Humans have natural variation (for example, some people are introverted, some are extroverted, etc). The process of evolution "selects" certain "fitter" variants over others -- which is the same thing as saying that some people (with a specific set of gene variants) are able to survive longer than others, and so can pass on more of those gene variants to their children.
Thus, evolution is the process of converting knowledge about the environment (i.e. how to better "fit") into our physical form. The form of our genes, body and brain is the result of evolution, which is itself the action of selection of one form over another (against the environment) over time.
This turns the debate of nature vs. nurture on its head. We humans are the physical manifestation of millions of years of experience. Our form manifests an intimate knowledge of the environment, including knowledge of the other forms (people, animals, plants) around us.
Thus, the experience of mankind (over millions of years) creates our nature (the physical manifestation of experience), as our genes and form. Our form is designed to respond to the (expected) experiences in our lifetime, by bringing past experience (through the configuration of matter) to the present.