Some believe it's for visual function. I believe it could also help with balance. However, I don't believe anyone truly knows.
Visual control of head movements during avian locomotion. 255, May 1, 1975: 67-69. The optokinetic basis of head-bobbing in the pigeon.
Journal of experimental biology, v. Danbury, CT, Grolier, c2004. And behaviour of the pigeon.
London, New York, Academic Press, c1983. R.W. The first steps in seeing.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.