[Skuu]

When you have scientific studies like this, the way they're summarised and reported by a medic outlet isn't necessarily the main thing they were about. Scientists tend to do specific research on topics that haven't been thoroughly understood. This area of linguistics is such a topic.

So you may hear something on the news and say, 'huh? didn't we already know that?' but you may only think that due to vague/incomplete previous research that was touted as a new fact by the way it was reported.

I'm not entirely sure what people are calling old; the ease of language learning with prepubescents was known and probably wasn't the focus of the study. This was more likely the ease of learning using the 'lessons' for older children.

Also remember that in science, v. rarely does a single study prove a theory, even if it is well controlled and produces very strong results. Although it does depend on the presumed probability of the mechanism behind the result being true, e.g. it's quite likely that even older children can still learn another language relatively easy, but this isn't proven. So a single, strong study could nearly prove this.