[Paleopsych] NYT: With His Bells and Curves, Human Growth Science Grew Up
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Sun Apr 17 15:48:50 UTC 2005
With His Bells and Curves, Human Growth Science Grew Up
By STEPHEN S. HALL
DUNKESWELL, England - Dr. Jim Tanner pored over two children's growth
charts spread out on the table before him, observing the annual dots,
casting an expert eye on where they landed amid the centiles and
curves, lingering over the meager data about the 8-year-old girl, but
venturing a tentative - and, to her father, namely me, an unnerving -
"We're already seeing that she is going into early adolescence," Dr.
Tanner mused, peering over his glasses. "Eight and a half, hmmm. Well,
probably, probably, it's the beginning. That would be slightly early,
but for a takeoff for a girl nowadays? I mean, a bit early. But
We were sitting in a 100-year-old coach house that had once been part
of the Stentwood estate in Devonshire, two hours southwest of London
by train, and 15 miles farther, by curving one-lane roads, hemmed in
by encroaching hedgerows, from the train station in Taunton, the
nearest big town.
It may seem like a long way to go to ask a doctor to look at a child's
growth chart, especially when the doctor has been retired for 20
years. But Dr. James M. Tanner, even in retirement, remains one of the
greatest experts on a subject everyone experiences but few think
about, human growth.
Over a career that spanned half a century, Dr. Tanner helped bring the
study of human growth into the era of modern biology. He helped create
the first modern growth chart, has demonstrated the surprisingly
powerful influence of environment upon the average size of national
populations, and was among the first to argue that physical stature
can shed enormous light on the quality of life of cultures both modern
and ancient, findings that have revolutionized the field of economic
history. On top of that, he is that rarest of academic creatures: a
serious scientist who can legitimately claim to have been an
Although Dr. Tanner is largely unknown to the American public (with
the exception of pediatricians familiar with the so-called "Tanner
stages" of pubertal development), he is well known to his peers. Dr.
David Barker, the British epidemiologist who has studied birth weight
and early development, says flatly, "Jim is the god" of the field.
Dr. Robert Fogel, the Nobel Prize-winning University of Chicago
economist whose research on the lives and health of American slaves
was influenced by Dr. Tanner's work, said, "He's been one of the
central figures in the biology of human growth, and the books he's
written have become the central textbooks in the study of human
Now 84, Dr. Tanner still discusses growth, the role of nurture versus
nature in achieving maximum height, and a subtle - but, he believes,
important - approach to data collection that explains differences
between the growth charts that Dr. Tanner and his colleagues pioneered
in the 1960's and the charts now in use in the United States.
Sophisticated modern statistical approaches to childhood growth, in
the form of national growth charts, did not emerge until after World
War II. The first government-issued national charts in the United
States were released only in 1977 by the National Center for Health
Statistics. The Centers for Disease Control and Prevention updated
those charts in 2000.
Dr. Tanner and his colleagues at the Institute for Child Health in
London revolutionized growth charts in the 1960's by taking into
account variations in a child's tempo of growth. Rather than
one-size-fits-all curves, the Tanner-derived charts have separate
curves, with a separate set of percentiles, for early-, average- and
late-maturing boys and girls. Thus they expand the range of normal
growth, using curves that are more forgiving of individual variation,
especially around the crucial time of puberty.
"At 8, she's dead on the 50th centile," he said of my daughter's
growth data, "and what will happen now, dependent on when she has her
growth spurt, she'll either go up like this" - his finger tracing an
imaginary curve toward one adult height, "or she'll go up like that.
But she will not go like that," he added, touching on the dark 50th
centile curve on the chart.
"I think the deep, fundamental point in all this," Dr. Tanner
continued, "is differences in the rate of maturation. A child is small
at a certain age. Is he small because he's small and he's going to be
small unless he does something about it? Because another child, of the
same height and the same age and the same smallness, is just delayed
in his maturation. Perfectly normal. And will end up exactly average."
These subtle differences derive from the kind of data used to create a
growth chart. The American charts (and some modern European charts)
primarily rely on cross-sectional data: researchers take a large group
of children, separate them by age, measure them one time and then plot
the distribution of heights and weights for each age group.
In contrast, Dr. Tanner and others believe a more accurate (and
flexible) picture of a child's growth emerges from so-called
longitudinal studies, where the same children are repeatedly measured
over the course of many years of growth, so that individual variations
in tempo - those who mature early and those who mature late - can be
statistically incorporated into the charts. The data for such charts
are more logistically difficult and costly to collect. But some growth
experts believe such charts provide a more realistic picture of
variation in individual growth patterns.
To make the point, Dr. Tanner fetched one of his charts. There were
three different curves representing variations on normality. One, in
red, showed the trajectory of an early-maturing girl. The second, in
black, showed the trajectory of girls maturing "on time." The third,
in green, showed the trajectory of late-maturing.
"So you see, at age 2 they're pretty much the same," Dr. Tanner said,
pointing out a common starting point for three starkly different
growth trajectories. "But you get a very big effect later on."
At 11 years old, the 50th centile late maturer is nearly seven inches
shorter than the early maturer, he said. "But," he added, "a few years
later, they're identical."
"There are more ways of being normal than are shown here," Dr. Tanner
said, nodding toward the American-style charts. This philosophical
difference has always been controversial, although other experts agree
with Dr. Tanner, to a point. "He's absolutely right" about the
limitations of cross-sectional charts, said Dr. Alan D. Rogol, a
growth expert in Charlottesville, Va.
"You mush things together when you make a growth curve for a
population," Dr. Rogol said. "But for clinical work, I think the
differences are not all that great. It's a tempest in a teapot."
The Tanner-inspired longitudinal charts are still sold and used in
England, but he said their use had been overshadowed by
cross-sectional charts distributed by drug companies or growth
foundations that receive financing from companies that make human
growth hormone, the use of which has exploded in recent years.
Asked if cross-sectional charts made the use of growth hormone more
likely, Dr. Tanner said it would "if you're simple-minded."
"You're going to treat late maturers, lots and lots," he said.
Born in 1920, Jim Tanner grew up partly in Egypt and China; his father
was a career army officer. He attended St. Mary's School of Medicine
in London on something like an athletic scholarship, having agreed to
teach his fellow students physical education. He was the fastest
junior British runner in the 110-meter hurdles in 1939, and trained
with Britain's pre-Olympics track team. In all likelihood, he would
have competed in the 1940 Olympics, had it not been for the war.
He was among a handful of British medical students brought to the
United States by the Rockefeller Foundation to complete their studies.
He received his medical degree from the University of Pennsylvania,
did his internship at Johns Hopkins and met his first wife, Dr.
Bernice Alture, a Brooklyn-born general practitioner who also
graduated from Penn. (She died in 1991.)
The origins of the modern longitudinal growth chart began in 1948,
when Dr. Tanner was approached by the British government and asked to
take over a study of childhood growth that began during the war. The
study, focused on orphans living in a home in Harpenden, north of
London, was initially intended to observe the effects of wartime
malnutrition on growth. But it evolved into the Harpenden Growth
Study, the earliest of the longitudinal studies in postwar Europe.
To develop the methodology of what would become the first modern
growth chart, Dr. Tanner traveled to the United States and met with
growth experts. In his research, he realized that several prominent
American growth experts - including Dr. Franz Boas, the legendary
physical anthropologist, and Dr. Nancy Bayley, the psychologist at the
University of California, Berkeley - had understood the crucial
importance of tempo of growth. But Dr. Tanner also discovered that
their work had been largely ignored by their colleagues.
"We built this thing up, having just paid attention to what Boas and
Bayley were teaching us," Dr. Tanner recalled. He continued to work on
the Harpenden survey with his longtime associate, Reginald Whitehouse,
until 1971. Once a month, the two researchers traveled to Harpenden,
measured the children and took pictures, and later expanded the
research to include data from other European surveys. Their first
chart came out in the early 1960's.
In the same era, he was responsible for choosing the five or six
children in Britain who qualified for injections of human growth
hormone, then rare and harvested only from human cadavers. In 1985,
when several patients in the United States and Britain died from an
infectious brain disease spread through cadaveric growth hormone,
injections were immediately suspended.
Still, some families objected. "Some parents, amazingly, said, 'We'll
take the risk.' " Dr. Tanner recalled.
"We didn't accede," he added.
Treatments resumed only when genetically engineered human growth
hormone became available the next year. In the 1990's, Dr. Tanner set
out to write a new overview of growth, but soon abandoned the project.
"I realized that the time had passed when a single person could write
a textbook on growth," he said. "It just is not possible."
So his semi-retirement became permanent. "I would not consider myself
an expert anymore," he said.
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