Chapter 3 biological foundations: genes, temperament, and more. Hormones, brain waves, dna, physical appearance, reflexes and unconditioned responses are all aspects of biology that underlie social behaviour. Baby sensory and perceptual systems are biologically prepared to be sensitive to social stimuli, e. g. human voices, faces, smells. This preparation is adaptive because it increases a caregiver s attention towards a child and ensures the babies well-being. How are babies prepared: from biological rhythms to social rhythms. Baby behaviour follows biological rhythms, that they learn to control and regulate. Acquiring biological regulatory skills over the first 3 months allows babies to interact with mothers in a synchronous way (by showing a predictable degree of responsiveness to each other s signals) Under normal developmental conditions, babies develop biological rhythms that help them deal with the time-based natural of social interaction: visual preparation for social interaction.