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Objective -To assess competing explanations for the universal preference of mothers to cradle infants on their left side and to propose a relation to hemispheric asymmetry for social attachment and communication behaviour. Methods -A review of observational, experimental, physiological, psychological, neuro-physiological, and neuro-psychological studies, including new findings on the cradling behaviour of mothers with auditory or visual impairments. Results -A significant leftcradling bias is observed in both right-and left-handed mothers which cannot adequately be explained by arguments based on handedness or closer contact to the soothing sound of the maternal heartbeat. Observations of primate behaviour have led to the suggestion that the left-cradling bias may be related to a left visual field (right hemisphere) advantage for monitoring an infant's facial expressions of distress. However, more than just monitoring, cradling subserves the mother's connection with the infant. For that reason, we have suggested that left cradling might be related to a right hemisphere specialisation for emotional communication, i.e. the speech melody, smiles, signals, and stroking which mothers use to interact with their infants. Studies of mother-infant interaction show that the sound of the mother's voice is more soothing when cradling on the left, more stimulating when cradling on the right. Cradling laterality may thus be related to emotional state and behavioural intent. There is also evidence to suggest that left cradling is linked to a special role of the right hemisphere in social attachment behaviour. This function may be disturbed in mothers with post-natal depression who show abnormal right hemisphere activity. Conclusion -Cradling embodies the symbiotic relationship between mother and infant; various lines of evidence support the suggestion that the universal preference of mothers to cradle infants on their left side is related to a right hemisphere dominance for social attachment and communication behaviour.

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I support the application of the "evolution as tinkering" idea to vocalization and emphasize that some of the subcortical parts of the brain circuits used for speech organs retain features common to nonprimate mammals, and in some cases to lower vertebrates, pointing up the importance of cortical evolution as suggested by MacNeilage. Abstract: This commentary supports MacNeilage's dismissal of an evolutionary development from sign language to spoken language but presents evidence of a feature in sign language (echo phonology) that links iconic signs to abstract vocal syllables. These data provide an insight into possible mechanism by which iconic manual gestures accompanied by vocalisation could have provided a route for the evolution of spoken language with its characteristically arbitrary form-meaning relationship.

Human studies consistently report a 60%-80% maternal left cradling preference. The dominant explanation points to an engagement of the emotionally more-attuned right brain. In contrast, we found equal incidences of left (31.3%), right (34.3%) and no-preference (34.3%) cradling in an impoverished South African population living under adverse conditions characterized by extreme dangers. We found striking differences on the Parenting Stress Index (PSI) between mothers with no cradling laterality preference and mothers with either a left or right preference. In several mammals a homologous left preference becomes stronger when acute threats prevail, rendering the rightwards shift we observed under dangerous conditions seemingly paradoxical. We propose this paradox can be resolved in terms of life-history strategy theory which predicts reduced parental investment in chronically dangerous environments. We interpret our high PSI score findings in no-preference cradlers as indicative of poorer, or at least ambivalent, maternal coping which many studies show is typically associated with reduced emotional sensitivity and responsiveness. We suggest that the latter may be a psychological mechanism mediating a partial withdrawal of parental investment in response to an enduringly adverse environment. To the best of our knowledge, this is the first study investigating cradling laterality preferences in an adverse socioeconomic environment.

An additional advantage of sign language for children with persisting receptive aphasia is that beyond supporting cognitive development and facilitating education, sign language also provides the child with access to a linguistic and social community. We would propose that recommendations regarding children with Landau-Klefmer syndrome should include in the first line the use of sign language, rather than nonlinguistic (gestural) or spoken language-dependent (reading, writing, sign systems) communication.

The families were taught to use the lancets and filter papers to complete the profiles. The first capillary blood spot was taken before 8 am, another around midday, one at 6 pm, and a final sample the next morning before 8 am. Those children on hydrocortisone supplements took the blood before their morning and evening doses of hydrocortisone. To examine reproducibility the profiles were repeated two weeks later. The children were asked not to take blood samples if they were unwell. All the profiles were completed at home and the filter papers posted to the laboratory and stored till processing in batches.The laboratory cost of a single four point profile in a batch of four profiles (, The quality of the blood spots was generally good with blood fully soaked through the filter paper to give two discs of greater than 6 mm diameter for each time point.Median rather than mean values were determined for both the 24 hour four point plasma