•Why it earns a slot
The most influential scientific challenge to the 'nature is pure competition' reading of Darwinism, written by a field naturalist whose own observations contradicted the theory he set out expecting to confirm.
Kropotkin, a naturalist and anarchist prince who spent years observing wildlife in Siberia, argues that Darwin's followers had badly narrowed the meaning of 'struggle for existence.' He claims cooperation within a species, not just competition against it, is a major and underappreciated driver of evolutionary success, and he builds the case from direct field observation rather than theory alone.
This distillation is written from the freely available original, which is always the better read when you have the time: Project Gutenberg.