The fundamental distinction between animals and all living beings is movement. Animals emerged out of living beings becoming able to make distinctions in their surroundings, give meaning to those distinctions, and move towards or away from what they sensed based on those meanings. The ability to move, sense the surroundings (dominantly visual/olfactory/tactile cues), and process the sensory stimuli (cognition) c0-evolved. For example, the hemoglobin of the retina is genetically identical to the hemoglobin of muscle tissue. (Science June 14, 2013). In animals, there is nothing more fundamental than movement.
Our post-industrial culture has been quite successful at minimizing movement. The ramifications of our success are expressed cognitively, emotionally, and biomechanically, influencing every aspect of our lives and well-being. The Katy Bowman interview below is an excellent overview of some of the consequences of this lifestyle, and her efforts to live innately in the modern context.
Here is an excellent NPR report on movement and play: