On the ontogenetic origins of human smiling

To explore the meanings and the characteristics of early smiling, a series of studies in association with Miami and Utah University in the United States, and with Padova and Calabria University in Italy, have been conducted. The aim was to analyze the frequency and duration of the zygomaticus major activity in both full-term and pre-term neonates by using the Baby FACS (Oster, 2008), an anatomically based system used in identifying the muscular contractions responsible for changes in facial movement in infants and neonates. Previous studies were conducted prior to the development of anatomically based facial coding systems, which were prior to the introduction of improved technology (such as slow motion digital video) and also prior to the contemporary research distinguishing between different types of smiling. We will present four studies. Two studies which involved full-term neonates (Messinger, Dondi, Nelson-Goens, Beghi, Fogel, and Simion, 2002, N = 25; Dondi, Messinger, Colle, Tabasso, Simion, Dalla Barba, & Fogel, 2007, N = 32); and two studies that involved pre-term neonates (Dondi, Costabile, Rabissoni, Gianfranchi, Lombardi, & Corchia, 2004, N = 7; Dondi, Costabile, Vacca, Franchin, Agnoli, Lombardi, & Corchia, 2008, N = 9). Contrary to what has been generally reported in literature, we found that Duchenne smiling (smiles accompanied by raised cheeks, associated in adults as a positive emotion) is frequent in full-term and pre-term neonates, and that it was exhibited in all behavioural states examined. Unexpectedly, we also found a bilateral and unilateral frequent and brief motor activity of the zygomaticus major and an association between active (REM) sleep and long-lasting Duchenne smiles. The more general implications of these recent findings regarding the description of the developmental trajectory of human smiling will be taken into consideration.