Friday 8 May 2009

Notes from a young science

50 Genetics Ideas You Really Need to Know, by Mark Henderson

Last time I volunteered to review a book for Culture Wars on evolution and genetics, I was given Steve Fuller’s ‘unconventional’ pro-Intelligent Design screed Dissent Over Descent, a densely written and ultimately barmy sociological critique of modern biology. So it was a pleasure to be given The Times science editor Mark Henderson’s clearly written, interesting, and above all scientifically orthodox 50 Genetics Ideas You Really Need to Know.

Published by Quercus, it is part of a series of books introducing other often intimidating subjects such as physics, maths and philosophy. It’s pitched at a non-expert level, divided into 50 short essays, each detailing a particular aspect of genetic theory or technology, and accompanied by easy to understand diagrams and text boxes. This broad sweep gives an overview of an entire branch of science that is rarely available from more area specific popular science books. Starting with the basics of inheritance, replication and evolution, the book gives an idea of the history of this young science and its discoveries, covering many recent developments and looking into the multiple cans of worms that genetics has opened along the way.

One of the ideas that Henderson puts across very clearly is the fact that most genes don’t, on their own, have a massive impact on the final outcome of human beings’ characteristics, or phenotype. Most genes that the public hears about, such as that for Huntingdon’s disease, or the BRCA genes that predispose women to breast cancer, have a very large effect; in the case of Huntingdon’s, if you carry the gene, you will develop the disease. But the majority of genetic effects are far more subtle, increasing the likelihood of a particular outcome, such as tall height or heart disease, by only 10 or 20%, generally working in concert with other genes. The technology, computing power, and genomic databases large enough to find these very slight statistical effects, through so called ‘genome wide association studies’, has only existed for literally the last three years or so.

Genetic effects are also mediated by the environment as well, meaning that the traditional ‘gene for x’ terms in which people often think are outdated. The cell itself can control the expression of genes, through regulating RNA molecules encoded by ‘junk’ DNA, or through epigenetics – changes in how a gene is ‘packaged up’ and tagged, which can lead to weird ‘Lamarkian’ effects, whereby things like grandparental diet can have an effect on your health. The book covers practically every cutting edge area, from Craig Venter’s attempts to create new life with ‘synthetic biology’, to the wacky world of ‘Evo-Devo’, the study of the history of evolution through embyro genetics; a line of research that has discovered the genes underlying a common system of body patterning in everything from fruit flies and flatworms to human beings, and is honestly much more interesting than I have just made it sound.

Henderson also admirably deals with the various ‘hot potatoes’ that the debates around genetics have thrown up. His chapter on the genetics of race covers similar ground to the argument advanced in Kenan Malik’s Strange Fruit, that the genetic variation that does exist between human populations doesn’t form anything that can coherently be called ‘races’, and that the variety there is probably isn’t worth worrying about. Not that this troubled 19th century eugenicists and ‘Social Darwinists’, who used the emerging science to support their reactionary social theories; a taint that has been hard to remove.

The chequered history of the science is reflected in some of the colourful characters who practiced it. James Watson’s inflammatory comments on racial inequality come in a long line of such controversy; practically all the leading lights of 20th century British genetics were either crypto-fascists (such as RA Fisher, with a pre-war predilection for eugenics and Norse mythology) or fully paid up Communists (such as JBS Haldane who had to pull contortions as the Soviet Union adopted the unscientific ‘Lysenkoism’). Henderson’s book adds some more information that I at least hadn’t been aware of: American geneticist Herman Muller (he of ‘Muller’s Ratchet’ for the biologists amongst you) moved to the USSR in the 1930s to support socialism, then had to flee to avoid the Gulag as Darwinism was declared ‘bourgeois’; and Nobel prize winner Linus Pauling was blacklisted under McCarthyism, obstructing his research and enabling Crick and Watson to beat him to the structure of DNA.

Other more contemporary areas of contention include genetic testing, with largely unregulated commercial tests available over the internet which are seen by many as scientifically dodgy, charging punters large sums for the ‘scientific’ advice that their genes tell them they should eat more vegetables. On the other hand, this sort of testing is enabling exciting advances towards what is known as ‘personalised medicine’ – where those predisposed to respond well to a particular treatment, or to develop side effects, can be identified before they are given the drugs.

And for a book ostensibly about molecular biology, there is quite a lot on the big philosophical questions of human nature. Henderson rehearses the ‘blank slate’ battle of the 1970s and 80s, between socio-biologists and evolutionary psychologists who advocated biological investigation of human nature and society, and their ‘left wing’ opponents who had a more cultural and sociological understanding. This was a particularly bad-tempered argument in a scientific world used to heated disagreement - besides ad hominem attacks, socio-biologist EO Wilson was doused with water by students who objected to his ‘fascist’ theories.

The argument has been largely resolved, with victory for the non-blank-slaters, as evidence has arisen of genetic involvement in aggression, mood, mental illness, and perhaps even intelligence (although with a heavy element of ‘nurture’ involvement). The blank-slaters were condemned too by their slightly hysterical tone, which tried to put certain areas outside of legitimate scientific research, and their often equally deterministic ideas of cultural identity, criticised by Henderson as ‘just as inimical to human freedom’ as the crudest socio-biology.

But despite their faults, their beliefs were based on an understanding that human society has changed and can continue to change historically - the massive shifts of human social relations between hunter gatherer and feudal or industrial society are so great, and so evolutionarily recent, that knowledge genetics doesn’t really add much to our understanding of these developments. The defeat of the sociological understanding of humanity reflected the broader defeat of left-wing attempts to change the world; a defeat that has taken much of the heat out of the nature-nurture argument. The perhaps slightly boring answer, that there is a ‘bit of both’ nature and nurture involved in human existence, still hasn’t answered the question where the influence of each begins and ends, and more importantly, how we might control them both.

But wherever these debates might end up going in coming years, Henderson’s book, with its wide scientific scope and easy comprehensibility, is a good place to begin.


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