"Looking at almost 6,000 children's books published between 1900 and 2000, the study, led by Janice McCabe, a professor of sociology at Florida State University, found that males are central characters in 57% of children's books published each year, with just 31% having female central characters. Male animals are central characters in 23% of books per year, the study found, while female animals star in only 7.5%."