would change how we see life itself. Jean-Baptiste Lamarck stated a revolutionary idea: species are not fixed, they transform over time. That same year, a child was born in England. His name was Charles Darwin. Fifty years later, he would publish another theory of evolution - the one that would triumph.

The history of science often remembers Darwin as the “father of evolution” and relegates Lamarck to the status of a quaint error with his giraffe stretching its neck. This view is unfair. Lamarck was a visionary pioneer; Darwin, a brilliant synthesizer. Together, they laid the foundations of modern biology - even though their paths diverged profoundly.

Comparing Lamarck (1744-1829) and Darwin (1809-1882) means understanding how a revolutionary idea - the evolution of species - emerged, matured, and ultimately transformed our worldview. It’s also a lesson about science itself: how theories are born, confront each other, and evolve.

Two Lives, Two Eras

Lamarck: The Forgotten Pioneer

Jean-Baptiste de Monet, Chevalier de Lamarck, was born in 1744 into a family of minor Picardy nobility. The eleventh child, destined for the Church, he chose the army upon his father’s death. Wounded in the neck during the Seven Years’ War, he had to abandon his military career. He was 22 with no clear future.

It was almost by chance that he turned to natural sciences. Passionate about plants, he studied botany for ten years and published in 1778 a “French Flora” that earned him entry to the Academy of Sciences. Buffon, the great naturalist of the time, took him under his wing.

The French Revolution upended his life. In 1793, the King’s Garden became the Museum of Natural History, and Lamarck, at 49, found himself professor of… invertebrates. A field he didn’t know. He studied it relentlessly and became the world’s greatest specialist on animals without backbones - a term he invented himself.

It was while classifying thousands of fossil shells that Lamarck was struck by an obvious fact: species changed. From one geological layer to another, forms gradually transformed. Species were not immutable, created once and for all by God. They evolved.

In 1809, in his “Zoological Philosophy,” he proposed the first complete system explaining evolution. Organisms, he said, transform under the effect of two forces: a natural tendency toward complexity, and adaptation to circumstances through use or disuse of organs.

The idea was poorly received. Cuvier, the most powerful naturalist of the time, ridiculed it. Napoleon humiliated Lamarck during an audience. The scientific community remained skeptical. Lamarck died in 1829, blind, poor, forgotten. His daughter dictated the funeral eulogy: “Posterity will admire you, it will avenge you, my father.”

Darwin: The Gentleman Naturalist

Charles Darwin was born in 1809 into a wealthy family of doctors and industrialists. His grandfather, Erasmus Darwin, was an original thinker who had himself speculated about evolution. Charles grew up in comfort, surrounded by books, gardens, naturalist collections.

A mediocre student in medicine (he couldn’t stand the sight of blood), then in theology (without much conviction), he was mainly passionate about hunting, beetles, and geology. It was almost by accident that he embarked, at 22, on HMS Beagle for a scientific voyage around the world.

Those five years (1831-1836) transformed his life. Darwin observed, collected, noted. In South America, he discovered fossils of extinct giant mammals. In the Galápagos Islands, he noticed that each island had its own species of finches and tortoises. Why so many variations? Why these resemblances between neighboring species?

Back in England, Darwin meditated for twenty years. He accumulated evidence, consulted breeders, studied domestic pigeons, corresponded with naturalists worldwide. And above all, he found a mechanism: natural selection. The best-adapted individuals survive and reproduce more. Their characteristics are passed on. Slowly, species change.

He hesitated to publish - the idea was too explosive - when, in 1858, he received a letter from a young naturalist, Alfred Russel Wallace, who had discovered the same mechanism. Pushed by his friends, Darwin finally published “On the Origin of Species” in 1859. The book sold out in one day. The world would never be the same.

Darwin spent his last years deepening his theory, responding to critics, studying earthworms. He died in 1882, covered with honors, and was buried in Westminster Abbey, near Newton.

Two Theories: Lamarck vs Darwin

Lamarck’s Theory: The Inheritance of Acquired Characteristics

Lamarck proposed that evolution occurred through two main mechanisms. The first was a natural tendency toward complexity: life, he believed, had an internal drive toward ever more elaborate forms. This is why we observed a “scale of beings,” from simple to complex organisms.

The second mechanism was adaptation through use. Organisms, facing their environment, develop certain organs through repeated use and atrophy others through disuse. These modifications acquired during life are then passed on to descendants.

The giraffe example became famous - and caricatured. According to Lamarck, the ancestors of giraffes, by stretching to reach high leaves, gradually lengthened their necks. This acquired elongation was passed on to their offspring, generation after generation, until producing the current long neck.

This idea seems naive to us today. We know that acquired characteristics are not inherited: if a blacksmith develops his muscles, his children won’t be born more muscular. Yet Lamarck’s theory was consistent with the knowledge of his time. No one then understood the mechanisms of heredity.

It should also be noted that Lamarck was right about the essential point: species evolve. This was a revolutionary idea at a time when divine creation and the fixity of species were dogmas. Lamarck opened a door that Darwin would walk through.

Darwin’s Theory: Natural Selection

Darwin proposed a radically different mechanism. Evolution, he argued, doesn’t come from an internal tendency or individual efforts. It comes from variation and selection.

Individuals of the same species naturally vary among themselves. Some are taller, faster, more resistant. These variations are hereditary (Darwin didn’t know how, but he observed it). In the struggle for existence - for food, territory, mates - the individuals best adapted to their environment survive and reproduce more. Their characteristics spread through the population. Generation after generation, the species changes.

Let’s take the giraffe example again. For Darwin, there was naturally variation in neck length. In an environment where accessible leaves are high up, giraffes with longer necks have an advantage: they feed better, survive better, reproduce more. Their descendants inherit this tendency toward longer necks. Over millennia, the average lengthens.

The difference is crucial. In Lamarck’s view, the individual actively adapts and passes on its adaptation. In Darwin’s view, variation is random, and the environment “selects” the fittest. Evolution has no predetermined direction, no purpose. It is opportunistic, contingent, blind.

This vision was profoundly disturbing. It eliminated the need for a divine plan, for purpose in nature. Man was no longer the pinnacle of creation, but a product of chance and necessity. Darwin knew this and suffered for it.

Why Darwin “Won”

The Evidence

Darwin had a decisive advantage: evidence. For twenty years, he had accumulated a considerable mass of observations, experiments, testimonies. “On the Origin of Species” is an extraordinarily documented book, where every claim is supported by facts.

He showed how artificial selection - that of breeders and gardeners - could transform species in a few generations. If humans could create fancy pigeons or dogs of all sizes, why couldn’t nature do the same over millions of years?

He explained the geographical distribution of species, the resemblances between related species, vestigial organs (like the human appendix), transitional fossils. Everything became clear in the light of natural selection.

Lamarck, in comparison, had less concrete evidence. His theory was more speculative, more philosophical. It rested on brilliant intuitions but was difficult to verify experimentally.

The Scientific Context

Darwin also benefited from a favorable context. By 1859, geology had established the immense age of the Earth - millions of years, not a few thousand. Paleontology revealed extinct species, gradual transitions. The idea of evolution was “in the air.”

Lamarck, fifty years earlier, faced a scientific world still dominated by fixism. Cuvier, his opponent, explained fossils through “catastrophes” followed by new creations. The very idea of species transformation seemed absurd to most naturalists.

Genetics

The final blow to Lamarckism came from genetics. Mendel, Darwin’s contemporary, discovered the laws of heredity. In the 20th century, molecular biology revealed DNA, genes, mutations. We finally understood how characteristics are transmitted - and how they are not.

Acquired characteristics don’t modify genes. A bodybuilder doesn’t pass on his muscles to his children. Genetic mutations are random, not directed by the organism’s “needs.” Darwin was right: variation is blind, and selection does the sorting.

The “modern synthesis” of the 1930s-1940s merged Darwinism and genetics. Evolution through natural selection, acting on random genetic variations, became the central paradigm of biology. Lamarck was officially refuted.

But Lamarck Returns…

Epigenetics

In recent decades, a surprise has shaken certainties. Epigenetics has revealed that the environment can modify gene expression - without changing the DNA itself - and that some of these modifications can be passed on to subsequent generations.

Studies have shown that stress, diet, trauma can leave transmissible “epigenetic marks.” The grandchildren of famine victims sometimes carry metabolic traces of that famine. This isn’t exactly Lamarckism - the DNA doesn’t change - but it’s a form of inheritance of acquired characteristics.

Some biologists speak of “Lamarck’s return.” That’s exaggerated: natural selection remains the main engine of evolution. But Lamarck wasn’t completely wrong. The organism isn’t passive in relation to its environment. There are mechanisms by which lived experience can influence heredity.

The Complexity of Life

More generally, contemporary biology recognizes that evolution is more complex than “classical” Darwinism suggested. Genetic drift, horizontal gene transfer, symbiosis, self-organization play important roles. Evolution is not just “variation + selection.”

Lamarck sensed this complexity. His “tendency toward complexity” is no longer accepted as such, but the idea that evolution has preferred directions, internal constraints, is debated. Is evolution purely opportunistic, or are there “attractors”?

These questions remain open. Darwin won the 19th-century battle, but the war of ideas continues. And Lamarck, the forgotten pioneer, may still have things to teach us.

Two Personalities, Two Styles

Lamarck: The Isolated Visionary

Lamarck was a solitary thinker, a bold theorist. He loved grand syntheses, coherent systems, overall visions. His “Zoological Philosophy” is an ambitious book that attempts to explain all of life.

But this boldness worked against him. Lamarck sometimes speculated beyond available evidence. He had brilliant intuitions but also bizarre ideas (he believed, for example, that bodily fluids played a role in evolution). His opponents had no trouble ridiculing him.

He was also socially awkward. Cuvier, his rival, was a skilled politician who knew how to maneuver in circles of power. Lamarck alienated the powerful through his stubbornness and lack of diplomacy. He ended his life marginalized, bitter, misunderstood.

Darwin: The Cautious Methodical

Darwin was the opposite. Cautious, methodical, he accumulated evidence before advancing an idea. He anticipated objections and answered them in advance. His writing was clear, accessible, persuasive.

He was also an excellent communicator. He maintained massive correspondence with scientists worldwide, shared his doubts and discoveries, patiently built a network of allies. When “On the Origin of Species” appeared, he had already convinced many.

Yet Darwin suffered from chronic anxiety. He knew his theory would be controversial and dreaded attacks. He often delegated the public defense of his ideas to allies like Thomas Huxley (“Darwin’s bulldog”). He himself preferred to stay at his Down estate, observing his earthworms.

This caution was also a scientific virtue. Darwin recognized the limits of his theory, the unanswered questions, the difficulties. He didn’t claim to explain everything. This intellectual honesty strengthened his credibility.

Impact on Human Thought

Lamarck: The Idea of Evolution

Lamarck’s fundamental contribution is the very idea of evolution. Before him, most naturalists believed in the fixity of species. After him, the question was no longer “do species evolve?” but “how do they evolve?”

This idea had profound philosophical implications. If species change, humans too are the product of a history. We were not created as we are, we became what we are. This historical and dynamic vision of life transformed our conception of nature and ourselves.

Lamarck also helped secularize science. His theory didn’t need God to explain the diversity of life. Nature transformed itself by its own forces, according to its own laws. It was a metaphysical revolution as much as a scientific one.

Darwin: The End of Human Exceptionalism

Darwin went further. By showing that all species, including humans, descend from common ancestors through a blind process, he dealt a fatal blow to human exceptionalism.

We are not special creatures, fashioned in God’s image. We are animals among others, cousins of apes, descendants of fish, related to bacteria. This truth, disturbing to many, transformed how we see ourselves and the rest of life.

Darwin also provided a framework for thinking about behaviors, emotions, cognitive abilities. If our bodies evolved, so did our minds. Evolutionary psychology, sociobiology, cognitive sciences are rooted in this Darwinian insight.

The cultural impact was immense. Darwinism has been invoked - often abusively - to justify capitalism, racism, eugenics. It has also nourished atheism, ecology, animal rights. Few scientific theories have influenced human thought as much.

Conclusion: Two Revolutionaries, One Revolution

Lamarck and Darwin are not adversaries, but stages of the same revolution. Lamarck opened the way by affirming that species evolve. Darwin found the mechanism - natural selection - that explains how they evolve. Without Lamarck, Darwin would have had more difficulty getting the very idea of evolution accepted. Without Darwin, Lamarckism might have become the dominant theory, before being corrected by genetics.

The history of science is not a match with a winner and a loser. It’s a collective construction where fertile errors count as much as definitive truths. Lamarck was wrong about the mechanism, but he was right about what mattered. Darwin was right about the mechanism, but his theory continues to be refined, completed, sometimes questioned.

Today, we know evolution is more complex than either Lamarck or Darwin imagined. Epigenetics, gene transfers, symbiosis, developmental plasticity enrich the picture. Twenty-first-century biology goes beyond “classical” Darwinism - without abolishing it.

What remains is the fundamental idea: we are the product of a history. Species change, transform, disappear and appear. Life is a river, not a pond. This vision, born with Lamarck and triumphing with Darwin, is one of the greatest revolutions of the human mind.

And perhaps that’s the real lesson of this comparison: in science as in evolution, ideas are born, transform, fight and combine. The best survive - not because they’re perfect, but because they’re best adapted to explaining the world as we discover it.