Is there a physiological reason to use pillows? I mean, could we physiologically not sleep (or would we suffer some worse fate) if we didn't use them?
I, for one, can't sleep without one, and I suspect most Dopers would say the same. But is that because of our anatomy, or is it because we've been sleeping with pillows since our moms first put them under our heads in the crib? In other words, we can't sleep without them because we're used to them.
Is there any culture that doesn't use pillows, thus proving that it's possible to get by without them?