Puberty is a complex period of growth and development that results in sexual maturity. The timing of puberty depends mainly on genetics but it can also be affected by environmental and behavioural things like nutrition, stress and chemical exposures.
Puberty usually starts between the ages of nine and 14 years old, and it normally lasts for five to six years. The timing of changes that occur during puberty is different from person to person.
What changes occur in males during puberty?
Usually, the first changes that occur during puberty in boys are an increase in the size of the testes and scrotum, followed by the penis. One testicle (or testis) might grow faster or a bit bigger than the other but this is normal. Around this time, pubic hair starts to grow but it becomes thicker and darker with time.
Then there’s a growth spurt, when height increases quicker than before, and the chest and shoulders get broader. During this stage, growth of the body is not always even. The hands, feet and head might grow before other parts of the body, and the legs might get longer more quickly than the torso. This disproportionate growth can cause problems with coordination, resulting in clumsiness or you can look a bit looking gangly. Males usually get 10-30 cm taller during puberty and stop growing at around 18-20 years.
Gynaecomastia (the growth of breast tissue) can occur during puberty but it usually goes away with time.
Other changes that occur during puberty include the growth of body and facial hair, which can continue to develop after puberty. The skin usually starts producing more sweat and oil during puberty, which can cause body odour and pimples. A male’s voice changes throughout puberty, as the larynx (part of the upper airway) gets larger.
As puberty progresses and the reproductive system matures, males have more frequent erections, sometimes without any stimulation. Erections during sleep are common, especially in rapid-eye-movement (REM) sleep. Ejaculation during sleep is also common, often but not always in association with dreams.
Throughout puberty there are changes to the structure and the function of the brain that result in changes in behaviour, emotion and thinking.
What causes the changes during puberty?
The changes that occur in boys’ bodies and minds during puberty are caused by increased production of testosterone by the testes after puberty begins but the exact thing that starts puberty is unknown.
What affects the timing of puberty?
Genetics has the biggest effect on the timing of puberty, with other factors having less of an effect. However, we know less about the influence of these other factors for boys than for girls because there are more studies of females than males.
Stress in early life appears to result in earlier puberty in boys, as it does in girls.
Nutrition in early life affects the timing of puberty in complicated ways. Children with low birthweights (which indicates a lack of nutrients before birth) have earlier puberty than normal birthweight children. Children who are overweight or who have obesity also have earlier puberty onset, whereas severe obesity seems to delay the start of puberty in boys.
Undernutrition, chronic diseases and excessive exercise can all cause a delay in puberty onset. Environmental pollution that exposes boys to chemicals that affect hormone levels may cause puberty to start earlier or later than normal. Social factors, like where someone lives or their socioeconomic status, can also affect the timing of puberty.
Does the timing of puberty matter?
Early puberty is associated with increased risk of obesity, type 2 diabetes, cardiovascular disease, behavioural and emotional problems, risk-taking, and reduced height.
In rare cases of abnormally early or delayed puberty, it may be necessary for a specialist medical practitioner to use hormone treatment to delay or start puberty. There are no other circumstances in which deliberately delaying or advancing puberty is necessary or safe.
If you have concerns about puberty you should talk to your doctor. They can help to manage problems that might arise during puberty (e.g. acne, changes in mood) and refer you to a specialist for treatment of a medical cause of a problem with the timing of puberty.
Tim Moss
Healthy Male Health Content Manager
Associate Professor Tim Moss has PhD in physiology and more than 20 years’ experience as a biomedical research scientist. Tim stepped away from his successful academic career at the end of 2019, to apply his skills in turning complicated scientific and medical knowledge into information that all people can use to improve their health and wellbeing. Tim has written for crikey.com and Scientific American’s Observations blog, which is far more interesting than his authorship of over 150 academic publications. He has studied science communication at the Alan Alda Centre for Communicating Science in New York, and at the Department of Biological Engineering Communication Lab at MIT in Boston.
