The meaning of the gesture is clear whether it’s with one upturned palm, the “Brother, can you spare a dime” stance of beggars around the world, or with the two-palm version favored by preachers who reach out to beseech divine assistance. Or by exasperated Hollywood directors who rise from their chairs with upturned palms to implore their actors, “Work with me, people!”
The upraised palm is the automatic accompaniment to an apology or an alibi. As you try blaming the computer for eating your homework, you shrug your shoulders and expose your palms as a show of helplessness. What could I do? How could I know?
Primatologists claim that gestures and speech evolved simultaneously into language. And that the upturned palm is
one of the oldest and most widely understood signals in the world. It’s
activated by neural circuits inherited from ancient reptiles that
abased themselves before larger animals. Chimps and other apes, notably
humans, adapted it to ask not just for food, but also for more abstract
forms of help, creating a new kind of signal that some researchers
believe was the origin of human language.
The whole story is at A World of Eloquence in an Upturned Palm – New York Times