Lamarck vs. Darwin

Jean-Baptiste Lamarck (1744-1829) deserves credit for bringing about a shift in scientific thought about the evolution of life––from judgments based on theological absolutes to inquiries into connections and causes. He conceived the idea that species change over time, and that all organisms are related––essentially the first explicit theory of evolution.

Unfortunately, Lamarck is best known for his now-discredited idea of inheritance of acquired characteristics, which maintained that experiences of an organism could be passed on through inheritance. In other words, if an organism worked at something desirable, its offspring would inherit the fruits of that effort.

Darwin liked Lamarck’s ideas about relatedness and change. They fit with his own theory that the accumulation of small changes could accomplish big results. And although Darwin had no explanation for why organisms varied and therefore couldn’t rule out the possibility that acquired characteristics were inherited, he felt certain that evolution was not driven by the desires of organisms. Organisms change continuously. Those who coincidentally experience changes that better fit them to their environment have more offspring, and so their kind survives and flourishes.

The perspectives of Lamarck and Darwin differ fundamentally on the matter of purposeful design. Lamarck, while accepting change, couldn’t drop the notion of a preordained plan behind evolution. Darwin saw natural selection as a powerful force, lacking a purpose, but creating the illusion of a planned goal.

Darwinism has decisively triumphed over Lamarckism. Lamarck's hypothesis of inheritance of acquired characteristics was refuted by August Weismann's mouse experiment: Weismann removed the tails of mice and bred the tailless mice, producing new generations of mice with normal tails. Evidence accumulated during the last fifty years has firmly established the generalization that information in living system flows one way: from DNA to RNA to protein; there is no way the environment can influence that organism’s proteins to change its DNA.