Final answer:
Babies cannot immediately crawl or focus their eyes due to the gradual maturation of their nervous system and the need for muscle coordination development post-birth. Myelination continues post-birth and motor skills develop in an orderly sequence, with milestones reached over time through practice and growth.
Step-by-step explanation:
While human babies' muscles and neurons are developed at birth, they cannot focus their eyes, sit up, or crawl immediately due to several factors that influence their neuromotor development. Motor skills development follows an orderly sequence, where infants first manage simpler movements and reflexes before advancing to more complex motor skills. The process of myelination, crucial for efficient nerve impulse transmission, is not fully complete until adolescence, indicating that the newborn's nervous system is still maturing post-birth.
Furthermore, infants need to develop muscle coordination and strength, despite having functional muscles at birth. For example, newborn reflexes are present, such as sucking and rooting, which are inborn, automatic responses. These reflexive actions are critical for survival but are distinct from voluntary control over movements required for crawling or sitting up.
Baby milestones, such as sitting or head control, have an average age range when they are typically achieved. This development involves gradual strengthening and coordination, which develop over time through practice and growth.
Newborn senses like hearing and internal vision are relatively well-developed at birth, yet other senses, including depth perception and visual focus, take time to mature. Muscle development is continuous, stimulated by the fetus's movements, but full control over these muscles is not immediate upon birth.