The development of the human brain is a very complex process characterized by a multitude of developmental changes in behaviour. Developmental changes are specific during the prenatal period and in the first two years of a child's life, given that the maturation of the central nervous system is still very intense during this period. Typical motor development is characterized by variation and the development of adaptive variability, while atypical development is characterized by limitations in variation and variability. Although there are several developmental theories, Neuronal Group Selection Theory represents a balance between the previous Neuromaturationial Theories and Dynamic Systems Theory, therefore it dictates that development is the result of a complex interweaving of information from genes and the environment. Development begins with primary selection neural repertoires, and continues based on afferent information that produces behavior and experience. Secondary neuronal repertoires and their associated selection mechanisms form the basis of mature variable behavior that can adapt to environmental constraints. Neuronal Group Selection Theory is used as a theoretical reference framework for the qualitative assessment of motor behavior of infants under the name Infant Motor Profile, precisely because of the fact that variations and adaptability of motor behavior are key elements of typical development. Infant Motor Profile assesses the motor behavior of infants aged 3 to 18 months divided into 5 domains: variation, adaptability, symmetry, fluency, and performance. This form of assessment has proven to be a reliable and valid instrument for the assessment of neuromotor status in infants and enables the early detection of developmental motor disorders. The aim of the paper is to present knowledge about the variation and adaptability of motor behavior and to include an overview of existing research on the predictive power of the mentioned domains of motor behavior for neurodevelopmental outcome. The paper will define the theory of neuron selection, the concepts of primary and secondary variability, and elaborate on the importance of the qualitative domain of motor behavior in infancy.