Final answer:
Secondary curves in the human back develop gradually after birth as the child learns to sit upright, stand, and walk. These curves include the cervical curve in the neck region and the lumbar curve in the lower back.
Step-by-step explanation:
Secondary curves in the human back develop gradually after birth as the child learns to sit upright, stand, and walk. These curves are concave posteriorly and are opposite in direction to the primary or fetal curve. The secondary curves include the cervical curve in the neck region and the lumbar curve in the lower back.