  The Ur-language hypothesis is not, of course, inconsistent with  linguistic nativism. However, if true, it does weaken any  argument from the existence of universals to the innateness  of linguistic knowledge. For if languages have a common ancestor,  then it is possible to explain universals — even ones that seem strange from a functional point of view — as being the result  of our ancestors' having adopted a certain solution to a linguistic  coordination problem. Like driving on the right side of the road, a  solution once established may become entrenched, because the benefits of everyone's conforming to the same rule outweigh the costs of  changing to a different rule, and this may be so even if the new rule were in some sense more ‘reasonable.’ Thus, even  arbitrary or odd features of language can be explained historically,  without positing either compelling functional considerations or  inborn linguistic   constraints.[18] 