If two human babies were placed on an island isolated with no one to?
This is one of the oldest questions around. And according to one of the oldest authors around, it was resolved by experiment 2650 years ago. Lets hand over to Herodotus, writing in 440BC about the Egyptian Pharoah we now call Psamtik I (664610BC): Now before Psammetichus became king of Egypt, the Egyptians believed that they were the oldest people on earth. But ever since Psammetichus became king and wished to find out which people were the oldest, they have believed that the Phrygians were older than they, and they than everybody else. Psammetichus, when he was in no way able to learn by inquiry which people had first come into being, devised a plan by which he took two newborn children of the common people and gave them to a shepherd to bring up among his flocks. He gave instructions that no one was to speak a word in their hearing; they were to stay by themselves in a lonely hut, and in due time the shepherd was to bring goats and give the children their milk and do everything else necessary. Psammetichus did this, and gave these instructions, because he wanted to hear what speech would first come from the children, when they were past the age of indistinct babbling. And he had his wish; for one day, when the shepherd had done as he was told for two years, both children ran to him stretching out their hands and calling Bekos! as he opened the door and entered. When he first heard this, he kept quiet about it; but when, coming often and paying careful attention, he kept hearing this same word, he told his master at last and brought the children into the king's presence as required. Psammetichus then heard them himself, and asked to what language the word Bekos belonged; he found it to be a Phrygian word, signifying bread. Reasoning from this, the Egyptians acknowledged that the Phrygians were older than they. This is the story which I heard from the priests of Hephaestus' temple at Memphis; the Greeks say among many foolish things that Psammetichus had the children reared by women whose tongues he had cut out. (Herodotus, Histories, Book 2) Well, they didnt have ethics boards then. There are other reports of similar historical experiments, with the language developed being reported variously as Hebrew or a basic sort of sign language. But theres nothing that I know of that goes much beyond legend. We do have many well-documented instances of slaves being brought together in groups with no common language. Invariably, some form of creole languages soon develop, where words from the mother tongues of the various groups are combined with original, invented ones. Given this, it doesnt seem far-fetched to suggest that two healthy children would come up with some way of communicating, and that this would probably be vocal in nature, but its not at all clear why youd call this any more or less natural than any other human language.