Database results:
examBoard: Pearson Edexcel
examType: IGCSE
lessonTitle: Secondary Sexual Characteristics
During puberty, our bodies go through dramatic changes that transform us from children into adults capable of reproduction. These changes are known as secondary sexual characteristics - physical features that distinguish males from females but aren't directly involved in reproduction themselves.
Key Definitions:
Secondary sexual characteristics evolved as signals of reproductive fitness. Many of these features help potential mates identify healthy, mature individuals who would make good reproductive partners. This is why they develop during puberty - they're biological signals that say "I'm ready to reproduce!"
The development of secondary sexual characteristics is controlled by hormones - chemical messengers that coordinate changes throughout the body. During puberty, the brain's pituitary gland sends signals to the testes or ovaries to start producing sex hormones.
In boys, the main sex hormone is testosterone, produced by the testes. Testosterone triggers the development of male secondary sexual characteristics. The pituitary gland releases hormones called gonadotrophins that stimulate the testes to produce testosterone.
In girls, the main sex hormones are oestrogen and progesterone, produced by the ovaries. Oestrogen is primarily responsible for female secondary sexual characteristics. The pituitary gland releases gonadotrophins that stimulate the ovaries to produce these hormones.
During puberty, boys undergo several physical changes triggered by testosterone. These changes prepare the male body for its reproductive role and typically occur between ages 10-17, though timing varies between individuals.
The larynx (voice box) enlarges and vocal cords lengthen, causing the voice to "break" and become deeper. This is often called "voice breaking" and may happen gradually or suddenly.
Boys typically experience a significant increase in height and muscle mass. Shoulders broaden and the body develops a more angular shape with less body fat.
Hair grows in the pubic area, under arms, on the face (beard and moustache) and sometimes on the chest, back and other parts of the body.
Other important changes include:
Girls also undergo significant changes during puberty, typically between ages 8-16, though this varies between individuals. These changes are primarily triggered by oestrogen.
The menstrual cycle begins, with periods occurring approximately monthly. This indicates that the ovaries have begun releasing eggs (ovulation).
Breast tissue develops and enlarges, often being one of the first signs of puberty in girls. This prepares the body for potential future breastfeeding.
The pelvis widens and fat is deposited around the hips, buttocks and thighs, creating a more curved body shape with a narrower waist.
Other important changes include:
Research shows that the average age of puberty onset has decreased over the past century. In the 1800s, girls typically began puberty around age 16-17. Today, the average age is 10-11. Scientists believe this may be due to improved nutrition, decreased physical activity and exposure to certain environmental chemicals. This trend has important implications for physical and psychological development, as children may be developing adult bodies before they're emotionally mature.
While secondary sexual characteristics aren't directly involved in reproduction, they serve important biological and social functions:
Many secondary sexual characteristics prepare the body for reproductive roles. For example, wider hips in females create a birth canal suitable for childbirth. Increased muscle mass in males historically helped with protection and resource gathering. Some characteristics, like facial hair, may have evolved as signals of reproductive maturity and health.
Secondary sexual characteristics help us identify potential mates. They also play a role in social interactions and identity formation. Throughout history, many cultures have celebrated the development of these characteristics with coming-of-age rituals that mark the transition to adulthood.
Puberty doesn't happen overnight - it's a process that takes several years. While the timing varies between individuals, the sequence of changes tends to follow a pattern:
The timing and pace of puberty vary widely between individuals. Early or late development is often perfectly normal and may be influenced by genetics, nutrition, overall health and environmental factors. However, extremely early (precocious puberty) or late (delayed puberty) development may require medical attention.
The development of secondary sexual characteristics involves a complex hormonal pathway:
This system works through negative feedback - when hormone levels get too high, they signal the hypothalamus and pituitary to reduce production, maintaining balance in the body.
Secondary sexual characteristics are the physical features that develop during puberty and distinguish males from females without being directly involved in reproduction. They're controlled by hormones - primarily testosterone in males and oestrogen in females. These characteristics include voice changes and facial hair in males and breast development and menstruation in females, among many others. The timing and sequence of these changes vary between individuals but typically follow predictable patterns. Understanding these changes helps us appreciate the complex biological processes that transform children into reproductively capable adults.
Log in to track your progress and mark lessons as complete!
Login NowDon't have an account? Sign up here.