The dark markings in the shark embryo pictured above indicate gene expression in the electro-sensory organs in the animal’s head. University of Florida researchers traced the origin of a shark’s electro-sensory powers to the same type of embryonic cell that gives rise to many head and facial features in humans.
Which means, the design of a human face, or any face for that matter, is rooted in the path of least resistance (or highest efficiency) as manifest by neural crest cells — the same cells that comprise the electricity-sensing organs in sharks that allow them to detect energy generated by prey.
Which means (assuming all vertibrates share a common ancestor), the vertibrate face is a tangible representation of millions of years of routing electric energy.
That said, check out this Wikipedia article on facial expression, including a picture from the 1862 book Mécansime de la Physionomie Humaine by Guillaume Duchenne, who used electric stimulation to determine which muscles were responsible for different expressions.