  If, by contrast, language emerged independently in a number of areas, the existence of universals would be a strong argument for nativism,  For in that case, it would be implausible to maintain that each  ancestral group ‘just happened’ to select the same  solutions to the various coordination problems they encountered. More plausible would be the supposition that the different groups' choice  of the rule was driven by something internal to speakers,  such as, perhaps, an innate representation of UG. In short: if  languages have a common ancestor, then common descent from originally arbitrary linguistic conventions is a possible explanation of  linguistic universals, including the ‘odd’ or  ‘arbitrary’ ones that don't seem to have any real  functional significance. If they don't, then such universals  seemingly could only be explained in terms of features internal to  speakers.