Maternal hormones vs personality

​Hormones and personality

We studied the association between female and male personality traits and the early hormone environment provided by the mothers, in a common bird model for personality studies, the great tit (Parus major). We collected data on parental personality traits and egg hormone levels from a wild population, as well as from captive birds were we mated them randomly in respect to personality. Finally, we also performed an experiment where birds that were selectively bred for fast-bold or slow-shy personalities were mated both with partners of the same selection line (i.e. fast-bold female with fast-bold male) or from the opposite line (i.e. fast-bold female with slow-shy male). We found that females of different personality types indeed had different androgen levels in their eggs. For the independent effect of social environment, ie. the male personality traits, the results were not so clear. Data from the selection lines suggested no effect but data from wild population and captive, random-mated birds suggested that male traits, and interestingly, the combination of male and female personality matter. This study highlights the complex origin of animal personalities, and suggests that the social context may play a role in shaping the early hormone environment, and thus offspring development and personalities.

Suvi Ruuskanen
Read article