What type of learning shapes innate behaviors?

Innate behavior is very often considered to be th eresult and a consequence of learning which was done in the earliest stages of life; womb, infancy up to childhood possibly. Most of the time, this learning has to either be model learning of reinforcement learning where the organism or child, if we're talking about human beings, get feedback once they do something; either negative - diminishes the behavior, or positive - increases it. 

Fossil found in strata reveal that unused body part decrease in size