Changes in Stereotypies: Effects over Time and over Generations

SIMPLE SUMMARY: Herein, we propose that there should be discussion about the function and effects of stereotypies in relation to the time during which they are shown. In the first stages, stereotypies may help animals deal with challenges. However, behavior can potentially alter the brain, impairing its function due the absence of a diverse repertory, and change brain connections, neurophysiology and later neuroanatomy. The neuroanatomical changes in individuals showing stereotypies could be an effect rather than a cause of the stereotypy. As a consequence, studies showing different outcomes for animal welfare from stereotypy expression could be due to variation in a timeline of expression. Stereotypies are widely used as an animal welfare indicator, and their expression can tell us about psychological states. However, there are questions about the longer-term consequences if animals express stereotypies: do the stereotypies help in coping? During the prenatal period, stereotypic behavior expressed by the mother can change the phenotype of the offspring, especially regarding emotionality, one mechanism acting via methylation in the limbic system in the brain. Are individuals that show stereotypies for shorter or longer periods all better adjusted, and hence have better welfare, or is the later welfare of some worse than that of individuals that do not show the behavior? ABSTRACT: Stereotypies comprise a wide range of repeated and apparently functionless behaviors that develop in individuals whose neural condition or environment results in poor welfare. While stereotypies are an indicator of poor welfare at the time of occurrence, they may have various consequences. Environmental enrichment modifies causal factors and reduces the occurrence of stereotypies, providing evidence that stereotypies are an indicator of poor welfare. However, stereotypy occurrence and consequences change over time. Furthermore, there are complex direct and epigenetic effects when mother mammals that are kept in negative conditions do or do not show stereotypies. It is proposed that, when trying to deal with challenging situations, stereotypies might initially help animals to cope. After further time in the conditions, the performance of the stereotypy may impair brain function and change brain connections, neurophysiology and eventually neuroanatomy. It is possible that reported neuroanatomical changes are an effect of the stereotypy rather than a cause.