The universal grammar in the human being evolves as language.
It might evolve as one or more languages.
Depending on the environment and resources available on environment, it can evolve as Kannada, Swahili, German, or anything else.
If the child is in an environment where two languages are spoken, it might learn both.
It is a general conception that
it is good if a child has an opportunity to learn only one language. It will be complicated if there are more languages.
But that is not the fact.
Between 18 to 36 months, the child can convert Universal Grammar into any number of languages.
Basically, the Universal Grammar is the main source of language evolution.
To support his statement, he says one more thing.
A child's brain has a device to convert this universal grammar to language.
He calls it Language Acquiring Device, LAD.
This LAD takes the external resources,
even if they are very sparse,
and a part of the unlimited possibilities of universal grammar
and tries to convert into one language.
He presented the philosophy required for this in 1986,
the philosophy of Principles and Parameters.
I am not explaining that here.
Just like there are lot of similarities between the languages of the world,
even the differences are not much.
They are bound by certain parameters.
You can make only a few types of changes.
LAD helps in setting these parameters.
You can notice another challenge when you use a language in this society.
For example, why do we make mistakes when we use a language?
There are two types of mistakes in languages.
The first one, is related to its formation.
If I say I came home tomorrow, the mistake is in its formation.
You can't say I came tomorrow.
You can say I came yesterday or I will come tomorrow.
It has a grammar and it has to comply with that. This kind of mistake.
There is another type of mistake.
I had breakfast with Donald Trump.
There is no mistake from the language formation perspective.
The incident might be untrue.
The event that I had my breakfast with Donald Trump might be a lie.
But this is not a wrong sentence. This is only a fictitious sentence.
Language gives an opportunity to lie through its formation.
There need not be an equivalence to the words I speak.
That is why I can talk about heaven and hell.
I can talk about my experiences in London even without visiting London.
Or, I can imagine what happened 200 years ago and talk about it.
Similar challenge appears when we talk in multiple languages.
Kannada thinkers, proponents of pure Kannada say that
They use mixed language.
They mix Tamil, Telugu, or English words while talking in Kannada.
That is why this is a mixed language.
And, mixed language should not be used.
In reality, what we call a mixed language is not a mixed language.
We have to observe it carefully.
When there are English words in a Kannada sentence
English and Kannada are not mixed.
The entire sentence is formed in Kannada.
It is governed by Kannada.
I might have mixed English words in some places instead of Kannada.
Why did use English?
There might be many reasons for that.
Now, I ask what is the time? Why did I use the word "time" in English?
There might be several reasons for that.
But the rule behind this sentence is of Kannada only.
So, if I use words of other languages when I am talking in Kannada and when I am using the Kannada rules for sentences
It will not be an improper sentence.
And, there will be social reasons to mix that way.
It can be a matter of prestige
or, it can be due the person with whom I am talking.
When I am talking formally,
I may not be in a position to use a word from Kannada dialect.
In its place, I might bring a word from another language.
I might use English words.
There might be social reasons for that. But we can't say it is incorrect usage.
As I said earlier, the world of concept formation in our brains will not make mistakes.
It will be as it is supposed to be.
During externalization,
if one knows different languages, and it s not mandatory to learn different languages,
for example, if a villager uses English words while talking, it does not mean he has learned English.
These words became part of their vocabulary.
For example, let us assume someone says, if you go "straight" and take a "left", you see a "tower".
The person who used these three words may not know English.
Or, that person may not know that these are English words.
Basically, one need not know both languages to speak like this.
This is a natural process.
a natural process when using the language.
We generally call it incorrect or adulterated language usage.
I believe it is not so.
But Chomsky says a very important fact in next few decades.
When we say that the ability of language exists in humans, it is not a communication medium as we understand.
When we generally talk about language, we say that the it is a tool to share our opinion with others.
"to express themselves"
In reality, the expression or externalization is the secondary job of a language.
Because, even when we are not doing anything, we are thinking of something.
What is the meaning of thinking?
How do we get our thoughts?
What is the form of these thoughts?
When we start researching these
we observe that humans form more sentences than what they speak or can speak.
So, we are using the language capability even when we are idle.
So, what are the features of that capability?
He called it conceptual formation,
or Language of Thought.
This Language of Thought need not come out as the language we externalize, as speech or writings.
It can come out as signs in speech-impaired people.
It can come out as a painting or song from someone else.
But resources for that will always be evolving in human brain.
"How did that happen?" 
This question haunted Chomsky.
In 2005, he wrote about this in the article "Three factors which control the language design"
One was UG.
Second one, LAD
Third one is not related to language.
And, that is concept formation.
Forming a concept with the help of experiences available in this world or obtained from this world, be it sensory experience, memories or anything else.
We should understand Chomsky's views on concept very carefully.
We generally believe that the word or concept we form in our minds has an equivalent in the outside world.
But in reality, it is not so.
For example, you are watching a TV screen.
You see a continuous flow of images there.
Some figures are formed in your mind.
But in reality, those figures are not in the TV screen.
TV screen only has a continuous flow of pixels and not an image.
The image is formed only in our minds.
I mean, our understanding that there is a real world equivalent or the language for the experience we had in our minds, is not completely correct.
For example, someone might ask there is a word called "House".
Isn't there a house in this world?
But the important question is, which house is that?
Or, say the word, "Head".
There is no equivalent for the number of meanings my mind can give to the word "head.
For example, is it a human head, animal head?
Or does it mean the "chief"?
Or, is it in the context of "knowledge"?
So, there need not be an equivalent for all the interpretations of the word "Head".
It need not exist.
It is an independent world.
The quantity of language capability was or is same in all human minds across the world.
