“Man has an instinctive tendency
to speak, as we see in the babble
of our young children,” wrote
Charles Darwin1in 1871, “while no child has
an instinctive tendency to bake, brew, or
write.” Darwin’s observation has just been
supported in a way he could not have dreamed
of, with the discovery by Lai and colleagues2
(page 519 of this issue) of a gene that is mut-
ated in a disorder of speech and language.
The possibility that human language abil-
ity has genetic roots was raised about forty
years ago by the linguist Noam Chomsky3and
the neurologist Eric Lenneberg4. Chomsky
noted that language is universal, complex
and rapidly acquired by children without
explicit instruction. Lenneberg pointed out
that a small number of children fail to display
this talent and that such deficits sometimes
run in families. Deficits of this kind are
now called ‘specific language impairment’,
an umbrella term for language disorders that
cannot be attributed to retardation, autism,
deafness or other general causes. Specific
language impairment not only runs in fami-
lies but is more concordant in identical than
in fraternal twins, suggesting that it has a heri-
table component5. But the inheritance pat-
terns are usually complex, and until recently
little could be said about its genetic basis.
Then, in 1990, investigators described the
‘KEs’ — a large family, of several generations,
in which half the members suffer from a
speech and language disorder6. This disorder
is distributed within the family in a manner
that suggests it is caused by a dominant gene,
or a set of linked genes, on an autosomal
(non-sex) chromosome. The press referred
to it as a ‘grammar gene’ (Fig. 1), while scep-
tics suggested that it merely lowers intelli-
gence or makes speech unintelligible, or
even that the disorder is nothing more than
an artefact of a working-class dialect.
Extensive testing by psycholinguists,
including Faraneh Vargha-Khadem, one of
the authors of the paper in this issue2,
suggested that the disorder is more complex
than either of these extremes7,8. Affected
family members do tend to score below
average in intelligence tests (perhaps because
verbal coding helps performance in a variety
of tasks). But the language impairment can-
not be a simple consequence of low intelli-
gence, because some of the affected members
score in the normal range, and some score
more highly than their unaffected relatives.
And although the affected members have
problems in articulating speech sounds
(especially as children) and in controlled
movements of the mouth and tongue (such
as sticking out their tongue, or blowing on
command), their language disorder cannot
be reduced to a problem with motor control.
They also have trouble identifying basic
speech sounds, understanding sentences,
judging grammaticality, and other language
skills. For example, as adults they stumble
at a task involving nonsense words that most
four-year-olds pass with ease: completing
sequences such as ‘Every day I plam; yester-
day I _____’9.
In 1998 several of the authors of today’s
paper linked the disorder to a small segment
of chromosome 7, which they labelled
SPCH1 (ref. 10). Now, thanks to the discov-
ery of an unrelated person known as CS, who
has both a similar speech deficit to the KEs
and a chromosomal translocation affecting
the SPCH1 segment, Lai et al.1have nar-
rowed the disorder down to a specific gene,
FOXP2. In CS, this gene is disrupted by the
translocation. In all the affected members
of the KE family examined, but in none of
the unaffected members, and in none of 364
chromosomes from unrelated, unaffected
people, a single guanine nucleotide is
replaced by an adenine. (The perfect contin-
gency is in striking contrast to the now-you-
see-it, now-you-don’t correlations found in
the first generation of searches for genes
affected in behavioural disorders.) The
authors propose that the nucleotide replace-
ment results in substitution of the amino
acid histidine for an arginine in one struc-
ture — the ‘forkhead’ domain — in the
gene’s protein product, presumably altering
the protein’s function.
Lai et al. present hints that FOXP2 may
have a causal role in the development of the
normal brain circuitry that underlies lan-
guage and speech, rather than merely dis-
rupting that circuitry when mutated. FOXP2
belongs to a family of genes that encode
transcription factors (proteins that trigger
the copying of genes into messenger RNAs),
many of which have important roles in
embryonic development. One of the defin-
ing features of proteins in this family is the
forkhead domain, which contacts a target
region in DNA, and it is this domain that is
affected by the mutation in FOXP2. FOXP2
appears to be strongly expressed in fetal
brain tissue (among other places), and its
homologue is expressed in the developing
cerebral cortex of mouse embryos. In both CS
and the affected members of the KE family,
only one copy of FOXP2 is disrupted. So Lai
et al. suggest that, at a critical point in fetal
brain development, affected individuals
have only half the normal amount of func-
tioning transcription factor, which is not
enough to control some aspect of early brain
development.
Whatever the exact function of the gene
turns out to be, the new work2has many
implications. As a smoking gun for a genetic
cause of one kind of language disorder, the
discovery motivates the search for genetic
causes of cognitive and learning disorders
more generally, relieving the presumption
of guilt from mothers (who are often still
blamed for everything that goes wrong
with their children). It also shows that just
because a cognitive disorder has a genetic
cause, it is not necessarily untreatable. The
affected KE adults learned to compensate
for their difficulty in generating complex
linguistic forms by memorizing the forms
NATURE
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VOL 413
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4 OCTOBER 2001
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www.nature.com 465
news and views
Talk of genetics and vice versa
Steven Pinker
Figure 1 Genes and speech: a cartoonist’s view of
a ‘language gene’. The identity of a gene affecting
speech and language has been pinned down by
Lai et al.2, writing in this issue. (Reprinted with
special permission, North America Syndicate.)
Does our ability to talk lie in our genes? The suspicion is bolstered by the
discovery of a gene that might affect how the brain circuitry needed for
speech and language develops.
© 2001 Macmillan Magazines Ltd
