The first reading is our primary one.   Look at the second quickly.

Also review our primer on kin selection

Maynard Smith, J.   1991.   Honest signalling: the Philip Sidney game.   Animal Behaviour 42:   1034-1035. [.pdf]

Johnstone, R. A.   1999.   Signaling of need, sibling competition, and the cost of honesty.   Proceedings of the National Academy of Science USA 96:   12644-12649.