It's a case of nature and nurture. The human mind is geared towards
language and communication since we are "social" animals; however
frequent practice and reassertion of the association between physical
manifestations and semantics are required.
However, we can see examples of other "social" animals acquiring very
basic language skills, eg. koko the gorilla and sign language. The
reverse is also possible. If a child is kept in an environment where
they have no access to any "language" or communication, then beyond
that age of about 12/13 then they are unlikely to be able to fully
acquire language skills.
It has a lot to do with the way children learn. When a child initially
learns tenses, it is done through pure imitation. At this point, they
tend to get the tenses correct, even for irregular verbs.
However, through time, there is certain "insight" where they learn
that there are patterns/rules and they apply these to their speech and
in constructing simple sentences with past/future tenses and they are
able to correctly use past/future tenses of verbs previously unheard.
However, at this point their "hit rate" of correct tensing will
decrease dramatically, as they will also apply their newly learned
rules to all verbs including irregular verbs. By reinforcement of
which is correct/incorrect, then children will then learn that there
are irregular verbs to which these rules cannot be applied.
Here is a quote I found from the following webpage, "How do children
acquire language? Do parents teach their children to talk?"
"It's far easier for a child to acquire language as an infant and
toddler than it will be for the same child to learn, say, French in a
college classroom i8 years later. Many linguists now say that a
newborn's brain is already programmed to learn language, and in fact
that when a baby is born he or she already instinctively knows a lot
about language. This means that it's as natural for a human being to
talk as it is for a bird to sing or for a spider to spin a web. In
this sense, language may be like walking: The ability to walk is
genetic, and children develop the ability to walk whether or not
anybody tries to teach them to do so. In the same way, children
develop the ability to talk whether or not anybody tries to teach
them. For this reason, many linguists believe that language ability is
genetic. Researchers believe there may be a 'critical period' (lasting
roughly from infancy until puberty) during which language acquisition
is effortless. According to these researchers, changes occur in the
structure of the brain during puberty, and after that it is much
harder to learn a new language."
Here is an Excerpt from "The Language Instinct" by Steven Pinker, the
main reference book in this subject:
"All infants come into the world with linguistic skills. We know this
because of the ingenious experimental technique [...] in which a baby
is presented with one signal over and over to the point of boredom,
and then the signal is changed; if the baby perks up, he or she must
be able to tell the difference. Since ears don't move the way eyes do,
the psychologists Peter Eimas and Peter Jusczyk devised a different
way to see what a one-month-old finds interesting. They put a switch
inside a rubber nipple and hooked up the switch to a tape recorder, so
that when the baby sucked, the tape played. As the tape droned on
with "ba ba ba ba..." the infants showed their boredom by sucking more
slowly. but when the syllables changed to "pa pa pa..." the infants
began to suck more vigorously, to hear more syllables. Moreover, they
were using the sixth sense, speech perception, rather than just
hearing the syllables as raw sound."
A quote from "Is a child's learning ability set at a certain age?"
" We know that the first three years of life are extremely important
in a person's development. So much physical brain development is
happening during these years, as is the development of a child's sense
of herself as a capable learner. It is crucial that we as families and
members of society work to provide for children's critical needs
during these years.
However, because human beings are incredibly resourceful and
adaptable, it would be difficult to say that a person's capacity to
learn is fully determined by the age of three or even by the end of
childhood. While it may be much more difficult and costly to learn
certain things after the optimal stage has passed, with support and
effort, people have overcome early obstacles."
A quote from "Why, How, and When Should My Child Learn a Second Language?"
"Why Is It Better for My Child To Learn a Language in Elementary School?
Studies have shown -- and experience has supported -- that children
who learn a language before the onset of adolescence are much more
likely to have native-like pronunciation. A number of experts
attribute this proficiency to physiological changes that occur in the
maturing brain as a child enters puberty."
A quote from "Speaking From Within: A Discussion on Our Innate Ability
to Learn Languages":
"It turned out that language learning has a critical period. During
the acquisition of language, the brain goes through pruning of
unnecessary connections as language development takes place. In other
words, the neuronal synaptic connections are not created, or built as
we learn language: they pre-exist: unnecessary ones merely decay as
language learning takes place. As a result of this pruning period, the
ability to learn language fluently decreases with age. Young children
deprived of languages acquire language fully if learning takes place
before puberty. If after puberty, they are very inept at language.
Among Chinese and Korean children who have immigrated to the United
States there is a linear relationship until puberty between the age of
arrival and proficiency in English."
From Wikipedia on "Language aquisition":
"However, there exists emerging evidence of both innateness of
language and the "Critical Age Hypothesis" from the deaf population of
Nicaragua. Until approximately 1986, Nicaragua had neither education
nor a formalized sign language for the deaf. As Nicaraguans attempted
to rectify the situation, they discovered that children past a certain
age had difficulty learning any language. Additionally, the adults
observed that the younger children were using gestures unknown to them
to communicate with each other. They invited Judy Kegl, an American
linguist from MIT, to help unravel this mystery. Kegl discovered that
these children had developed their own, distinct, Nicaraguan Sign
Language with its own rules of "sign-phonology" and syntax. She also
discovered some 300 adults who, despite being raised in otherwise
healthy environments, had never acquired language, and turned out to
be incapable of learning language in any meaningful sense. While it
was possible to teach vocabulary, these individuals seem to be unable
to learn syntax.
The developmental period of most efficient language learning coincides
with the time of rapid post-natal brain growth and plasticity in both
humans and chimps. Prolonged post-natal brain growth in humans allows
for an extended period of the type of brain plasticity characteristic
of juvenile primates and an extended time window for language
learning. The neotenic pattern of human brain development is
associated with persistence of considerable language learning capacity
into human adulthood."
In summary: before puberty the brain is more adept at learning
languages. A child placed in an environment where they are exposed to
a language will eventually learn it with a certain ease. After a given
age, the brain changes and it is much more difficult to learn a
language with proficiency. Therefore, although some of the language
learning can be attributed to parents, most of it is due to genetic
factors and the external environment.
If you require any more clarifications or explanations, please do not
hesitate to ask.
The Language Instinct : How the Mind Creates Language (Perennial
Classics) by Steven Pinker
ability learn language children