When do noticeable changes begin in human in adolescence?

Explanation

**Step-by-Step Solution:**

1. **Understanding Adolescence**: Adolescence is a developmental stage that marks the transition from childhood to adulthood. It typically involves various physical, emotional, and social changes.

2. **Identifying the Age of Onset**: Noticeable changes in humans during adolescence generally begin after the age of 11 years. This is the age when individuals start to experience the onset of puberty.

3. **Defining Puberty**: Puberty is the phase in which the body undergoes significant changes, leading to sexual maturity. It is characterized by the development of secondary sexual characteristics, growth spurts, and hormonal changes.

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