Ok I understood the half truth
http://www.npr.org/templates/story/s...toryId=5716366
"The other cry in the newborn cryfolio, the basic cry, is used for everything else. It is most typically heard when the baby is hungry, which is why it is often called the hunger cry. It is the same cry the baby uses when his diaper is dirty or for any other nonemergency issue. The basic cry has a more gradual buildup and a lower pitch. It does not have the long periods of breath-holding or the frantic, emergency quality of the pain cry. That's why mothers hearing that cry will often say "Oh, she's just hungry," or "She just wants to be picked up." They are fairly nonchalant about it, and that's fine."