A demographic shift appears to have taken place in the realm of scientific and medical breakthroughs.
A new study of Nobel laureates from 1901 to 2008 looks at how old scientists were when they made their major discoveries.
Before 1905, about two-thirds of the winners did their groundbreaking work before the age of 40, and about 20 per cent did it before age 30.
But by the turn of the century -- the year 2000 -- almost none of the great achievements occurred before the age of 30.
The study, which appeared online Monday in the Proceedings of the National Academy of Sciences, finds that in physics, great achievements by age 40 only occurred in 19 per cent of cases and almost never occurred by age 40 in the field of chemistry.
Researchers from Northwestern University and Ohio State University say the age shift likely has to do with the types of breakthroughs honoured by the Nobel prize, as well as the length of time it takes for scientists to receive training and begin their careers nowadays.
Altogether the study looked at 525 Nobel Prizes in three fields: 182 in physics, 153 in chemistry and 190 in medicine.
"The image of the brilliant young scientist who makes critical breakthroughs in science is increasingly outdated, at least in these three disciplines," co-author Bruce Weinberg, professor of economics at Ohio State University, said in a statement.
"Today, the average age at which physicists do their Nobel Prize-winning work is 48. Very little breakthrough work is done by physicists under 30."
He said the results could be seen as good news for science today in light of the aging of the workforce.
If someone takes the view that science is a young person's game, then the aging trend is alarming, he said.
"But if scientists can be productive as they get older, as this study suggests, there may be less of a problem," he said.
