To back their theory, researchers noted that education takes longer and young people are delaying marriage and moving out of their parents' house.
This used to happen around the age of 14 but improved diets and overall health in much of the developed world has seen puberty start to begin as young as ten.
The new age of adolescence is turning out to be 10 years to 24 years.
There are also biological factors to consider, including the fact that the brain and body both continue to develop after 18.
From a neuroscientific point of view, there may be some basis for extending the definition of this life stage, as research suggests that the cognitive development of the young can last until age 25. According to the Office of National Statistics (UK) in 2013 the average age for a man to enter first marriage was 32.5 in 2013 and the average age for women 30.6 years across England and Wales.
They argue that the brain is still maturing well beyond the age of 20 and wisdom teeth typically only come through around 25. In Britain, people are getting married almost eight years later than they were in 1973.
By changing the definition, we could potentially risk, "pathologizing their desire for independence", she said. Half of all females start experiencing puberty by 12 or 13 years of age.
The team says adolescence should be redefined for the good of the 1.8 billion people between ages 10 and 24 on the planet.
Adolescence is a period of vast change and growth-and young people are taking so much longer to mature that a team of doctors are now suggesting it be officially extended to age 24.
"Older children and young people are shaped far more significantly by society's expectations of them than by their intrinsic biological growth", she reasons.