Testosterone and Its Effects

Introduction to Testosterone

• Testosterone is a steroid hormone primarily produced in the testes in males and in smaller amounts in the ovaries and adrenal glands in females.

• Plays critical roles in health and well-being as well as the prevention of osteoporosis.

• Associated with a variety of physical and psychological behaviors.

Overview of Testosterone Handling

• Mentioned product: DepoⓇ-Testosterone, which is a sterile solution of testosterone cypionate at a concentration of 200 mg/ml.

• Package included details: Lot number (928DM) and packaging of 10 ml vials suggested for controlled dosages.

Class Discussion Topics

• Questions to consider:

  • What are the common perceptions of testosterone?

  • What truths exist around these perceptions?

• These discussions help to set a framework for understanding testosterone in biological and social contexts.

Differential Roles of Testosterone and Estrogen

• Testosterone vs Estrogen:

  • Overview of Hormonal Differences: Body composition, physical abilities, etc.

  • Discussion on how predominant levels of these hormones can impact individuals differently across genders.

Nature vs Nurture - Influences on Development

• Research on finger asymmetry suggesting hormonal influence on physical traits:

  • Specifically, the fourth finger (ring finger) in males is often longer than their index finger, a pattern established within three months of conception.

Correlation of Digit Ratio with Testosterone

• Noted correlation between long fourth fingers and higher testosterone and sperm counts:

  • Indicates potential hormonal impacts on physical attributes and reproductive success.

Contextualizing Sexual Selection

• Differences in anatomies (e.g., male gorillas with larger canines):

  • Emphasizes the concept of sexual selection, where certain traits develop even at a cost to survival.

• Reference to Darwin:

  • Suggested that traits that do not assist in survival yet evolve under sexual selection pressures can have dual significance in reproductive strategies.

Darwin’s Sexual Selection Theory

• Major tenets of Darwin's theory include the costs of sexual dimorphism:

  • Male sexual dimorphism, though costly, is inherited and features the handicap principle.

  • Behavioral costs influencing mating dynamics, highlighting a competitive nature within sexual selection.

Implications of Testosterone in Human Relationships

• Mating and parenting behavior:

  • Testosterone’s dual role in facilitating competitive behavior and parental care, leading to hormonal balance (i.e., ‘tightrope’) in humans.

• Mention of studies investigating testosterone in married versus single men.

Feedback Loop of Testosterone Production

• Diagram depicting the hypothalamic control of testosterone levels:

  • How GnRH from the hypothalamus stimulate the pituitary gland to secrete LH, leading to testosterone production in testes.

  • Illustration of negative feedback mechanisms involving inhibin and testosterone levels regulating reproductive health based on physiological state.

Testosterone and Cognitive Abilities

• Discussed relationship between testosterone levels and cognitive abilities in children:

  • Study conducted involving 78 boys and 69 girls aged 8 to 12.

  • Results indicated lower levels of salivary testosterone in intellectually gifted children.

• Mention of possible costs:

  • High testosterone may link with lower cognitive performance or higher aggression.

Testosterone Levels Linked to Criminality

• Research indicating correlations between salivary testosterone levels and criminal behavior findings based on self-reported actions versus the collection of biological data.

Link between Fatherhood and Testosterone Levels

• Recent studies suggesting that fatherhood is associated with decreases in testosterone, which allows for better child-rearing efforts:

  • Longitudinal studies have suggested this relationship might reflect a broader interaction between mating success and parenting duties due to hormonal shifts in fathers.

Gender Differences in Emotional Investment

• Mention of ongoing research regarding hormonal influences and emotional connections within same-sex relationships:

  • Areas of future research need to emphasize the complexity beyond traditional binary studies of hetero vs. homosexual interactions.

Conclusion on Testosterone and Its Impacts

• Summary of key findings:

  • Complex roles of testosterone across genders in behavior, physical attributes, emotional investment, and cognitive development.

  • Importance of context, social factors, and hormonal influences on human interactions and relationships.