This is a very good question. It seems quite possible that some human population at some point, may have endured a level of stress and adverse conditions, that

This is a very good question. It seems quite possible that some human population at some point, may have endured a level of stress and adverse conditions, that proper language transfer to the children did not happen -- something like a mix of surviving adults from different cultures who do not speak the same language. There are apparent examples of languages being invented, with no clear parent language. [1] When education for the deaf is first introduced, children from many different families are brought together. Most do not have full language - they cannot communicate with language with anyone. Some are part of small clusters, families or small villages where many are deaf. [2] They often do have full languages. These languages are usually untraceable in origin. They're not related to each other, usually. Pool these kids these together in a school and they will create a full language, a creole [3], in just a few years. It's unclear, IMO, exactly how to interpret that effect. The children are not completely without language. They're obviously aware of the concept of language, a few of them may even have full languages (even if they can't use it with the other kids) and the teachers are also trying to teach them language, usually American sign if there's nothing local. So it can't be said to be language popping up in a true vacuum. But it is certainly curious. [1] https://en.wikipedia.org/wiki/Nicaraguan_Sign_Language https://en.wikipedia.org/wiki/Nicaraguan_Sign_Language [2] https://en.wikipedia.org/wiki/Martha%27s_Vineyard_Sign_Language https://en.wikipedia.org/wiki/Martha%27s_Vineyard_Sign_Langu... [3] https://en.wikipedia.org/wiki/Creole_language https://en.wikipedia.org/wiki/Creole_language