At the cutting edge of evolution, changing conditions and competition leave few options: species and societies either evolve or die off. Evolutionary change results when either random mutation (in plants and animals) or conscious invention (in human societies) produces new structures with new capabilities.
The need for environmental relevance means that useful changes are preserved, while useless changes disappear. At each new biological and social stage new and more complex forms and functions emerge.
We are the products of many successful evolutionary transformations: inorganic evolution from subatomic particles to complex molecules; biological evolution from single-cell organisms to humans; social evolution from hunter-gatherer societies to industrial civilizations.