Science Quote by Ernst Mayr

Ernst Mayr reduces the engine of evolution to two linked ideas Darwin articulated: heritable variation arises and selection sorts it. Nothing mystical is required beyond these processes, yet their simplicity hides enormous power. Variation supplies the raw material. Mutations, recombination, and gene flow generate differences among individuals in a population. Selection is the consistent bias in which differences are preserved, as some variants leave more descendants than others because of how well they fit their environment.

The word merely does not belittle complexity; it strips away teleology. Evolution needs no foresight, plan, or intrinsic drive toward progress. Outcomes are contingent, dependent on the starting variation and the historical and ecological circumstances that channel selection. The same functional challenge can yield different solutions if the available variants and past histories differ, which is why wings evolved multiple times yet with contrasting architectures, or why similar niches in different continents host distinct but comparably adapted species.

As an architect of the Modern Synthesis, Mayr emphasized population thinking over essentialism. Species are not fixed essences but dynamic populations where continuous variation matters. Darwin lacked knowledge of DNA, but the union of Mendelian genetics with natural selection confirmed that heritable variation plus selection suffices to explain adaptation and diversification. Other processes, such as genetic drift, developmental constraints, and pleiotropy, also shape trajectories, but without variation to test and selection to filter, evolution would stall.

Seeing evolution as contingent on variation and selection refocuses attention at the right scale. Traits are not crafted for purposes; they persist because they worked better than alternatives in particular contexts. Fitness has no absolute measure, only a local one anchored in environment and competition. Over time, cumulative selection can produce the appearance of design, yet the process remains algorithmic and blind. Mayr invites us to trade ladder-of-progress metaphors for the dynamics of populations, where chance and necessity interact to generate the living world’s order and diversity.