Embodied syntax : impossible languages and the irreducible difference between humans and machines

How can we establish an objective boundary between machines and human brains when it comes to language? Modern neuroscience has proved that the limits of variations among languages, i.e., the Boundaries of Babel, are not a cultural or arbitrary convention: rather, syntax is embodied, i.e., impossible languages are defined by the neurobiological architecture of the brain. At the same time, impossible languages do not seem to be characterizable for machines, providing us with a robust objective way to differentiate between machines and brains.