Neonatal experiences and young development: what do studies on animal models reveal?
Résumé
The neonatal period in humans and in most mammals is characterized by intense mother-young interactions favoring pair bonding and adaptation of neonates to the extra-utero environment. Although postpartum handling (maternal separation, handling, assistance for first suckling…) is considered a routine procedure, the short- and long-term effects of such disturbances are still debated. Here, we chose the domestic horse as an animal model as like humans, they are characterized by single births, long lactating periods, selective mother-infant bonds and often undergo intense handling and maternal separation after birth. In a series of studies, we monitored the behavior of foals that underwent different neonatal experiences (bilateral or unilateral stimulations at birth, one single prolonged bout of handling at birth, a short assistance for first suckling) and that of control foals left undisturbed. The results showed : 1) that tactile stimulation at birth could have a different impact on emotivity according to the side of the stimulation; 2) that prolonged neonatal handling had short and long-term effects on mother-young attachment, social competences and emotional reactions; 3) that even a short and unique human interference had deleterious effects: when foals were forced to suckle instead of being allowed to suckle spontaneously, they not only had suckling difficulties, but also developed an insecure attachment to their mothers. We argue that both disturbances in the timing of mother-young interactions and preventing newborns from being actors of their own development may explain the deleterious effects neonatal interferences has on young development.