18 AUGUST 2002: THE LANGUAGE
GENE?

From the 15
August New York Times:

Language Gene Is Traced to
Emergence of Humans

By NICHOLAS WADE

A study of the genomes of
people and chimpanzees has yielded a deep insight into

the origin of language,
one of the most distinctive human attributes and a

critical step in human evolution.

The analysis indicates that
language, on the evolutionary time scale, is a very

recent development, having
evolved only in the last 100,000 years or so.

The finding supports a novel
theory advanced by Dr. Richard Klein, an

archaeologist at Stanford
University, who argues that the emergence of

behaviorally modern humans
about 50,000 years ago was set off by a major genetic

change, most probably the
acquisition of language.

The new study, by Dr. Svante
Paabo and colleagues at the Max Planck Institute

for Evolutionary Anthropology
in Leipzig, Germany, is based on last year’s

discovery of the first human
gene involved specifically in language.

The gene came to light through
studies of a large London family, well known to

linguists, 14 of whose 29
members are incapable of articulate speech but are

otherwise mostly normal.
A team of molecular biologists led by Dr. Anthony P.

Monaco of the University
of Oxford last year identified the gene that was

causing the family’s problems.
Known as FOXP2, the gene is known to switch on

other genes during the development
of the brain, but its presumed role in

setting up the neural circuitry
of language is not understood.

Dr. Paabo’s team has studied
the evolutionary history of the FOXP2 gene by

decoding the sequence of
DNA letters in the versions of the gene possessed by

mice, chimpanzees and other
primates, and people.

In a report being published
online today by the journal Nature, Dr. Paabo says

the FOXP2 gene has remained
largely unaltered during the evolution of mammals,

but suddenly changed in
humans after the hominid line had split off from the

chimpanzee line of descent.

The changes in the human
gene affect the structure of the protein it specifies

at two sites, Dr. Paabo’s
team reports. One of them slightly alters the

protein’s shape; the other
gives it a new role in the signaling circuitry of

human cells.

The changes indicate that
the gene has been under strong evolutionary pressure

in humans. Also, the human
form of the gene, with its two changes, seems to have

become universal in the
human population, suggesting that it conferred some

overwhelming benefit.

Dr. Paabo contends that humans
must already have possessed some rudimentary form

of language before the FOXP2
gene gained its two mutations. By conferring the

ability for rapid articulation,
the improved gene may have swept through the

population, providing the
finishing touch to the acquisition of language.

“Maybe this gene provided
the last perfection of language, making it totally

modern,” Dr. Paabo said.

The affected members of the
London family in which the defective version of

FOXP2 was discovered do
possess a form of language. Their principal defect seems

to lie in a lack of fine
control over the muscles of the throat and mouth,

needed for rapid speech.
But in tests they find written answers as hard as

verbal ones, suggesting
that the defective gene causes conceptual problems as

well as ones of muscular
control.

The human genome is constantly
accumulating DNA changes through random mutation,

though they seldom affect
the actual structure of genes. When a new gene sweeps

through the population,
the genome’s background diversity at that point is much

reduced for a time, since
everyone possesses the same stretch of DNA that came

with the new gene. By measuring
this reduced diversity and other features of a

must-have gene, Dr. Paabo
has estimated the age of the human version of FOXP2 as

being less than 120,000
years.

Dr. Paabo says this date
fits with the theory advanced by Dr. Klein to account

for the sudden appearance
of novel behaviors 50,000 years ago, including art,

ornamentation and long distance
trade. Human remains from this period are

physically indistinguishable
from those of 100,000 years ago, leading Dr. Klein

to propose that some genetically
based cognitive change must have prompted the

new behaviors. The only
change of sufficient magnitude, in his view, is

acquisition of language.