All life descended from some unknown prototype Publishes The Origin of the Species in 1859 after receiving manuscript from Wallace Work of Alfred Russell Wallace was equally perceptive. Natural selection-what is it and why is it important. A. Summarized and dissected by Ernst Mayr into facts and inferences. Great potential fertility. Exponential population growth if all reproduced successfully and all offspring survived.
Resources are limited.
More individuals than environment can support leads to struggle for existence. Only a fraction of offspring survive. No two individuals are exactly alike. Even identical twins differ slightly, e.g., weight, etc. Much variation is inheritable.