Fernando Alonso believes there is no one rule fits all and that Max Verstappen, even at 17, could be ready for Formula 1.
The Dutch racer, who is just 16 at the moment, will make his debut next season having signed with Toro Rosso.
Verstappen, who will be 17 when he races at the season-opening Australian GP, will be the youngest driver ever to compete in Formula 1.
It has raised questions about whether he is too young, however, Alonso says he should be judged on his ability and not his age.
"I think it is just one number on your passport the age," he told Sky Sports News HQ.
"At the end of the day you need to be ready for the challenge and be ready for Formula 1 grands prix.
"Some people are ready at 17, some people are ready at 28 - that is what we don't know.
"So before saying anything we need to see how Verstappen does next year and after six to eight races we can see if he was ready or not.
"But at the moment anyone is ready."