Inductivist

A new study from Hormones and Behavior:

The testes are active during gestation, as well as during early infancy. Testosterone elevation during fetal development has been shown to play a role in human neurobehavioral sexual differentiation. The role of early postnatal gonadal activation in human psychosexual development is largely unknown, however. We measured testosterone in 48 full term infants (22 boys, 26 girls) by monthly urinary sampling from day 7 postnatal to age 6 months, and related the area under the curve (AUC) for testosterone during the first 6 months postnatal to subsequent sex-typed behavior, at the age of 14 months, using the Pre-School Activities Inventory (PSAI), and playroom observation of toy choices. In boys, testosterone AUC correlated significantly with PSAI scores (Spearman's rho = 0.54, p = 0.04). In addition, play with a train and with a baby doll showed the anticipated sex differences, and play with the train correlated significantly and positively with testosterone AUC in girls (Spearman's rho = 0.43, p = 0.05), while play with the doll correlated significantly and negatively with testosterone AUC in boys (Spearman's rho = − 0.48, p < 0.03). These results may support a role for testosterone during early infancy in human neurobehavioral sexual differentiation.

A new study from Homones and Behavior reveals a black-white difference among children in cortisol levels throughout the day. A flatter diurnal slope is associated with more chronic stress and health problems.

As shown in the graph, whites wake up with a significantly higher level which then falls more quickly throughout the day. The different slope remains even when the following factors are controlled: age, gender, non-steroid medication usage, sleep, wake time, socioeconomic risk, psychosocial risk, perceived discrimination, harsh parenting, and parental monitoring.

Compared to blacks, the slope for Hispanics is more similar to whites, although Hispanics do have lower cortisol levels than whites by evening time.

The authors suggest that since morning levels of cortisol are known to be influenced by genes, the racial difference might be due, in part, to genetic differences.