Teenagers: A Natural History by David Bainbridge
Bill Thompson gets down with the kids
In Teenagers Cambridge University vet David Bainbridge tries to convince us that the teenage years are not simply ones of gawkiness, spots and dangerous sexual and chemical experimentation but should be seen as the most exciting time of our lives, the greatest achievement of human evolution, and the point where all that is special about our species comes into play.
He almost pulls it off, as he describes the complex interplay of hormones and brain activity that kicks off puberty, the radical pruning of the brain’s circuitry as we mature and the tensions that inevitably arise when physiological changes that apparently evolved to serve the needs of all primates take place in city-living homo sapiens.
The core of Bainbridge’s argument is that adolescence is the centrepiece of the human life-plan and that the carefully staged sequence of developmental changes he describes evolved to give humans time to become self-aware adults able to raise and nurture their young.
In order to convince us of this he covers a vast range of material, from the low-level changes in hormone production and brain anatomy that mark the end of childhood to the way friendship circles promote – and can damage – self-esteem and why teenage pregnancy may once have conferred evolutionary advantage.
Fortunately Bainbridge is a veterinary anatomist at Cambridge University and he clearly knows his science. This, along with an enviably lucid writing style, enables him to explain brain structure and physiology in an accessible way, dealing effectively with current models of development for non-scientific readers while not inadvertently patronising those who already know where the hypothalamus is located.
However, when he gets away from straight science he can be irritatingly informal, and passages where everything is “fizzing”, “exuberant” and “sexy” become grating, as if he is not sure whether he is writing for parents, interested adults or the teens themselves. The result, in chapters dealing with relationships, drugs and sex, is unconvincing either as an explanation of what is going on or as a guide for parents or children.
A more fundamental problem emerges when Bainbridge tries to explain why things are as they are. When he is concerned with anatomy he is scrupulously careful, pointing out that the fact that Broca’s and Wernicke’s areas, brain areas concerned with speech and language, become linked during adolescence is not necessarily the reason why late teenagers are more articulate since mere correlation is not proof.
Yet he repeatedly invokes hypotheses from evolutionary biology, littering the book with “just-so” stories that carry as much explanatory power as Rudyard Kipling’s tale of how the elephant got its trunk. We hear that girls mature earlier so that they can be traded between tribes while boys must remain unthreatening to adult males, that language evolved so that home-bound women could communicate with each other, and that risk-taking is “built into” human adolescence: tales whose plausibility relies more on wish-fulfilment than on science.
The book is strangely silent on one of the biggest shifts in teenage existence at the moment: the impact of new audio-visual technologies like computer games or the use of the internet. If, as Bainbridge claims, we are over-stressing teenage brains by asking them to cope with a world very different from the one they evolved to survive in, surely the PlayStation deserves a mention.
More significantly, there is also no attempt to engage with the broader social, political and even religious context within which teenagers have to manage the transition from childhood to adulthood. The teenagers in this book are western and secular.
Even so, the book offers an illuminating exploration of adolescence, and I admit that knowing that my son’s brain is slowly replacing the old tegmentum-accumbens reward-seeking system with a tegmental-accumbens-prefrontal pathway that allows emotions to be more controlled by intellect does actually help me have more sympathy for his moods and apparently chaotic behaviour.
Teenagers: A Natural History is published by Portobello