The Father-Daughter Connection

Maybe father really does know best—or at least has a great deal of influence. According to a recent study by Penn State faculty, chemical cues from dads may be delaying the onset of sexual maturity in their daughters as part of an evolutionary strategy to prevent inbreeding.

"Biological fathers send out inhibitory chemical signals to their daughters," states lead research author Robert Matchock, assistant professor of Psychology at Penn State Altoona. "In the absence of these signals, girls tend to sexually mature earlier."

The effect of chemical cues on sexual maturity is common in the animal world, Matchock explains. For example, if the biological father is removed from rodent families, the daughters tend to mature faster.

The survey-based study, published in a recent issue of the American Journal of Human Biology, suggests that fathers may send out inhibitory chemical cues that delay their daughters' puberty by three months, as compared with the physical maturation of girls in fatherless homes.

The biochemical signals, called pheromones, are naturally occurring molecules that are usually airborne and odorless. These pheromones are believed to influence physiological behaviors such as choosing a mate.

"Recently, experts elsewhere discovered a little-known pheromone receptor gene, linking the role of pheromones to menarche, or the first occurrence of menstruation," Matchock states.

The research involved collecting data from 1,938 female college students to explore the link between the girls' social environment and their sexual maturity. The data included information on factors such as the girls' family size, social environment, date of their first menstrual period, and how long their father had been absent.

"Our results indicate that girls without fathers matured approximately three months before girls whose fathers were present," Matchock states, adding that the data seems to suggest a relationship between length of the father's absence and age of menarche—the earlier the absence, the earlier the menarche.

Results from the study additionally suggest that the presence of half and step-brothers also was linked to earlier menarche. Girls living in an urban environment also had earlier menarche compared to girls in a rural environment, even when fathers were present for both groups.

Matchock speculates that urban environments provide greater opportunities to get away from parents' inhibitory pheromones, and also allow the girls to encounter attracting pheromones from unrelated members of the opposite sex.

"It is possible that a stimulating urban environment can negate suppressive cues from parents," he adds.