Yamill was researching early maturation in girls. Some of the information that she gathered regarded early puberty in girls and girls who were abandoned by their fathers. What was the link between paternal abandonment and early puberty in girls that Yamill may have determined by her research?

The timing of human puberty is strongly linked to genetic and dietary factors. It is also linked to historical changes, and a secular trend favoring early menarche has resulted in an ever increasing proportion of teens attaining reproductive capacity at young ages. The causes of the trend, however, have not been unequivocally ascertained. More generally, we know very little about the factors in children's proximal environments that either inhibit or accelerate the timing of pubertal maturation. But, between 1984 and 1987, it has been distributed a survey with questionnaires to over 1,000 participants who were asked about their early family experiences and their physical development. The results from this retrospective study suggest that parental absence especially the absence of the biological father-is associated with early menarche.

your answer is "the 1950's"