4.1 ADULTS 85 In Iran, women become adults at 9 and men at 15. In other countries such as Cuba, Palestine, Scotland, Uzbekistan, the age of majority occurs at 16; in some states of Canada and the USA, Algeria, and South Korea at 19; in Japan, New Zealand, and Taiwan at 20; in Cameroon, Chad, Madagascar, Nicaragua, and Honduras, children become adults at 21. How do you feel about getting older? PHYSICAL CHANGES Definition of adulthood According to Erikson s theory of psychosocial development, adulthood can be divided into early adulthood (20-40) and middle adulthood (41-65 years), which correspond to stages 6 and 7 of life. Although most countries have a legally defined age to determine when a person is considered an adult, i.e. the age of majority, and although adulthood has traditionally been defined by a combination of age and the achievement of social milestones such as leaving the family, getting a job, getting married, or having children, around the world, the idea of adulthood when it starts, and how it is defined is being challenged since there are many variations in attitudes and behaviours regarding it. After age 30 People tend to lose lean tissue: muscles, liver, kidneys, and other organs may lose some of their cells. This process of muscle loss is called atrophy and happens for different reasons, including lower levels of muscle-building hormones and changes to muscle fibres. People typically lose about 1 cm every 10 years after age 40. This tendency to become shorter as one ages occurs among all races and both sexes and is related to ageing changes in the bones, muscles, and joints. Skin ageing normally begins around the age of 25, when the body progressively reduces producing collagen, causing the skin to lose elasticity. This causes the formation of wrinkles and, later, age spots on the skin. Greying often begins and men may start showing signs of baldness. baldness: calvizie gain: aumento lean: magro milestone: pietra miliare stamina: resistenza steady: costante stiff: rigido swiftness: prontezza wrinkle: ruga Physical signals Whatever the age adulthood starts, some physical signals help to identify it. Physical changes in early adulthood include reaching full height and weight, muscle gain, and a slight increase in body fat. Early adults also peak in physiological functioning as they experience increased muscle strength, reaction time, agility, bone density, and cardiac functioning. 176 ADULTS AND ELDERLY PEOPLE Most people start experiencing a decline in their energy levels by the time they reach their mid-thirties. This steady decline starts around age 30 and speeds up after hitting 60, but, although we cannot expect to be able to stop the human ageing process completely, there are different ways to slow down the process and keep oneself healthy. Getting enough sleep, protecting skin with sunscreen, eating a balanced diet, exercising, and managing stress can slow biological ageing.