[Paleopsych] NS: Teenagers special

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Teenagers special: The original rebels
      * 05 March 2005
      * Lynn Dicks
      * Lynn Dicks is a writer based near Cambridge, UK

    EAST Africa, one-and-a-half million years ago: a group of women sit
    with their young children. They are heavy-browed with small skulls -
    not quite human, but almost. Some are checking their children for
    ticks, others teaching them how to dig tubers out of the ground. Not
    far off, a gaggle of teenage girls lounge under a tree, sniggering and
    pointing at some young men who are staging fights nearby. The older
    women beckon: "Come and help us dig out this root - it will make a
    great meal," they seem to say. But the girls reply with grunts and
    slouch off, sulkily.

    Could this really have happened? Our immediate ancestors, Homo
    erectus, may not have had large brains, high culture or even language,
    but could they have boasted the original teenage rebels? That question
    has been hotly contested in the past few years, with some
    anthropologists claiming to have found evidence of an adolescent phase
    in fossil hominids, and others seeing signs of a more ape-like pattern
    of development, with no adolescent growth spurt at all. This is not
    merely an academic debate. Humans today are the only animals on Earth
    to have a teenage phase, yet we have very little idea why.
    Establishing exactly when adolescence first evolved and finding out
    what sorts of changes in our bodies and lifestyles it was associated
    with could help us understand its purpose.

    We humans take twice as long to grow up as our nearest relatives, the
    great apes. Instead of developing gradually from birth to adulthood,
    our growth rate slows dramatically over the first three years of life,
    and we grow just a few centimetres a year for the next eight years or
    so. Then suddenly, at puberty, growth accelerates again to as much as
    12 centimetres a year. Over the following three years adolescents grow
    an astonishing 15 per cent in both height and width. Though the
    teenage years are most commonly defined by raging hormones, the
    development of secondary sexual characteristics and attitude problems,
    what is unique in humans is this sudden and rapid increase in body
    size following a long period of very slow growth. No other primate has
    a skeletal growth spurt like this so late in life. Why do we?

    Until recently, the dominant explanation was that physical growth is
    delayed by our need to grow large brains and to learn all the complex
    behaviour patterns associated with humanity - speaking, social
    interaction and so on. While such behaviour is still developing,
    humans cannot easily fend for themselves, so it is best to stay small
    and look youthful. That way you do not eat too much, and your parents
    and other members of the social group are motivated to continue
    looking after you. What's more, studies of mammals show a strong
    relationship between brain size and the rate of development, with
    larger-brained animals taking longer to reach adulthood. Humans are at
    the far end of this spectrum.

    If this theory is correct, the earliest hominids, Australopithecus,
    with their ape-sized brains, should have grown up quickly, with no
    adolescent phase. So should H. erectus, whose brain, though twice the
    size of that of Australopithecus at around 850 cubic centimetres, was
    still relatively small. The great leap in brain capacity comes only
    with the evolution of our own species and Neanderthals, starting
    almost 200,000 years ago. Brains expanded to around 1350 cm3 in our
    direct ancestors and 1600 cm3 in Neanderthals. So if the development
    of large brains accounts for the teenage growth spurt, the origin of
    adolescence should be here. The trouble is, some of the fossil
    evidence seems to tell a different story.

    The human fossil record is extremely sparse, and the number of
    fossilised children minuscule. Nevertheless in the past few years
    anthropologists have begun to look at what can be learned of the lives
    of our ancestors from these youngsters. One of the most studied is the
    famous Turkana boy, an almost complete skeleton of H. erectus from 1.6
    million years ago found in Kenya in 1984. The surprise discovery is
    that there are some indications that he was a young teenager when he

    Accurately assessing how old someone is from their skeleton is a
    tricky business. Even with a modern human, you can only make a rough
    estimate based on the developmental stage of teeth and bones and the
    skeleton's general size. For example, most people gain their first
    permanent set of molars at age 6 and the second at 12, but the
    variation is huge. Certain other features of the skull also develop
    chronologically, although the changes that occur in humans are not
    necessarily found in other hominids. In the middle teenage years,
    after the adolescent growth spurt, the long bones of the limbs cease
    to grow because the areas of cartilage at their ends, where growth has
    been taking place, turn into rigid bone. This change can easily be
    seen on an X-ray.

    You need as many of these developmental markers as possible to get an
    estimate of age. The Turkana boy did not have his adult canines, which
    normally erupt before the second set of molars, so his teeth make him
    10 or 11 years old. The features of his skeleton put him at 13, but he
    was as tall as a modern 15-year-old. "By human standards, he was very
    tall for his dental age," says anthropologist Holly Smith from the
    University of Michigan at Ann Arbor. But you get a much more
    consistent picture if you look at Turkana boy in the context of
    chimpanzee patterns of growth and development. Then, his dental age,
    bone age and height all agree he was 7 or 8 years old. To Smith, this
    implies that the growth of H. erectus was primitive and the adolescent
    growth spurt had not yet evolved.

    Susan Anton of New York University disagrees. She points to research
    by Margaret Clegg, now at the University of Southampton in the UK,
    showing that even in modern humans the various age markers often do
    not match up. Clegg studied a collection of 18th and 19th-century
    skeletons of known ages from a churchyard in east London. When she
    tried to age the skeletons blind, she found the disparity between
    skeletal and dental age was often as great as that of the Turkana boy.
    One 10-year-old boy, for example, had a dental age of 9, the skeleton
    of a 6-year-old but was tall enough to be 11. "The Turkana kid still
    has a rounded skull, and needs a lot of growth to reach the adult
    shape," Anton adds. Like apes, the face and skull of H. erectus
    changed shape significantly between youth and adulthood. Anton thinks
    that H. erectus had already developed modern human patterns of growth,
    with a late, if not quite so extreme, adolescent spurt. She believes
    Turkana boy was just about to enter it.

    If she's right, and small-brained H. erectus went through a teenage
    phase, that scuppers the orthodox idea linking late growth with
    development of a large brain. Anthropologist Steven Leigh from the
    University of Illinois at Urbana-Champaign is among those who are
    happy to move on. He believes the idea of adolescence as catch-up
    growth is naive; it does not explain why the growth rate increases so
    dramatically. He points out that many primates have growth spurts in
    particular body regions that are associated with reaching maturity,
    and this makes sense because by timing the short but crucial spells of
    maturation to coincide with the seasons when food is plentiful, they
    minimise the risk of being without adequate food supplies while
    growing. What makes humans unique is that the whole skeleton is
    involved. For Leigh, this is the key. Coordinated widespread growth,
    he says, is about reaching the right proportions to walk long
    distances efficiently. "It's an adaptation for bipedalism," he says.

    According to Leigh's theory, adolescence evolved as an integral part
    of efficient upright locomotion, as well as to accommodate more
    complex brains. Fossil evidence suggests that our ancestors took their
    first steps on two legs as long as six million years ago. If
    proficient walking was important for survival, perhaps the teenage
    growth spurt has very ancient origins. Leigh will not be drawn,
    arguing that there are too few remains of young hominids to draw
    definite conclusions. While many anthropologists will consider Leigh's
    theory a step too far, he is not the only one with new ideas about the
    evolution of teenagers.

    A very different theory has been put forward by Barry Bogin from the
    University of Michigan-Dearborn. He believes adolescence in our
    species is precisely timed to improve the success of the first
    reproductive effort. In girls, notes Bogin, full adult shape and
    features are achieved several years before they reach full fertility
    at around the age of 18. "The time between looking fertile and being
    fertile allows women to practise social, sexual and cultural
    activities associated with adulthood, with a low risk of having their
    own children," says Bogin. When they finally do have children, they
    are better prepared to look after them. "As a result, firstborns of
    human mothers die much less often than firstborns of any other

    In boys, you see the opposite. They start producing viable sperm at 13
    or 14 years of age, when they still look like boys. The final increase
    in muscle size that turns them into men does not happen until 17 or
    18. In the interim boys, who feel like men, can practise male
    rivalries without being a threat to adult men or an attractive option
    to adult women. When boys do become sexually active, they have
    practised and are more likely to be successful without getting hurt.

    Bogin's theory makes totally different predictions to Leigh's. If the
    timing of adolescence is related to uniquely human cultural practices,
    our species should be the first and only one to have a teenage phase.
    "H. erectus definitely did not have an adolescence," he asserts. Such
    strong and opposing views make it all the more necessary to scour the
    fossil record for clues.

    One approach, which has produced a surprising result, relies on the
    minute analysis of tooth growth. Every nine days or so the growing
    teeth of both apes and humans acquire ridges on their enamel surface.
    These perikymata are like rings in a tree trunk: the number of them
    tells you how long the crown of a tooth took to form. Across mammals,
    the speed of tooth development is closely related to how fast the
    brain grows, the age you mature and the age you die. Teeth are good
    indicators of life history because their growth is less related to the
    environment and nutrition than is the growth of the skeleton. Slower
    tooth growth is an indication that the whole of life history was
    slowing down, including age at maturity.

    Back in the 1980s Christopher Dean, an anatomist at University College
    London, was the first to measure tooth growth in fossils using
    perikymata. He found that australopithecines dating from between 3 and
    4 million years ago had tooth crowns that formed quickly. Like apes,
    their first molars erupted at 4 years old and the full set of teeth
    were in place by 12. Over the years, Dean's team has collected enough
    teeth to show that H. erectus also had faster tooth growth than modern
    man, but not so fast as earlier hominids. "Things had moved on a bit,"
    he says. "They had their full set of teeth by about 15." Modern humans
    reach this stage by about age 20. The change in H. erectus seems to
    imply that the growth pattern of modern humans was beginning to
    develop, with an extended childhood and possibly an adolescent growth
    spurt. Dean cautions, though, that the link between dental and
    skeletal development in ancestral hominids remains uncertain.

    These findings could equally support Leigh's or Bogin's theories. A
    more decisive piece of evidence came last year, when researchers in
    France and Spain published their findings from an analysis of
    Neanderthal teeth. A previous study of a remarkably well-preserved
    skeleton of a Neanderthal youth, known as Le Moustier 1, from
    south-west France had suggested that, with a dental age of 15 and the
    frame of an 11-year-old, the kid was about to undergo an adolescent
    growth spurt. But the analysis of his perikymata reveals quite a
    different picture. Rather than continuing the trend towards slower
    development seen in H. erectus, Neanderthals had returned to much
    faster tooth growth (Nature, vol 428, p 936) and hence, possibly, a
    shorter childhood.

    Does this mean they didn't have an adolescence? Lead researcher
    Fernando Ramirez-Rozzi, of the French National Centre for Scientific
    Research (CNRS) in Paris thinks Neanderthals died young - about 25
    years oldprimarily because of the cold, harsh conditions they had to
    endure in glacial Europe. Under pressure from this high mortality,
    they evolved to grow up quicker than their immediate ancestors. "They
    probably reached maturity at about 15," he says, "but it could have
    been even younger." They would have matured too fast to accommodate an
    adolescent burst of growth. He points to research showing that
    populations of Atlantic cod have genetically changed to mature more
    quickly under the intense fishing pressure of the 1980s. Others
    contest Ramirez-Rozzi's position. "You can't assume, just because
    Neanderthals' teeth grew faster, that their entire body developed
    faster," says Jennifer Thompson of the University of Nevada, Las
    Vegas, one of the researchers involved in the Le Moustier 1 study.

    Controversy rages, but these latest findings at least highlight one
    aspect of adolescence that most scientists can agree on. Whatever the
    immediate purpose of the late growth spurt, it was made possible by an
    increase in life expectancy. And that being so, one way to work out
    when the first teenagers originated is to look at the lifespan of a
    species. This is exactly what Rachel Caspari of the University of
    Michigan at Ann Arbor has been doing. Her most recent study, published
    in July 2004, shows an astonishing increase in longevity that
    separates modern Homo sapiens from all other hominids, including
    Neanderthals (Proceedings of the National Academy of Sciences, vol
    101, p 10895). She categorised adult fossils as old or young by
    assessing whether they had as much wear on their last molar, or wisdom
    tooth, as on other molars. "In modern humans we see a massive increase
    in the number of people surviving to be grandparents," she says. The
    watershed comes as recently as 30,000 years ago.

    On this evidence, Neanderthals and H. erectus probably had to reach
    adulthood quickly, without delaying for an adolescent growth spurt. So
    it looks as though Bogin is correct we are the original teenagers.
    Whether he is right about the purpose of adolescence is another
    matter. He admits we will never know for sure. "Fossils will never
    give us growth curves," he says, "and we should not expect our
    ancestors to grow like we do."
    Printed on Tue Mar 08 20:56:28 GMT 2005


Instant Expert: Teenagers

    The teenager is a [1]uniquely human phenomenon.

    Adolescents are known to be moody, insecure, argumentative,
    [2]angst-ridden, impulsive, [3]impressionable, reckless and
    rebellious. Teenagers are also characterised by [4]odd sleeping
    patterns, awkward [5]growth spurts, [6]bullying, [7]acne and
    [8]slobbish behaviour. So what could be the possible benefit of the
    teenage phase?

    Most other animals - apes and human ancestors included - skip that
    stage altogether, developing rapidly from infancy to full adulthood.
    Humans, in contrast, have a very puzzling four-year gap between sexual
    maturity and prime reproductive age. Anthropologists disagree on when
    the [9]teenage phase first evolved, but pinpointing that date could
    help define its purpose.

    There are a variety of current explanations for the existence of
    teenagers. Some believe that we need longer for our [10]large brains
    to develop. Other explanations suggest that a teenage phase allows
    kids to learn about [11]complex social behaviour and [12]other
    difficult skills, or that it is even required to develop coordinated
    bipedal bodies adapted to [13]travelling long distances.

Raging hormones

    Scientists once thought that the brain's internal structure was fixed
    at the end of childhood, and teenage behaviour was blamed on raging
    hormones and a lack of experience. Then researchers discovered that
    the brain [14]undergoes significant changes during adolescence.

    According to many recent studies, teen brains really are unique (see
    interactive graphic). Though many brain areas mature during childhood,
    [15]others mature later - such as the frontal and parietal lobes,
    responsible for planning and self-control.

    Other studies have shown that teens [16]fail to see the consequences
    of their actions, and that [17]sudden increases in nerve connectivity
    in teen brains may make it difficult for teenagers to read social
    situations and other people's emotions.

Risky behaviour

    One study in 2004 showed that teens have less brain activity in areas
    responsible for [18]motivation and risk assessment, perhaps explaining
    why they are more likely to take part in [19]risky activities such as
    [20]abusing drugs and alcohol, develop a [21]hard-to-kick smoking
    habit or indulge in [22]under-age sex.

    Teenage pregnancies and rising rates of sexually transmitted diseases
    among teens are big problems - especially because today's teen
    generation is the [23]biggest the world has seen: a 2003 UN report
    revealed that 1 in 5 people were between 10 and 19, a total of 1.2
    billion people.

    But not everyone agrees on the best way to tackle the problem. Some
    believe that comprehensive [24]sex education is the key, while others
    argue for [25]abstinence only education courses.

    John Pickrell, 3 March 2004


    1. http://www.newscientist.com/channel/being-human/teenagers/dn1654
    2. http://www.newscientist.com/channel/being-human/teenagers/dn2925
    3. http://www.newscientist.com/channel/being-human/teenagers/dn3812
    4. http://www.newscientist.com/channel/being-human/teenagers/mg18524811.700
    5. http://www.newscientist.com/channel/being-human/teenagers/mg13818715.600
    6. http://www.newscientist.com/channel/being-human/teenagers/mg18524891.100
    7. http://www.newscientist.com/channel/being-human/teenagers/mg17623742.500
    8. http://www.newscientist.com/channel/being-human/teenagers/mg14219223.600
    9. http://www.newscientist.com/channel/being-human/teenagers/mg18524891.100
   10. http://www.newscientist.com/channel/being-human/teenagers/mg13618505.000
   11. http://www.newscientist.com/channel/being-human/teenagers/mg13718634.500
   12. http://www.newscientist.com/channel/being-human/teenagers/mg17623725.300
   13. http://www.newscientist.com/channel/being-human/teenagers/dn6681
   14. http://www.newscientist.com/channel/being-human/teenagers/mg17623650.200
   15. http://www.newscientist.com/channel/being-human/teenagers/mg16522224.200
   16. http://www.newscientist.com/channel/being-human/teenagers/dn6738
   17. http://www.newscientist.com/channel/being-human/teenagers/dn2925
   18. http://www.newscientist.com/channel/being-human/teenagers/dn4718
   19. http://www.newscientist.com/channel/being-human/teenagers/dn4460
   20. http://www.newscientist.com/channel/being-human/teenagers/mg13718594.000
   21. http://www.newscientist.com/channel/being-human/teenagers/dn4163
   22. http://www.newscientist.com/channel/being-human/teenagers/dn6957
   23. http://www.newscientist.com/channel/being-human/teenagers/dn4253
   24. http://www.newscientist.com/channel/being-human/teenagers/mg18324580.800
   25. http://www.newscientist.com/channel/being-human/teenagers/dn6957

Adolescence unique to modern humans

      * 12:25 06 December 2001
      * Claire Ainsworth

    The uniquely human habit of taking 18 years or so to mature is a
    recent development in our evolutionary history. Growth patterns of
    fossil teeth have shown that a prolonged growing-up period evolved
    long after our ancestors started walking upright and making tools.

    Our great ape relatives, the chimpanzees and gorillas, take about 11
    years to reach adulthood. Scientists speculate that delaying this
    process allows children to absorb our complex languages, culture and
    family relationships.

    What's more, we need extra time for our large brains to grow - they
    are half as big again as those of the earliest humans, Homo erectus,
    who appeared some 2 million years ago.

    Christopher Dean of University College London and his team studied
    teeth from H. erectus, our Australopithecus human-like ancestors such
    as the famous "Lucy", and Proconsul nyanzae, an ape ancestor. The rate
    of tooth development is tightly linked to how long it takes to become
    fully grown.

Teeth rings

    Teeth grow by adding on enamel in small increments, leaving striations
    rather like shell ridges or tree rings. By studying these rings, the
    team could work out how fast the teeth grew.

    They found that H. erectus's teeth grew at almost the same rate as
    those of both modern and fossil apes and Australopithecus - suggesting
    a shorter growing-up period.

    This was surprising, as H. erectus walked upright, was about the same
    size as us and made simple tools - all traits associated with being
    human, says Dean. But it fits with the fact that H. erectus's brain
    was much smaller.

    By comparing the growth rate of the back and front teeth, the team
    estimated that H. erectus children produced their first permanent
    molars at around 4.5 years, and their second at 7.5 years. This
    compares with 6 and 12 years in modern humans and 3 and 5 years for
    modern apes, indicating that H. erectus was starting down the road of
    modern dental development.

    Journal reference: Nature (vol 414, p 628)

Related Articles

      * [13]Old bones may be earliest human ancestor
      * 11 July 2001
      * [14]A 3.5 million year-old skull unearthed in Kenya may force a
        re-examination of the evolution of modern humans
      * 21 March 2001
      * [15]The most ancient human-like remains are unearthed in Kenya
      * 5 December 2000


      * [16]Human Origins
      * [17]Evolutionary Anatomy Unit, UCL
      * [18]Nature


   13. http://www.newscientist.com/article.ns?id=dn995
   14. http://www.newscientist.com/article.ns?id=dn542
   15. http://www.newscientist.com/article.ns?id=dn240
   16. http://www.mnh.si.edu/anthro/humanorigins/
   17. http://evolution.anat.ucl.ac.uk/
   18. http://www.nature.com/
Teen angst rooted in busy brain
      * 19:00 16 October 2002
      * Duncan Graham-Rowe

    Scientists believe they have found a cause of adolescent angst. Nerve
    activity in the teenaged brain is so intense that they find it hard to
    process basic information, researchers say, rendering the teenagers
    emotionally and socially inept.

    Robert McGivern and his team of neuroscientists at San Diego State
    University, US, found that as children enter puberty, their ability to
    quickly recognise other people's emotions plummets. What is more, this
    ability does not return to normal until they are around 18 years old.

    McGivern reckons this goes some way towards explaining why teenagers
    tend to find life so unfair, because they cannot read social
    situations as efficiently as others.

    Previous studies have shown that puberty is marked by sudden increases
    in the connectivity of nerves in parts of the brain. In particular,
    there is a lot of nerve activity in the prefrontal cortex. "This plays
    an important role in the assessment of social relationships, as well
    as planning and control of our social behaviour," says McGivern.

Western turmoil

    He and his team devised a study specifically to see whether the
    prefrontal cortex's ability to function altered with age. Nearly 300
    people aged between 10 and 22 were shown images containing faces or
    words, or a combination of the two. The researchers asked them to
    describe the emotion expressed, such as angry, happy, sad or neutral.

    The team found the speed at which people could identify emotions
    dropped by up to 20 per cent at the age of 11. Reaction time gradually
    improved for each subsequent year, but only returned to normal at 18.

    During adolescence, social interactions become the dominant influence
    on our behaviour, says McGivern. But at just the time teenagers are
    being exposed to a greater variety of social situations, their brains
    are going through a temporary "remodelling", he says. As a result,
    they can find emotional situations more confusing, leading to the
    petulant, huffy behaviour for which adolescents are notorious.

    But this may only be true for Western cultures. Adolescents often play
    a less significant role in these societies, and many have priorities
    very different from their parents', leading to antagonism between
    them. This creates more opportunity for confusion. "One would expect
    to observe a great deal more emotional turmoil in such kids," he says.

    Journal reference: Brain and Cognition (vol 50, p 173)

Related Articles

      * [12]Brain expression response linked to personality
      * 20 June 2002
      * [13]Angry outbursts linked to brain dysfunction
      * 27 May 2002
      * [14]Physical changes may be responsible for 'feeling' emotions
      * 19 September 2000


      * [15]Psychology, San Diego State University
      * [16]Early Experience and Brain Development research
      * [17]Brain and Cognition


   12. http://www.newscientist.com/article.ns?id=dn2439
   13. http://www.newscientist.com/article.ns?id=dn2331
   14. http://www.newscientist.com/article.ns?id=dn3
   15. http://www.psychology.sdsu.edu/
   16. http://www.macbrain.org/
   17. http://www.academicpress.com/b&c

Movie smoking encourages kids to light up
      * 13:14 10 June 2003
      * Shaoni Bhattacharya

    Watching movie stars light up on screen is the biggest single factor
    in influencing teenagers to smoke, suggests a new US study.

    Adolescents who had never smoked were almost three times more likely
    to then take up the habit if they had watched films packed with
    smoking scenes, compared to their peers who had seen films with the
    least amount of on-screen smoking.

    "There was a tremendous impact," says research leader Madeline Dalton,
    at Dartmouth Medical School in Hanover, New Hampshire. "Movies were
    the strongest predictor of who would go on to smoke - stronger than
    peers smoking, family smoking, or the personality of the child."

    "We know from past studies it's very rare for smoking to be portrayed
    in a negative light. Smokers [in movies] tend to be tough guys or
    sexy, rebellious women - which appeal to adolescents," she told New

    Dalton's colleague Michael Beach adds: "Our data indicate that 52 per
    cent of smoking initiation among adolescents in this study can be
    attributed to movie smoking exposure."

    "The effect is stronger than the effect of traditional cigarette
    advertising and promotion, which accounts for 'only' 34 per cent of
    new experimentation," notes Stanton Glantz, at the Center for Tobacco
    Control Research and Education, in an editorial accompanying the study
    published online in The Lancet.

Smoke screen

    The study began by recruiting over 2600 US schoolchildren aged 10 to
    14 who had never smoked. Each child was then asked if they had watched
    any of 50 movies randomly selected from 601 box office hits released
    between 1988 and 1999. The number of occurrences of smoking in each
    film was recorded by trained coders.

    When followed up one to two years later, 10 per cent of the children
    had tried smoking. Those in the top quarter of exposure to movie
    smoking were 2.7 times more likely to have tried a cigarette than
    those in the lowest quarter of exposure. This effect was independent
    of other factors that might influence the child's smoking behaviour,
    such as friends or family smoking.

    "It's more evidence that movies have a strong impact on adolescents,"
    says Dalton. "Previous studies have suggested that smoking in movies
    influences adolescent smoking behaviour, but this is the first study
    to show that viewing smoking in movies predicts who will start smoking
    in the future."

    Dalton, an expert in cancer risk behaviour in children, says a
    previous study by the team showed that children were more likely to
    smoke if their favourite actor smoked.

    Movies which depict smoking should be given an adult rating or "R
    rating" in the US, suggests Glantz, which would mean that children
    under 17 could not see the film without a parent. "An R rating for
    smoking in movies would prevent about 330 adolescents [in the US] from
    starting to smoke and ultimately extend 170 lives every day," he

    Journal reference: The Lancet (vol 361, no 9373, early online

Related Articles

      * [12]Controversy over passive smoking danger
      * 16 May 2003
      * [13]Violent song lyrics increase aggression
      * 4 May 2003
      * [14]Public smoking ban slashes heart attacks
      * 1 April 2003


      * [15]Dartmouth Medical School
      * [16]Center for Tobacco Control Research and Education
      * [17]Action on Smoking and Health, UK
      * [18]The Lancet


   12. http://www.newscientist.com/article.ns?id=dn3737
   13. http://www.newscientist.com/article.ns?id=dn3695
   14. http://www.newscientist.com/article.ns?id=dn3557
   15. http://www.dartmouth.edu/dms/index.shtml
   16. http://repositories.cdlib.org/ctcre/
   17. http://www.ash.org.uk/
   18. http://www.thelancet.com/home

Bedtimes could pinpoint the end of adolescence
      * 08 January 2005
      * Andy Coghlan

    AT WHAT point does adolescence end? Perhaps at the point when we start
    to go to bed progressively earlier rather than later and later.

    The end of puberty, or sexual maturation, is well defined. It is the
    point when bones stop growing, at around age 16 for girls and 17.5 for
    boys. But for adolescence, the transition from childhood to adulthood,
    there is no clear endpoint.

    "I don't know of any markers for it," says Till Roenneberg of the
    Centre for Chronobiology at the University of Munich in Germany.
    "Everyone talks about it but no one knows when adolescence ends. It is
    seen as a mixed bag of physical, psychological and sociological

    His suggestion is based on a study of the sleep habits of 25,000
    individuals of all ages in Switzerland and Germany. The study looked
    at when people go to sleep during vacations, when they are free to
    sleep any time. It reveals a distinct peak of night-owlishness at
    around age 20. Women reach this peak at 19.5 years old on average, and
    men at 20.9 years. After that, individuals gradually return to earlier
    and earlier sleeping patterns, until things go haywire in old age.

    Roenneberg, whose findings appear in Current Biology (vol 14, p
    R1038), thinks that the peak in lateness is the first plausible
    biological marker for the end of adolescence.

    The study confirms that 20-year-olds sleep any time except in the
    evening, says Malcolm von Schantz of the Surrey Sleep Research Centre
    at the University of Surrey, UK. "Don't I know it - they're in my

    The suggestion that this peak in sleep habits marks the end of
    adolescence is intriguing, he says, but more research will be needed
    to prove these behavioural changes are a result of physiological
    changes, rather than lifestyle. "A lot of things happen to you around
    this age," von Schantz points out.

    If it is a physiological effect, forcing teenagers to get to school
    for, say, 8 am, could be a mistake, Roenneberg says. They probably
    take nothing in for the first two lessons because they are still in
    biological "sleep time", and end up with a horrendous sleep deficit by
    the weekend.

Letters: Growth spurts
      * 01 May 1993

    Barry Bogin has written a marvellous explanation about why we go
    through the adolescent growth spurt ('Why must I be a teenager at
    all?', 6 March). We can equally marvel at another spurt not often
    mentioned by biologists and anthropologists, namely the mid-childhood
    spurt occurring between ages six and eight. It varies in magnitude and
    shows itself as a mere blip on Bogin's growth rate curve, but it has a
    very interesting history.

    First, it is an opportunity for body growth to get its due after so
    many years of devoting unequal resources to growing a large brain.
    Every parent will attest to the struggle of dressing children and the
    seeming incoherence of a clothing industry that makes pullovers to fit
    little bodies that have to pull them over a brain which is nearly 95
    per cent of its adult size at 6 years of age.

    Second, this spurt is related to the adolescent spurt in developed
    nations. Puberty is not only the time of accelerated growth, it marks
    the beginning of the end of growth too. In order for adolescents to
    reach the normal height for their population they must be so far along
    by the time puberty hits them. Thus for children with relatively short
    pre-pubertal growth periods, an extra push is needed early on (the
    mid-childhood spurt) to get them to their right preadolescent height
    before the pubertal growth spurt.

    Children of populations with puberty closer to 16 years of age, such
    as those of some underdeveloped nations, do not experience the
    mid-childhood spurt because they have more prepubertal time to grow

    Tim Bromage City University of New York


Spotty genes - News
      * 21 December 2002

    HERE'S something else grumpy teenagers can blame their parents for -
    their zits.

    In a study of identical and non-identical twins, Veronique Bataille of
    St Thomas' Hospital in London and her team have shown that acne is 80
    per cent genetic. Environmental factors, such as eating the wrong
    foods or wearing greasy make-up, are relatively unimportant. They will
    report their results in The Journal of Investigative Dermatology.

    Finding the genes involved could clarify what triggers acne, and
    possibly lead to cheaper, more effective treatments. Worldwide,
    prescription drugs for acne cost about $4 billion each year.

Fine young slobs?: Kids who spend hours hunched in front of television or 
computer screens may look as healthy as their active brothers and sisters. But 
are they storing up trouble?  Helen Saul reports
      * 23 April 1994
      * HELEN SAUL

    A teenage computer games addict sits engrossed in front of a screen,
    hardly moving for hours on end. A parent, worried about strangers and
    excessive traffic on the roads, insists on driving the children to
    school. Increasing pressure on children to perform well in academic
    subjects relegates physical exercise to the bottom of the priority
    list at school.

    It all seems like a recipe for weak bodies and illness. But are
    today's children and adolescents really as sedentary and unfit as
    popular images would have us believe? And if they are, what should be
    done to persuade them to be more active?

    On the face of it, the facts are hardly encouraging. The Broadcasting
    Audience Research Board's figures for 1993 show that in Britain
    children between the ages of four and 15 watch an average of between
    two and three hours of TV each day. The National Curriculum for
    schools allocates an average of only one hour a week for physical
    education, and in practice less than 10 per cent of this time is spent
    exercising. Moreover, as many as one in three children do less than
    the equivalent of a 10-minute walk each day, according to Neil
    Armstrong and his research team at the University of Exeter.

    Yet just as politicians in Britain want to see a return to
    competitive, team-oriented sport in schools, experts are stressing the
    need for exercise regimes geared for individuals which require a
    minimum of formal training. Researchers, meanwhile, are busy
    questioning the underlying assumptions that today's young couch
    potatoes are physically weaker than their supposedly more active

    For children, it may be a mistake to equate physical inactivity with
    low physical fitness, says Armstrong. He and his colleagues have spent
    the past nine years monitoring the links between exercise and fitness
    in some 700 children, aged between 9 and 16. Part of this endeavour
    has involved measuring how the hearts and lungs of some of these
    children perform during strenuous exercise. The result is surprising:
    the hearts and lungs of inactive children perform just as well as
    those of habitually active children - and just as well as those of
    children of previous generations. 'There's no scientific evidence to
    show that children are less fit than they used to be,' says Armstrong

    So childhood laziness is no bad thing? Not quite. Physical fitness is
    clearly influenced by a myriad factors other than exercise, including
    genetics and diet. It also means different things to different people:
    a long-distance runner and a weightlifter are both physically fit, but
    in different ways and because of different exercise regimes. The way
    hearts and lungs respond to aerobic activity is certainly one measure
    of physical fitness. But the strength and stamina of skeletal muscles
    may be just as important. Exactly how important is unclear, for few
    long-term studies of the effects of exercise on children have
    attempted to examine all these factors.

    What's more, even if childhood laziness does not erode physical
    fitness immediately, children who fail to form the 'exercise habit'
    are likely to regret it later in life. Studies of adults show that a
    sedentary lifestyle is as likely to cause heart disease as high blood
    pressure, smoking or high cholesterol levels. People who fail to take
    physical exercise are thought to be twice as likely contracting
    coronary heart disease. They also run higher-than-average risks of
    developing breast cancer, diabetes and osteoporosis. In the US alone,
    physical inactivity is estimated to cause 250 000 deaths a year.

    Treadmill test

    Adults who don't exercise also perform badly on tests of heart and
    lung fitness. Put them on a treadmill or cycle ergometer and measure
    their aerobic fitness by monitoring oxygen uptake, heart rate and
    carbon dioxide exhaled and you will find that their lungs can't take
    up as much oxygen as their active counterparts. Armstrong and his
    colleagues wanted to find out if the same was true for children. So
    they tested 420 children, measuring their oxygen uptake as they
    exercised on treadmills or cycle ergometers. The tests supported the
    results of similar tests carried out some fifty years ago in Chicago.
    The study also shows that, in contrast to adults, active children
    perform no better in tests of aerobic fitness than children who don't.
    Studies in other parts of the world show a similar trend, says

    Steven Blair, director of epidemiology at the Cooper Institute for
    Aerobics Research in Dallas, believes that one in five children in the
    US is physically unfit. But he agrees with Armstrong that the limited
    data available suggest there has been no major change in physical
    fitness among young Americans over the past few decades. 'It's very
    popular in the States for people to dash about saying 'It's terrible.
    It's getting worse. More and more children are getting more and more
    unfit.' But how do they know that?'

    The links between exercise and fitness in children have always been
    uncertain. It is doubtful that studies based on any one measure of
    fitness can resolve the main questions. This is certainly true of
    tests based on oxygen uptake. For one thing, oxygen uptake varies from
    child to child because of genetic differences that influence muscle
    growth, strength of the heart and so on. It could be that peak oxygen
    uptake is too crude a measure to pick up a slight deterioration in
    lung and heart fitness. Moreover, even if the hearts and lungs of
    children do not weaken with lack of exercise, that does not
    necessarily mean that inactive children are physically fit in a
    broader sense.

    Yet there are other signs that exercise may not be as important to the
    fitness of children as it is to adults. In adults, for instance, there
    is a clear link between physical exercise and blood levels of high
    density lipoprotein, or 'good' cholesterol. This substance acts to
    prevent the clogging up of arteries that is caused by high levels of
    'bad' cholesterol, or low-density lipo-protein. The more exercise
    people take, the higher their HDL levels and the more favourable the
    ratio between HDL and LDL, which remains constant. But there is no
    evidence that the same is true in children.

    This, however, may be no reason to celebrate. If children can't feel
    the physical benefits of exercise, won't it prove harder to persuade
    them of its value? 'There's no way you can convince 15-year-olds that
    by being more active today, they'll be less likely to get coronary
    heart disease when they're 50,' says Oded Bar-Or, professor of
    exercise sciences at McMaster University in Hamilton, Ontario.

    The problem is compounded by the fact that inactivity often goes hand
    in hand with eating too many fatty or sugary foods. More than two in
    five children in Britain have total cholesterol levels (combined LDL
    and HDL levels) above the American Health Foundation's safety limit.
    This is calculated from the cholesterol level in adults that is known
    to increase the risk of heart disease, taking into account the fact
    that cholesterol levels increase gradually with age.

    All the signs are that most children are not active enough to form the
    kind of exercise habit that could protect them from ill health later
    in life. As part of the Exeter study, for instance, researchers used
    portable heart monitors to capture the heart rates of some 266
    children from 9.00 am until 9.00 pm. The portable devices used a small
    transmitter on the chest to send the heart rate data to a receiver on
    a wrist band. Previously, the researchers had established that, on
    average, the heart rate of children walking on a treadmill at 6
    kilometres per hour is 140 beats per minute. From this, it was
    possible to calculate that a third of the boys and half of the girls
    do not even do the equivalent of a brisk 10-minute walk a day.

    But not everyone is pessimistic. Drawing on data reported in 43
    different epidemiological studies, Blair concludes that children and
    adults alike can reduce the risk of heart disease later in life by
    burning off just three kilocalories per kilogram of body weight per
    day. For a child weighing 40 kilograms, this amounts to 120 kcal a day
    - equivalent to the energy contained in an average biscuit. In a study
    of 1800 boys and girls aged between 10 and 18 years, Blair found that
    the most met this standard.

    Exercise habit

    That said, most researchers see no harm in encouraging all children to
    be more active. 'It's all pluses,' says Armstrong. The biggest plus of
    all is that having developed an exercise habit, a child may be more
    likely to retain it throughout adulthood. But do active children
    necessarily become active adults?

    What little evidence there is suggests the answer is yes. In 1990,
    researchers in Britain questioned more than 4000 adults on their
    behaviour, attitudes and beliefs about activity and fitness as part of
    the Allied Dunbar National Fitness Survey. A quarter of those who said
    that they were active as teenagers also said that they were active as
    adults. Only two per cent of those who said that they were inactive at
    the younger age said that they were active as adults.

    Ken Fox, who lectures in physical exercise at the University of
    Exeter, believes that what motivates people to do exercise shifts over
    time. Overemphasising sports and team games is one reason why
    adolescents drop out, he says. This is particularly true of girls
    whose participation in exercise during adolescence falls off more
    dramatically than that of boys. Groups of girls may not value
    formalised activities such as competitive sport, he says. 'But
    aerobics and dance may be more socially acceptable to some groups of
    girls. And if they value these activities, they're more likely to make
    the decision to take part.'

    Bill Kohl, director of the division of childhood and adolescent
    medicine at the Cooper Institute of Aerobic research, says: 'Fitness
    and activity is for all kids, not just for those who are athletically
    gifted. It's not necessary to run a marathon or be Sebastian Coe to
    get health benefits from physical activity.

    Helen Saul is a freelance writer specialising in health and medicine.

Teenagers special: Brain storm
      * 05 March 2005

Prefrontal cortex

    The prefrontal cortex is the home of "executive" functioning,
    high-level cognitive processes that, among other things, allow us to
    develop detailed plans, execute them, and block irrelevant actions.

    This area undergoes a bulking up between the ages of 10 and 12,
    followed by a dramatic decline in size that continues into the early
    20s. This is probably due to a burst of neuronal growth followed by a
    "pruning" stage in which pathways that are not needed are lost.

    If the adolescent's brain is still bedding down its executive
    functions, this might help explain why teenagers can sometimes seem so
    disorganised and irrational.

Right ventral striatum

    This area of the brain is thought to be involved in motivating
    reward-seeking behaviour.

    A study last year showed that teenagers had less activity than adults
    in this part of the brain during a reward-based gambling game. The
    researchers speculate that teens may be driven to risky but
    potentially high-reward behaviours such as shoplifting and drug-taking
    because this area is underactive.

Pineal gland

    The pineal gland produces the hormone melatonin, levels of which rise
    in the evening, signalling to the body that it is time to sleep.

    During adolescence melatonin peaks later in the day than in children
    or adults. This could be why teenagers tend to be so fond of late
    nights and morning lie-ins.

Corpus callosum

    These are nerve fibres linking the left and right sides of the brain.

    The parts thought to be involved in language learning undergo high
    growth rates before and during puberty, but this growth then slows.
    This might help explain why the ability to learn new languages
    declines rapidly after the age of 12.


    This part of the brain continues to grow until late adolescence. It
    governs posture and movement, helping to maintain balance and ensure
    that movements are smooth and directed. It influences other regions of
    the brain responsible for motor activity and may also be involved in
    language and other cognitive functions.
Teenagers special: Going all the way
      * 05 March 2005
      * Alison George

    LYNSEY TULLIN was 15 when she became pregnant. The only contraception
    she and her boyfriend had used was wishful thinking: "I didn't think
    it would happen to me," she says. Tullin, who lives in Oldham in
    northern England, decided to keep the baby, now aged 3, although as a
    consequence her father has disowned her.

    Tullin is not alone. In the UK nearly 3 per cent of females aged 15 to
    19 became mothers in 2002, many of them unintentionally. And unplanned
    pregnancies are not the only consequence of teenage sex - rates of
    sexually transmitted diseases (STDs) are also rocketing in British
    adolescents, both male and female.

    The numerous and complex societal trends behind these statistics have
    been endlessly debated without any easy solutions emerging. Policy
    makers tend to focus on the direct approach, targeting young
    adolescents in the classroom. In many western schools teenagers get
    sex education classes giving explicit information about sex and
    contraception. But recently there has been a resurgence of some
    old-fashioned advice: just say no. The so-called abstinence movement
    urges teens to take virginity pledges and cites condoms only to stress
    their failure rate. It is sweeping the US, and is now being exported
    to countries such as the UK and Australia.

    Confusingly, both sides claim their strategy is the one that leads to
    fewest pregnancies and STD cases. But a close look at the research
    evidence should give both sides pause for thought. It is a morally
    charged debate in which each camp holds entrenched views, and opinions
    seem to be based less on facts than on ideology. "It's a field fraught
    with subjective views," says Douglas Kirby, a sex education researcher
    for the public-health consultancy ETR Associates in Scotts Valley,

    For most of history, pregnancy in adolescence has been regarded not as
    a problem but as something that is normal, so long as it happens
    within marriage. Today some may still feel there is nothing unnatural
    about older adolescents in particular becoming parents. But in
    industrialised countries where extended education and careers for
    women are becoming the norm, parenthood can be a distinct
    disadvantage. Teenage mums are more likely to drop out of education,
    to be unemployed and to have depression. Their children run a bigger
    risk of being neglected or abused, growing up without a father,
    failing at school and abusing drugs.

    The US has by far the highest number of teenage pregnancies and births
    in the west; 4.3 per cent of females aged between 15 and 19 gave birth
    there in 2002. This is significantly higher than the rate in the UK
    (2.8 per cent), which itself has the highest rate in western Europe
    (see Chart).

    Another alarming statistic is the number of teenagers catching STDs.
    In the UK the incidences of chlamydia, syphilis and gonorrhoea in
    under-20s have all more than doubled since 1995. The biggest rise has
    been in chlamydia infections in females under 20; cases have more than
    tripled, up to 18,674 in 2003. Chlamydia often causes no symptoms for
    many years but it can lead to infertility in women and painful
    inflammation of the testicles in men.

    No surprise, then, that teenage sex and pregnancy has become a
    political issue. The UK government has set a target to halve the
    country's teen pregnancy rate by 2010, and the US government has set
    similar goals. But achieving these targets will not be easy. In an age
    when adolescence has never been so sexualised, in most western
    countries people often begin to have sex in their mid to late teens;
    by the age of 17, between 50 and 60 per cent are no longer virgins.

    Since the 1960s, UK schools have increasingly accepted that many
    teenagers will end up having sex and have focused efforts on trying to
    minimise any ensuing harm. Sex education typically involves describing
    the mechanics of sex and explaining how various contraceptives work,
    with particular emphasis on condoms because of the protection they
    provide from many STDs.

    The sex education strategy gained further support in the early 1990s
    when policy makers looked to the Netherlands. There, teenage birth
    rates have plummeted since the 1970s and are now among the lowest in
    Europe, with about 0.8 per cent of females aged between 15 and 19
    giving birth in 2002. No one knows why for sure, as Dutch culture
    differs from that of the UK and America in several ways. But it is
    generally attributed to frank sex education in schools and open
    attitudes to sex. Dutch teenagers, says Roger Ingham, director of the
    Centre for Sexual Health Research at the University of
    Southampton,"have less casual sex and are older when they first have
    sex compared with the UK".

    But a new sexual revolution is under way. Spearheaded by the religious
    right, the so-called abstinence movement is based on the premise that
    sex outside marriage is morally wrong. "We're trying to say there's
    another approach to your sexuality," says Jimmy Hester, co-founder of
    one of the oldest pro-abstinence campaigns, True Love Waits, based in
    Nashville, Tennessee.

    Abstinence-based education got US government backing in 1981, when
    Congress passed a law to fund sex education that promoted
    self-restraint. More money was allocated through welfare laws passed
    in 1996, which provided $50 million a year.

    A key plank of the abstinence approach is to avoid giving advice on
    contraception. The logic is that such information would give the
    message that it's OK to have sex. "The moment we do that, we water
    down the commitment," says Hester.

    If contraception is mentioned at all, it is to highlight its failings
    - often using inaccurate or distorted data. A report for the US House
    of Representatives published last December found that 11 out of the 13
    federally funded abstinence programmes studied contained false or
    misleading information. Examples of inaccurate statements included:
    "Pregnancy occurs one out of every seven times that couples use
    condoms," and: "Condoms fail to prevent HIV 31 per cent of the time."
    They also use some questionable logic regarding the success rate of
    abstinence (see "Heads I win, tails you lose").

    While some states advocate "abstinence-plus" programmes, providing a
    level of advice on contraception alongside heavy promotion of
    chastity, the hard-line "abstinence only" approach is in the ascendant
    in the US. Around a third of US secondary schools have abstinence-only
    programmes, and nearly 3 million young people have publicly pledged to
    remain virgins until they marry.

    And it is spreading. Last June an American group came to the UK to
    promote the Silver Ring Thing, a Christian movement that encourages
    teens to publicly pledge to remain virgins until marriage and to keep
    their promise with the aid of a $12 ring. And True Love Waits has held
    virginity rallies in Australia.

    This trend comes amid claims that the UK's more liberal approach not
    only does not work, but has the opposite effect. "Free pills and
    condoms boost promiscuity" screamed the headline on the front page of
    UK newspaper The Times last year (5 April 2004). It was prompted by
    research by David Paton, an economist at the University of Nottingham,
    UK, which found that in some areas that had increased access to family
    planning services, teen pregnancy rates had remained the same and STD
    rates had actually risen.

    There are now increasing calls from conservative and religious groups
    for schools in the UK to consider the abstinence option. A programme
    called Love for Life is now operating in 60 per cent of schools in
    Northern Ireland. It could be described as abstinence-plus that is
    heavy on the abstinence. Its founder, Richard Barr, a GP from
    Craigavon, County Armagh, says that focusing on contraception ignores
    the bigger picture of human sexuality. "There's a massive need for a
    more holistic approach, not just a damage-limitation approach."

    And the UK mainland is home to a small but growing number of groups,
    most of them with Christian roots, promoting abstinence-centred
    education. The word abstinence is less in vogue than across the
    Atlantic, however, and such groups are more likely to talk in terms of
    delaying sex until young people are in a committed relationship.

    But does the abstinence approach work? Do teenagers - a group not
    renowned for their propensity to do what they are told - take any
    notice when adults tell them not to have sex?

    Proponents of abstinence claim research supports their strategy. But
    the vast majority of studies that have been done in this area have
    been small, short-term evaluations without control groups. "There have
    only been three well-designed trials where an 'intervention' group is
    compared with a control group and participants are tracked over time,"
    says Kirby.

    One of these, published in 1997, looked at a five-session
    abstinence-only initiative in California. The trial tracked 10,600
    teenagers for 17 months (Family Planning Perspectives, vol 29, p 100).
    The researchers found it had no impact on the sexual behaviour or
    pregnancy rates of teenagers. The other two studies had similar
    results. "None of them show that any abstinence-only programmes had
    any impact on behaviour," says Kirby.

    Although not a controlled trial, one of the largest studies of the
    effect of abstinence pledges tracked the sex lives of 12,000 US
    teenagers aged between 12 and 18 (American Journal of Sociology, vol
    106, p 859). A group led by Peter Bearman, a sociologist at Columbia
    University in New York, investigated whether taking a virginity pledge
    affected the age when people first had sex. It did, with an average
    delay of 18 months. The pledgers also got married earlier and had
    fewer partners overall.

    But when Bearman went back six years later and looked at the STD rates
    in the same people, now aged between 18 and 24, he was in for a
    surprise. In research presented at the National STD conference in
    Philadelphia last year, he found that though pledgers had had fewer
    sexual partners than non-pledgers, they were just as likely to have
    had an STD. And the reason? "Pledgers use condoms less," says Bearman.
    "It's difficult to simultaneously imagine not intending to have sex
    and being contraceptively prepared."

    Here lies the problem that many have with the idea of abstinence-only
    education. While it may work for those kids who live up to the ideal,
    those who don't are left without the knowledge to protect themselves
    when they do have sex. "It's not rocket science," says Bearman.

    But here's where proponents of the liberal approach can stop feeling
    smug. Because despite many people's unquestioning assumption that
    comprehensive sex education is the best way to reduce teenage
    pregnancy, there is actually little good-quality evidence backing this

    One of the problems in carrying out randomised controlled trials in
    this area is the question of who should be used as the control group.
    Most schools now have some form of sex education in place, however
    rudimentary, and it would be unethical to take this away from some
    children to create the control group. Instead researchers have tended
    to compare standard sex education with new initiatives specially
    designed to reduce pregnancy rates. But the results have been
    unimpressive. A systematic review in 2002 of 26 such studies showed
    that not one of them improved the use of birth control or reduced the
    teenage pregnancy rate (British Medical Journal, vol 324, p 1426).

    But in the past few years, a handful of randomised controlled trials
    have been published showing that some carefully designed sex education
    programmes do appear to work. One of the most effective is the Carrera
    Adolescent Pregnancy Prevention Program, aimed at 13 to 15-year-olds
    in a poor area of New York (Perspectives on Sexual and Reproductive
    Health, vol 34, p 244). Abstinence is mentioned during the programme,
    but most of the emphasis is on contraception. A three-year study
    showed that the pregnancy rate of teenage girls who took the programme
    was less than half the rate of those who didn't. Analysis showed this
    was due to both greater condom use and delayed onset of sex.

    Why should these programmes be any different? As well as lasting
    longer, they were, says Kirby, "interactive and personalised, not just
    abstract facts". The Carrera programme, for example, not only covered
    sexual behaviour, it tackled the social disadvantages that lead to
    teenage pregnancy. Along with information on and free access to
    contraceptives, it involved intensive youth work such as sports, job
    clubs and homework help.

    Most UK sex education programmes seem half-hearted in comparison,
    providing the bare biological facts, perhaps alongside a demonstration
    of how to put a condom on a cucumber. "It's something I feel quite
    angry about," says Michael Adler, a former STD physician at University
    College London Hospital. In his job he saw many casualties of unsafe
    sex. "We're failing young people right at the beginning," he says.

    Unfortunately policy makers have recently lost a good source of
    information about what works and what doesn't. The US Centers for
    Disease Control and Prevention (CDC) in Atlanta, Georgia, commissioned
    a panel of external experts to carry out a rigorous review of various
    sex education programmes. The panel identified five strategies that
    were successful in reducing the rate of teenage pregnancy, all based
    on comprehensive sex education, and the details were posted on the
    organisation's website. But in 2002 that information disappeared and
    the CDC will no longer release it.

    According to the CDC press office, the review programme is being
    "re-evaluated". But sceptics fear it has been dumped because its
    conclusions don't fit with the Bush's administration's views. "They
    were inconsistent with the ideology to which this administration
    adheres," says Bill Smith of the Sexuality Information and Education
    Council of the United States, a liberal sex education advocacy group
    based in New York.

    What of the study that made the newspaper headlines in the UK last
    year, showing that contraception provision is linked with higher STD
    rates? Perhaps it should not really be taken as a damning indictment
    of the liberal approach. The study looked at National Health Service
    family planning clinics, not school-based comprehensive sex education.
    Simply doling out condoms without tackling the wider issues is
    unlikely to have much impact. Anyway, should the correlation between
    sex clinics and STD levels really be so surprising? "Has it occurred
    to [David Paton] that they put more services in areas with high
    rates?" asks Roger Ingham.

    In fact, amid all the scare stories, the average age when a person
    first has sex now appears to be levelling out at around 17 in the US
    and 16 in the UK. And although rates of STDs are on the increase in
    the UK, teenage pregnancy and birth rates are on a downward trend, as
    they have been in most developed countries for several years. A report
    from the Alan Guttmacher Institute, a reproductive health research
    group in New York, concludes this is due to factors such as the rise
    of careers for women, and the increasing importance of education and
    training (Family Planning Perspectives, vol 32, p 14). Perhaps it is
    unsurprising, then, that it is among society's lowest income groups
    that teen pregnancy rates are highest.

    In the face of such complex societal forces, those who try to
    influence teenagers' behaviour on a day-to-day basis undoubtedly have
    a tough job on their hands. There may be no single solution. More
    research is needed to produce detailed information on which kind of
    sex education programmes work best, and in which contexts.

    One approach is to involve older teenagers, on the premise that
    14-year-olds may be more likely to listen to 18-year-olds than people
    of their parents' generation. Since having her son, Lynsey Tullin has
    started working for Brook, a young people's sexual health charity, to
    ensure that today's teenagers are more savvy about sex. "We talk the
    same language," she says.

    A tactic that she finds hits home is to describe new parenthood in all
    its gory details - the nappies, the lack of sleep, a social life in
    tatters. "We run workshops about being parents, telling them what we
    went through," she says. "It's a shock."

Different approaches to teenage sexuality

    Comprehensive sex education

    Provides explicit information about contraception, sexuality and
    sexual health

    Abstinence-only approach

    Teaches that the only place for sex is within marriage, and the only
    certain way to avoid pregnancy and STDs is abstinence. Does not teach
    about contraception


    Promotes abstinence as the best choice, but provides varying degrees
    of information on contraception in case teens do become sexually

Heads I win, tails you lose

    LOOK at any abstinence-only literature, and you'll read that this is
    the only certain way to prevent pregnancy and avoid catching a
    sexually transmitted disease (STD). "Abstinence. Failure rate 0 per
    cent," is the claim on one pro-abstinence website.

    But does this make sense? The most important measure of any method of
    preventing pregnancy and STDs is not its ideal effectiveness, but its
    "use effectiveness" - how successful it is in the real, sometimes
    messy, world of sex. Condoms, for instance, have a 97 per cent success
    rate at preventing pregnancy if used correctly, but have an estimated
    use-effectiveness of 86 per cent, due to problems such as tearing or
    slipping. If people who intend to use condoms but never get as far as
    opening the pack are included, some studies suggest the
    use-effectiveness of condoms could be as low as 30 per cent - the sort
    of figure abstinence fans shout from the rooftops.

    What about applying the same real-world rules to abstinence?
    Unfortunately there are no studies detailing the use-effectiveness of
    abstinence in preventing pregnancy, but it is highly unlikely to be
    100 per cent, as commonly claimed by its proponents. Their reasoning
    goes like this: individuals who set out to remain abstinent but
    succumb to temptation and have sex are no longer seen as abstinence
    "users". And those who become pregnant may even be marked up as a
    failure for the contraception strategy if, say, they attempted to use
    a condom but bungled it.

    Abstinence campaigners are very vocal about the failings of
    contraception. But is it perhaps time to own up about the failure rate
    of abstinence?

Teenagers special: Bully boys
      * 05 March 2005
      * Clare Wilson

    LAST year the UK pop music station BBC Radio 1 mounted a "Beat
    Bullying" campaign, and over six weeks it was flooded with more than 1
    million requests for its free "Beat Bullying" wristbands. As it
    struggled to meet demand, a thriving market opened up on eBay for
    these blue plastic bracelets. Bullying, it seems, struck a nerve -
    which is hardly surprising, given that an estimated 1 in 5 secondary
    schoolchildren in the UK has been bullied.

    Most efforts to tackle the problem involve working with the
    perpetrators as well as their victims. Teachers may be urged to help
    bullies recognise and modify their behaviour.

    Bullies, it is commonly believed, often come from unaffectionate or
    violent families, and may have poor social skills and low self-esteem.
    "Particularly in America, the traditional view is that [bullies] are
    malfunctioning," says Peter Smith, a psychologist at Goldsmiths
    College, University of London, who has advised the UK government on
    how best to tackle bullying.

    But could this view be wrong? Far from being the result of a damaged
    psyche, could bullying be a successful social strategy - albeit one
    that is very unpleasant for people on the receiving end? Over the past
    few years, some psychologists, including Smith, have started to think
    so. They believe that at least some kinds of bullying boost the status
    of the bully among his or her peers.

    Several studies by Anthony Pellegrini, an evolutionary developmental
    psychologist at the University of Minnesota, support this theory. In
    one study published in 2003, he asked a group of 138 schoolchildren
    aged between 12 and 14 to say how aggressive their classmates were,
    both physically and psychologically. On a separate scale, they had to
    say which members of the opposite sex they would ask to a party
    (Journal of Experimental Child Psychology, vol 85, p 257).

    Those most likely to get an invite were boys who were physically
    aggressive and girls who were psychologically so. "Boys have high
    status with their male peers if they're bullies, and girls like them,"
    says Pellegrini.

    If it turns out to be true that bullying raises the perpetrator's
    social status, trying to change bullies' behaviour by boosting social
    skills and self-esteem may not work. "Some bullies, at least, are
    socially skilled," says Smith. "These skills have a function, which is
    to enhance your status in a competitive peer group."
Teenagers special: Live now, pay later
      * 05 March 2005

    In the west, some of the biggest threats to teenagers long-term health
    stem from bad habits such as eating unhealthily and smoking. Policy
    makers are also paying growing attention to adolescents' mental

    Fewer than 20 per cent of 13-to-15-year-olds in England eat the
    recommended five portions of fruit and vegetables a day

    American teenagers spend an average of 3 to 4 hours a day watching TV

    In Australia, 20 to 25 per cent of under-17-year-olds are overweight
    or obese

    Almost a quarter of 15 and 16-year-olds in the UK smoke regularly

    Some estimates suggest that up to 1 in 5 adolescents have some form of
    psychological problem, ranging from eating disorders to depression or

    In England 11 per cent of 11-to-15-year-olds have used drugs in the
    last month.

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