Scientific American Mind-June/July 2007

FAST FACTS
Innate Speech
1>>
In studies led by Jane A. Hurst at Oxford
Radcliffe Hospital in England, researchers found
that the affected members of the family, dubbed
the KEs, had a physically normal speech apparatus—lips,
jaw, tongue and vocal chords. Their
other fi ne-motor skills were normal, as were their
hearing and IQ. For three generations about half
the family members had suffered from the same
speech defect. Clearly, the disorder had a genetic
component and was specifi c enough in its effects
to offer the hope that it was directly connected to
that elusive speech gene.
When the gene responsible for the im pediment
was pinpointed just a few years later, it fi nally
provided evidence that the ability to speak is indeed
written in our DNA. But how exactly do
genes regulate a complicated mental process such
as speech? Studies of the gene in people and in
our animal cousins—especially songbirds, whose
vocal learning resembles that of people—could
help explain why speech evolved in humans but
not in any other species. They might also lead to
therapies for speech impediments like the one
plaguing the KE family.
Language in Our Genes
Geneticists led by Simon E. Fisher of the University
of Oxford identifi ed in the KE family a
segment on chromosome 7 in which there must
The discovery of the FOXP2 “speech gene” created a
sensation in the 1990s. Mutations in the gene lead to
specifi c linguistic and speech disorders.
2>>
FOXP2 is also part of the genetic makeup of monkeys,
songbirds and even crocodiles. Apparently it is not
solely responsible for human capacities but is only one factor
among many.
have been a mutation. But determining which of
the dozens of genes in that segment was at fault
promised to be a lengthy process of trial and error.
The researchers got a lucky break when they
found a boy from an unrelated family who had a
similar speech problem. The boy had a visible
defect on chromosome 7 in the same segment as
the one that looked suspicious in the KE family.
The chromosome was broken at a gene known as
FOXP2, so the researchers started looking spe-
( Some songbirds learn their songs in a way that is )
strikingly similar to how children learn speech.
3>>
There are striking similarities between human beings
and song-learning birds such as zebra fi nches. Both
acquire their “language” through imitation. Current work has
shown that birds need the FOXP2 protein for this purpose.
cifi cally at that gene. In 2001 they successfully
identifi ed FOXP2 mutations in KE family members
with the speech defect, and the same defect
was later confi rmed in other people with similar
speech impediments.
Ever since the fi rst published reports about
FOXP2, molecular geneticists and linguists have
been engaged in a vociferous debate about how,
precisely, the gene affects speech. Although the
gene appears to be crucial for normal development,
its specifi c role remains to be clarifi ed.
FOXP2 codes for a protein that affects hundreds
or perhaps even thousands of other genes, and
scientists have barely begun to understand its
complex infl uence. Mutations in the FOXP2
gene appear to hinder the development of brain
regions responsible for motor control as well as
regions involved in language processing. Furthermore,
the FOXP2 gene exists in a variety of species—from
reptiles to mammals—so it must serve
other functions besides facilitating speech.
Many researchers, including my team at the
Max Planck Institute for Molecular Genetics in
Berlin, are especially interested in FOXP2 in
birds, because some songbirds learn their songs
in a way that is strikingly similar to how children
learn speech. By studying the role of FOXP2 in
birdsong, we are revealing how it might affect the
development of language in people.
Genes ensure that the brain develops normally
in a number of ways. Specialized nerve cells
need to be formed, they need to produce the correct
connections to neighboring cells, and they
need to be able to emit signals or conduct messages
to other neurons. In addition, nerve cells in
the brain must develop the capacity to process
information so that they can “learn” things.
Gene products, namely, proteins into which the
68 SCIENTIFIC AMERICAN MIND June/July 2007
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