Should a child acquire a language within 12 years of its birth?

Question

One of the professors of linguistics told us (resource persons) that if a child does not live with humans and acquire at least one language within twelve years of its birth, then the child will never acquire any language later. Is the professor right or is there any flaw in his sayings?

My question is:

Should a child be exposed to language twelve years of its birth to learn one or more languages?

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Resourse persons are those selected by the government for training teachers of English in the state.

Answer 1

The wikipedia article on feral children, that is children who have been raised by animals, might be useful: https://en.wikipedia.org/wiki/Feral_child

It claims:

They often seem mentally impaired and have almost insurmountable trouble learning a human language.

The reference, however, is not to published scientific literature, but rather to a popular science website without further references to credible literature: https://www.zmescience.com/other/feature-post/feral-children/

The wikipedia page also states that there is little published science on the matter. Controlled experiments are obviously non-ethical and abandoned children tend to suffer from a variety of problems, which makes it difficult to isolate what is the cause of any deficiency in language.

However, I found the article

GRIMSHAW, Gina M., et al. First-language acquisition in adolescence: Evidence for a critical period for verbal language development. Brain and Language, 1998, 63.2: 237-255.

which discusses the case of a deaf person without contact to the deaf community, who was then fitted with a learning aid and started learning Spanish.

Quote from the discussion:

We have presented here a case of linguistic isolation in the context of normal cognitive and emotional development. E.M.’s case is consistent with the hypothesis that there is a critical period for first-language acquisition that ends at puberty, if not before.

For further information, I suggest reading the article; you can find a freely available PDF via Google scholar: https://scholar.google.dk/scholar?cluster=5578210677808468823 . For further information, try finding relevant articles that cite that one, e.g. via Scholar https://scholar.google.dk/scholar?cites=5578210677808468823 , and the relevant articles cited in the article itself.

You might also be interested in the critical period hypothesis in general: What are the main arguments for and against the critical period hypothesis, and what are alternative explanations?