Linguistics knows of about 10000 languages. Each has a unique grammar, which native speakers more or less learn by age 5. Now, say Baker, Chomsky and other Chomskian linguists, each language has too many peculiar grammatical features that set it apart from other languages; it would have made more sense if there were Boolean "parameters": when a child learns the value of a parameter, he knows several grammatical features at once. English is a head-first language; in English, a verb usually comes before its direct object ("bit the man" in "The dog bit the man"), before a phrase that starts with a preposition ("ran to the doghouse" in "The dog ran to the doghouse"), and before a that-clause ("said that the dog bit him" in "The man said that the dog bit him"). Japanese is a head-final language; in Japanese a verb usually comes after all three. Also, in English a preposition comes before its noun phrase, and in Japanese a postposition comes after its; in English a noun usually comes before a prepositional phrase, a complementizer ("if", "whether", etc.) before its clause, and an auxiliary verb before its main verb; in Japanese it is the opposite. Presumably, a child can easily find out, whether its native language is like Japanese or like English, and learn all seven features at once. Baker has studied Mohawk, an Iroquoian language spoken in Quebec, Ontario and Upstate New York, which is polysynthetic: a verb can combine with its object into a single word, similarly to currying in functional programming languages (like the English "to baby-sit", but much more productively). Baker says that whether or not a language is polysynthetic is even more important than whether it is head-first or head-final, and if it is, then several things are true about its grammar at once, and if it isn't, then they are all false at once. Well, an expert on Basque reviewed the book; he says that all these things are true about Mohawk and false about English, but only some are true about Basque, and others are false. Baker himself mentions Amharic, a language related to head-first Semitic languages but surrounded by head-final Cushitic languages, where verbs come after their direct objects but there are prepositions instead of postpositions. He says that such languages are rare. I can't propose anything better, but the practice of counting languages with or without some grammatical feature looks suspect to me. Japan (sans the Ryukyu Islands) has had political unity since the times of Amaterasu, so there is only one Japanese language (as opposed to Okinawan and other Ryukyuan languages). In contrast, Italy was politically disunited from the 5th till the 19th century CE, so there are approximately 15 Romance languages native to Italy. If you match Japanese with Venetian, Sicilian, Piedmontese etc., will it reveal some profound fact about human nature, or artifacts of political history of the last two millennia?