Adolescent Development week 2

Puberty

A biological transition marking the start of adolescence, driven by hormonal changes through activation of the hypothalamic–pituitary–gonadal (HPG) axis, which prompts the pituitary gland to release:

• Luteinising hormone (LH)

• Follicle-stimulating hormone (FSH) leading to sexual and reproductive maturity.

Initiation of puberty in females

Begins with activation of the hypothalamic–pituitary–gonadal (HPG) axis, which regulates hormonal signals leading to sexual maturation.

Gonadotropin-releasing hormone (GnRH)

A hormone released by the hypothalamus that stimulates the pituitary gland to secrete luteinising hormone (LH) and follicle-stimulating hormone (FSH).

Oestrogen

The primary female sex hormone produced by the ovaries, responsible for the development of reproductive organs, breast growth, and menstrual cycle regulation.

Primary sex characteristics

Changes directly related to reproductive function, such as the maturation of the uterus, ovaries, and onset of menarche.

Secondary sex characteristics

Observable physical changes not directly involved in reproduction, including breast development, pubic hair growth, and changes in body fat distribution.

Secular trend in pubertal timing

A historical decline in the average age of pubertal onset, especially menarche, due to improved nutrition and health, most evident in industrialised countries.

Thelarche and pubarche

refers to breast development, and the appearance of pubic and underarm hair—both are early signs of female puberty.

Tanner stages

A five-stage scale used to track the progression of physical sexual development in girls, based on breast and pubic hair growth.

Growth spurt

A rapid increase in height and weight during puberty, typically occurring earlier in girls and often peaking before menarche.

Menarche

The first menstrual period, usually occurring around ages 12–13, marking potential reproductive capability but not full reproductive maturity.

Spermarche

The first ejaculation containing viable sperm, usually occurring between ages 12 and 14, marking the onset of biological fertility.

Tanner stages in males

A five-stage scale used to track male physical development, including changes in genital size, scrotal skin, and pubic hair distribution.

Psychosocial stress

Early-life stressors such as conflict or father absence may accelerate puberty in girls through hormonal pathways, though extreme trauma can sometimes delay development.

Epigenetics

The study of how environmental factors can regulate gene expression without altering DNA, showing how experiences like stress can affect development.

Cultural responses to puberty

Puberty is often marked by rituals or ceremonies that symbolise the transition to adulthood, reinforcing cultural identity and social roles through practices such as instruction, seclusion, or symbolic trials.

Social perceptions of early maturation

Physical maturity may lead to being treated as older or more responsible, but can create tensions between appearance and emotional readiness.

Identity exploration and resilience

Puberty fosters psychological growth as adolescents engage with identity development and explore their social roles and future planning.

Growth spurt in males

A rapid increase in height and bone growth during puberty, typically occurring later in boys than in girls, around ages 13.5 to 14.5.

TIMING, PLASTICITY AND VULNERABILITY

• Ongoing neural plasticity

• Heightened emotional reactivity

• Increased independence

This creates both opportunities for growth and vulnerabilities, depending on the quality and consistency of their surroundings.

Genotype and Environment Effects

1. Passive gene–environment correlation

   • Parents pass on genes and shape environments.

   • E.g., A verbally skilled parent provides books and the genes for verbal ability.

2. Evocative gene–environment correlation

   • A child’s traits elicit reactions from others.

   • E.g., A cheerful child receives more positive attention.

3. Active gene–environment correlation (niche-picking)

   • Individuals choose environments that match their genetic tendencies.

   • E.g., A musically talented teen may join a band or enrol in music electives.

Genetics

Genetic factors strongly influence the timing of puberty, with specific genes (e.g., LIN28B, KISS1) regulating HPG axis activity and contributing to individual variation.

Diet and body fat

higher body fat and energy-dense diets are linked to earlier puberty, while undernutrition can delay development.

Psychosocial stress:

Early-life stressors such as conflict or father absence may accelerate puberty in girls through hormonal pathways, though extreme trauma can sometimes delay development.

Sleep

insufficient or irregular may contribute to earlier onset, possibly via hormonal disruptions

Physical activity

High levels of intense activity can delay puberty due to reduced fat stores, while low activity and sedentary behaviour are associated with earlier onset through increased body fat.

Aboriginal and Torres Strait Islander Contexts

puberty has traditionally been a time for:

• Spiritual growth

• Connection to kin and Country

• Preparation for adulthood

Benefits

• Identity development

• Resilience and emotional well-being

• Cultural connection and belonging

Aboriginal and Torres Strait Islander Gender Roles

• Boys may participate in initiation rites such as circumcision and receive teachings from male Elders about Lore, hunting, and responsibility

• Girls, upon menarche, may experience seclusion and be cared for by female relatives while learning about their roles as caregivers, cultural custodians, and knowledge holders

Family Relationships

Adolescents typically seek greater autonomy, prompting adjustments in:

• Household roles

• Privacy boundaries

• Rules around modesty and social activities

Supportive, communicative families can buffer the stress of puberty and help young people adjust more positively.