  The literature on language evolution is too large to survey in this  article (but see Botha 2003 for an excellent overview and critique). Suffice it to note that as yet, no consensus has emerged as to how  innate knowledge of UG might have evolved from  whatever preadaptations existed in our ancestors. Of course, this is  not in itself a problem for linguistic nativists: formulating and  testing hypotheses about human cognitive evolution is a massively  difficult enterprise, due largely to the difficulty of finding  evidence bearing on one's hypothesis. (See Lewontin 1998 and Sterelny 2003:95-116.)