Courtesy of your friendly neighbourhood rng, this week’s great idea in linguistics is… language acquisition! Or, in other words, the process of learning  a language. (In this case, learning your first language when you’re a little baby, also known as L1 acquisition; second-language learning, or L2 acquisition, is a whole nother bag of rocks.) Which begs the question: why don’t we just call it language learning and call it a day? Well, unlike learning to play baseball, turn out a perfect soufflé or kick out killer DPS, learning a language seems to operate under a different set of rules. Babies don’t benefit from direct language instruction and it may actually hurt them.

In other words:

Language acquisition is process unique to humans that allows us to learn our first language without directly being taught it.

Which doesn’t sound so ground-breaking… until you realize that that means that language use is utterly unique among human behaviours. Oh sure, we learn other things without being directly taught them, even relatively complex behaviours like swallowing and balancing. But unlike speaking, these aren’t usually under concious control and when they are it’s usually because something’s gone wrong. Plus, as I’ve discussed before, we have the ability to be infinitely creative with language. You can learn to make a soufflé without knowing what happens when you combine the ingredients in every possible combination, but knowing a language means that you know rules that allow you to produce all possible utterances in that language.

So how does it work? Obviously, we don’t have all the answers yet, and there’s a lot of research going on on how children actually learn language. But we do know what it generally tends to look like, precluding things like language impairment or isolation.

1. Vocal play. The kid’s figured out that they have a mouth capable of making noise (or hands capable of making shapes and movements) and are practising it. Back in the day, people used to say that infants would make all the sounds of all the world’s languages during this stage. Subsequent research, however, suggests that even this early children are beginning to reflect the speech patterns of people around them.
2. Babbling. Kids will start out with very small segments of language, then repeat the same little chunk over and over again (canonical babbling), and then they’ll start to combine them in new ways (variegated babbling). In hearing babies, this tends to be syllables, hence the stereotypical “mamamama”. In Deaf babies it tends to be repeated hand motions.
3. One word stage. By about 13 months, most children will have begun to produce isolated words. The intended content is often more than just the word itself, however. A child shouting “Dog!” at this point could mean “Give me my stuffed dog” or “I want to go see the neighbour’s terrier” or “I want a lion-shaped animal cracker” (since at this point kids are still figuring out just how many four-legged animals actually are dogs). These types of sentences-in-a-word are known as holophrases.
4. Two word stage. By two years, most kids will have moved on to two-word phrases, combining words in way that shows that they’re already starting to get the hang of their language’s syntax. Morphology is still pretty shaky, however: you’re not going to see a lot of tense markers or verbal agreement.
5. Sentences. At this point, usually around age four, people outside the family can generally understand the child. They’re producing complex sentences and have gotten down most, if not all, of the sounds in their language.

These general stages of acquisition are very robust. Regardless of the language, modality or even age of acquisition we still see these general stages. (Although older learners may never completely acquire a language due to, among other things, reduced neuroplasticity.) And the fact they do seem to be universal is yet more evidence that language acquisition is a unique process that deserves its own field of study.