Shout louder

THEN that cuckoo throw their eggs in the nests of other representatives of the feathered world, mostly quite small - well-known fact. And the fact that the adoptive parents of his hard feed, and much more abundant than chicks of their own - is not particularly sensitive information. But why such an embarrassment to befall nursing? Why are they hard to fatten him who then pushes the other kids out of the nest?
It turns out that the whole thing in a scream. Warbler nests in the study, which appeared cuckoo egg, it became clear that a foundling vociferous shouts so that the acoustic characteristics of its op like the cry of a warbler nest of chicks.
Decided to clarify this fact more extensively with other species of birds. All confirmed - a cuckoo cries for a clutch of medium size. And it concerns not only the volume but also TEMPO, and other voice characteristics.
However, it seems to me such examples can be found among the bipedal mammals, that is homo sapiens. Conservatively my observations, demanding screaming child still has a much better chance of getting the desired than modestly silent or timid whimper. With age, the methods are modified, but the essence remains. Requirest - once you get yes. Silent - so shut up.
So - cry and ask, gentlemen.