"Rather than age 10-19 years, a definition of 10-24 years corresponds more closely to adolescent growth and popular understandings of this life phase and would facilitate extended investments across a broader range of settings", said study lead author Susan M Sawyer from the Centre for Adolescent Health at the Royal Children's Hospital in Melbourne.
Given that young people are now spending more time in school and are waiting longer to do things like get married and start a family the time when adulthood officially begins is getting pushed back, the BBC reports.
Puberty is considered to set in when the hypothalamus starts releasing a hormone that triggers a body's pituitary and gonadal glands.
The average age of the onset of puberty has been steadily dropping in the developed world for decades, due to improvements in health and nutrition. For example, the brain continues to mature beyond the age of 20, working faster and more efficiently.
As a result, the average age for a girl's first menstruation has become younger by four years in industrialized countries like the U.K.in the past 150 years.
"My experience of young people is that they still need quite a considerable amount of support and help beyond that age".
The past century has seen drastic changes in the definition of adolescence, which encompasses elements of biological growth and major social role transitions.
Sawyer further stated that although age definitions are always arbitrary but our current definition of adolescence is too restrictive.
"The ages of 10-24 years are a better fit with the development of adolescents nowadays", she said.
Adolescence now lasts until the age of 24, scientists have claimed.
Prof Russell Viner, president-elect of the Royal College of Paediatrics & Child Health, said: "In the United Kingdom, the average age for leaving home is now around 25 years for both men and women".
Some academics contest the Lancet piece, including sociologist Jan Macvarish from the University of Kent, who tweeted that "science really can't tell us how to live our lives and raise our children and what adulthood means".
We should not risk "pathologising their desire for independence". Do you feel like an adolescent?
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