Final answer:
Joe can imitate his sibling walking on a balance beam thanks to mirror neurons, which are specially adapted to facilitate observational learning and mimicking observed actions.
Step-by-step explanation:
After observing his sibling walk across a balance beam, Joe's brain reacts in a way that will enable him to imitate the action later mainly due to the functioning of mirror neurons. This specialized group of cells within the brain facilitates observational learning by activating both when an individual performs an action and when they observe someone else performing the same action, essentially mirroring the observed behavior internally.
These mirror neurons are thought to contribute significantly to the development of imitation skills, crucial for learning new motor tasks. Although neuroimaging studies have suggested that such a system exists in humans, invasive neurological studies like those done on primates are not performed on humans. However, there is substantial circumstantial evidence to support the role of mirror neurons in observational learning and possibly in the foundation for language in hominins.