[Paleopsych] NYT: With His Bells and Curves, Human Growth Science Grew Up

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With His Bells and Curves, Human Growth Science Grew Up
http://www.nytimes.com/2005/03/01/science/01tann.html
5.3.1

    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 -
    conclusion.

    "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
    normal, absolutely."

    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
    Olympic-caliber athlete.

    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
    growth."

    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.