In humans, the right hand is dominant worldwide, with a smaller percentage of people being left handed or using both. However, society can alter this i.e. in the King's Speech, Colin Firth's character was born left-handed but made to use his right or something like that. This dominant hand is due to brain organisation and in one of Stout's papers, the overlap of language and motor areas are mentioned which can be especially seen in the babkin reflex of newborns, and when people use their hands when talking. So, even in places where writing systems are directed from right to left, there still should be a larger population of right-handers. A nice little article on this is http://www.scientificamerican.com/article.cfm?id=why-are-more-people-right