Since children learn languages as early as 18 months old, but can only learn from observing adults that do it the right way, they have no way of actively telling what’s right from wrong – they’re not studying languages, they just absorb them.

Yet they still apply the right rules at the right time. For example, even deaf children apply the correct grammar, just by learning sign language from their parents.

Children have a “window” for maximum language learning, while adults tend to have trouble learning a second language.

This window must exist because children around four years old learn grammar and vocabulary so quickly; this exponential learning cannot be explained by adult intervention or guidance. Language learning can be encouraged, and children must be in a social environment to absorb language, but the exact words they remember and the grammar they display probably has a biological basis.

All languages are based on the same two core principles.

How come we can talk so effortlessly to one another? What is it about language that makes it so easy to communicate with it? There are two forces at play here:

• The arbitrariness of the sign.
• Our infinite use of finite media.

The form words take doesn’t have a direct relation to their meaning.

For example the word “cat” doesn’t sound like a cat. The sound cats make is “meow” and they’re silent when they walk, whereas “cat” is a pretty strong, snappy, short and loud word.

This is a good thing, because it keeps us from trying to decipher what the word “cat” means by thinking about the way it sounds and instead lets us jump instantly to the result, because we’ve paired the word with the image through generations of rote learning instead.

This principle allows us to express anything and everything, because even though the number of words in any given language is limited, the number of combinations of words isn’t. Since we use the rules of grammar to create our own sentences, we’re not limited in how much we can express, which makes it easier to get your point across.

Grammar is a crucial part of language, and it pays to know it well. However, while you’d be punished horribly in school in the 1920s for bad grammar, today it’s not such a big deal, mainly because grammar rules are only one type of rules that determine how well you use language.

Grammar rules are prescriptive, which means they tell us how we’re supposed to talk or write. More and more though, scientists are concerned with descriptive rules, which describe how we actually talk.

You can be very much descriptively correct with your grammar, while being wrong in a prescriptive sense, just like a driver can follow the rules of physics in his car while breaking the laws of the country he’s driving in. Correct grammar is very much a relative thing, so don’t stress too much about it!

The theory that language is an instinct has opened up the possibility that humans have had access to language learning for about 2.5 million years.

There are specific genes and regions of the brain that develop to allow the individual to practice language.

While popular media accounts claim that chimpanzees can learn American Sign Language, most data suggest that chimpanzees are not mentally wired to acquire language. They lack the language instinct that humans possess.