Roots of a social brain: developmental models of emerging animacy-detection mechanisms.

Here, we review evidence of unlearned predispositions to orient toward visual and auditory cues associated with the presence of animate creatures. We concentrate on studies on chicks of galliform species, whose behavioural preferences for social partners are analyzed in a comparative perspective with respect to the human developmental literature. The emerging nature of chicks' social predispositions is discussed in relation to the underlying physiological mechanisms and to the role of genetic and environmental factors in their development. In the second part of the review, we summarize evidence on the neural substrate of the animacy detectors, again focusing on our animal model of election, the domestic chick. On the basis of a substantial amount of indirect evidence, subpallial structures, among which the optic tectum (homologous to the mammalian superior colliculus), seem to comprise the most probable candidates. We also discuss some preliminary evidence of different brain activity, measured by IEG expression, in chicks exposed to predisposed or a non-predisposed stimulus.