In what would seem to be a sudden, surprise counterattack by the Whorfian hypothesis, a tribe of otherwise smart people have been discovered whose language doesn’t have words for specific numbers, and where the people have major trouble with the idea of specific numbers of things (even when taught & when trying very hard). The children of the tribe can pick up numbers easily, but the adults don’t.
Constance Holden. Life Without Numbers in the Amazon. Science 2004; 305 (5687) : 1093a (in News of the Week)
More information is in this CNN article.