Looking at the human body, we can see that we certainly are unique among God's creation. In fact, there are a number of ways in which we are unique from the animal kingdom. We are fearfully and wonderfully made... Psalm 139.
Only man can walk completely upright - we were designed to do just that. God created Adam as a mature adult male, therefore, he walked uprightly. A baby's early motor development leads to many physical and mental achievements including walking uprightly. Examples of early developmental milestones include turning over by one's self, lifting up one's head, cross crawl on tummy, cross creep on hands and knees, "cruising" with the help of furniture, walking with hands above waist for balance, walk with a good cross swinging of both arms below the waist.
Further, we can speak in an abstract, symbolic language. We understand spoken language; we speak language; we read written language and we write language. Being able to read means that we have vision that enables this great feat. Learning to read can seem so easy for some that we do not realize its complexity until we spend some time with those that have great difficulty. As far as the vision is concerned the physical eyes must be intact and properly connected to the visual cortex. These two eyes must be able to track horizontally and vertically as well as work together. Further, one must be dominant and the subdominant must support the other. To understand spoken language the inner ear must be working properly without excessive fluid and to be properly connected to the temporal lobe of the brain. For writing to be possible, one must control the writing instrument sufficiently to form the characters. Of course we can talk about the physical act of writing as well as coming up with the ideas and how to get them on paper in a way that makes senses to others.
At least one other area should be mentioned - that of touch. Only mankind can identify an object by touch alone. Again, this requires communication between our sensory nerves and the brain. One can be hypersensitive or hyposensitive to tactile sensations. Either way, it disrupts the communication and affects one's life and learning. One of the main challenges of neurodevelopmentalists is understanding normal development and identifying missing pieces or steps in development. Only then can one teach parents different activities that will stimulate the brain in a way that will encourage development. What a blessing this is for the families.