The best time for youngsters to learn another language is in the first two to three years of life, according to Antonella Sorace, professor of developmental linguistics at Edinburgh University.
She believes that, while learning a second language later on is not a waste of time, leaving it until a child is in P6 is too late - especially if it is only for 30 minutes a week.
"The brain has the highest receptivity for language in early infancy and childhood," Professor Sorace said in a Royal Society of Arts lecture in Edinburgh. "Children can acquire languages spontaneously and without difficulty.
"Bilingual children have a number of cognitive advantages: they have greater sensitivity to language, they play with language and their parents report they are ferocious readers."
Sue Walters, a lecturer in educational studies at Moray House in Edinburgh, complained that the education system did not value bilingualism. "The main focus is on the benefits of developing English, not on the merits of bilingualism which is seen as a problem, not a resource," she said.
Yet, 106 different languages were spoken in Scottish schools.