Darwinism vs. Lamarckism: Understanding Evolutionary Theory

Lamarckism: Key Principles

Jean-Baptiste Lamarck proposed a theory of evolution based on the following principles:

• There is a gradual progression from simpler organisms to more complex forms.
• The mechanism by which gradual changes occur is adaptation to the environment through the use and disuse of certain organs.
• The exercise of an organ produces its development and perfection.
• Inherited acquired characteristics can easily be adapted to environmental conditions.

Darwinism: The Theory of Natural Selection

The Voyage of the HMS Beagle

Charles Darwin embarked on the HMS Beagle for a trip around the world. His mission on board consisted of collecting exotic plants and animals. The trip lasted 5 years, and by the end, Darwin found evidence of the variability of species.

Key Influences on Darwin's Theory

Two key findings influenced his discovery:

• The observation of extinct mammals (fossils).
• The cataloging of different species of finches on the Galapagos Islands.

Development and Publication

Upon his return to England, Darwin reflected on the findings to develop a scientific explanation. The studies undertaken in the archipelago led to the discovery of Natural Selection as a key element of the evolutionary process. This theoretical development was of great importance.

Alfred Russel Wallace later questioned whether Natural Selection alone was sufficient to account for human origins.

Darwin published the book On the Origin of Species. Its publication caused much controversy. However, the evidence gathered by Darwin was so compelling that the theory of evolution gradually gained momentum, accumulating a larger body of evidence until it finally achieved acceptance by the scientific world.

The Mechanism of Natural Selection

Darwin theorized that a struggle for survival is established in all species because there are more organisms than available resources, which drives the process of Natural Selection.

As a result of this struggle—whether between individuals within the same species or different species—for limited resources (food, sexual partners, space, etc.), the fittest survive. Those individuals possessing the characteristics best suited to their environment thrive, while the least fit disappear over time. This theory superseded Lamarck's theory.

Conclusion: Darwin vs. Lamarck

Biological evolution is thus explained primarily by a process of Natural Selection, and not solely through a process of adaptation to the environment, since variation originates within the living being itself and is not solely dictated by the medium in which it develops.