Our understanding of when exactly adulthood starts is outdated according to new research.
While biological and social adulthood is seen to traditionally start at around 19, research published in Lancet Child & Adolescent Health says that changes in biology and society have combined to cause puberty to start earlier yet adulthood start later.
'Puberty' is biologically defined as when hormones are released which activate the pituitary and gonadal glands, triggering the noticeable bodily changes we usually associate with adults.
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 10.
However according to this paper, even as puberty is beginning earlier 'adulthood' is still coming later.
As lead author Professor Susan Sawyer writes: "Although many adult legal privileges start at age 18 years, the adoption of adult roles and responsibilities generally occurs later."
Since children are not marrying as young and remaining in the education system longer, they are not gaining full levels of independence as quickly and are instead remaining in a state of "semi dependency".
The researchers argue that law changes may be necessary, saying that we should consider anyone between the ages of 10-24 to be an 'adolescent' and offer them additional state support.
Though not all scientists agree with Professor Sawyer.
Dr Jan Macarvish, University of Kent Sociologist told the BBC the paper's suggestions may may further 'infantalise' young people and we should "continue to have the highest possible expectations of the next generation".