Early experience in domestication.

Two experiments using domestic and wild rats (Rattus norvegicus) were conducted to assess the ontogenetic as well as phylogenetic influences of early experience on domestication. Experiment 1 was a factorial, reciprocal cross-foster study. Experiment 2 was a factorial assessment of the combined effects of preweaning handling and postweaning enriched environments. These experiments on rat domesticatoin showed that preweaning handling has a strong influence on the ontogenetic development of the rat in terms of reduced emotionality. Handled wild rats became much more like domestic rats in their behavior. This finding for handling contrasted with minimal effects for cross fostering and enriched environments.