Genes - the 'book' of life?
60 years of DNA The simple story we're told about how genes are the 'blueprint' or 'book' of life is "misleading" and "distorted".
That's the provocative view of science writer Phillip Ball who has written a commentary in this week's Nature.
Sixty years ago today, Francis Crick and James Watson published details of the double helix molecular structure of DNA.
But Ball argues we still don't know how evolution works at the molecular level.
"While specialists debate what the latest [genomics] findings mean, the rhetoric of popular discussions of DNA, genomics and evolution remains largely unchanged, and the public continues to be fed assurances that DNA is as solipsistic a blueprint as ever," says Ball.
"[T]he usual tidy tale of how 'DNA makes RNA makes protein' is sanitised to the point of distortion."
But his commentary has raised the hackles of some Australian experts, who defend what has become known as the central dogma of molecular biology.
Some years after the landmark paper describing the double helix structure was published in Nature, Crick articulated the basic idea that 'DNA makes RNA, which makes protein', which ultimately produces an organism's 'observable traits'.
But Ball says this narrative is oversimplified.
"Sixty years on [from the double helix], the very definition of 'gene' is hotly debated," he writes.
"We do not know what most of our DNA does, nor how, or to what extent it governs traits."
Ball says "difficult questions" are raised by a number of discoveries. These discoveries include the fact that only a tiny fraction of the genome produces protein; that chemical modification of DNA can affect expression of genes; and that genes work together in networks.
"When the structure of DNA was first deduced, it seemed to supply the final part of a beautiful puzzle. The simplicity of that picture has proved too alluring. For the jubilee we should do DNA a favour and lift some of the awesome responsibility for life's complexity from its shoulders," he concludes.
A complex story
But Australian expert in haemophilia and obesity genetics, Professor Merlin Crossley disagrees with Ball's view.
"I think the models for evolution work well, our understanding of genes work well," says Crossley, who is Dean of Science at the University of New South Wales in Sydney.
"Biology has always been more complicated, more untidy and often more wasteful than we imagined," says Crossley, who argues much of the human genome is made up of parasitic retroviruses that aren't much use to humans.
Crossely says the collection of vast amounts of genomic data in recent years has revealed things are not as simple as we might have thought before.
But he sees no "looming paradigm shift".
"I don't think it's a tell tale sign that we've got things wrong."
Professor Simon Foote, who studies the genetic control of susceptibility to diseases such as malaria, agrees molecular genetics is "hideously complicated", but also rejects Ball's conclusion.
"I think it's largely rubbish," he says.
"The central dogma is not wrong," says Foote, Dean of the Australian School of Advanced Medicine at Macquarie University.
"No matter how complex things are, the central flow of information is still the same. What is complex is the regulation of that."
Like Crossley, Foote fully supports DNA metaphors such as the "blueprint" or "book" of life.
He says while there is much to understand about evolution, he has no doubt it is encoded in the genome.
Foote says humans and chimps have a 99 per cent similarity in protein-encoding genes, but quite different DNA sequences involved in determining whether and how those genes are expressed.
"At least changes in speciation are probably due to changes in regulation of DNA," says Foote.
Foote agrees simplistic communication of genetics, and communication based on "hype" or "promise not fact", has led to false expectations about what can be delivered by genomics research.
"There was this concept of one gene, one disease, but the Human Genome Project really threw that out the window," says Foote.
"There are 60 genes involved in multiple sclerosis, each contributing a small fraction, probably interacting with each other, probably interacting with the environment."
He says rather than being and end in itself, the Human Genome Project is a useful tool for exploring biology in all its complexity.
Like Crossley, Foote says the complexity of genetics is not generally passed on to the community.
But neither should it, says Dr Paul Griffiths, a professor of philosophy of science at the University of Sydney.
A gene means many things
Griffiths, who is co-author of a new book called Genetics and Philosophy, says a gene is understood to mean different things by different people.
For example, he says, a molecular biologist will use the term to describe a sequence that codes for a product, such as protein or RNA.
But a gene can also be defined as any part of the DNA that affects a phenotype, says Griffiths, and this includes regions of the DNA that don't produce anything but still regulate gene expression.
Griffiths says this more "mendelian" definition of the gene is useful, for example, to evolutionary geneticists, who build models linking genomic change to evolution.
This definition is also useful in communicating genetics to the public, he says.
While simplistic communication about genetics can be used to hype the importance of research, and it can encourage the impression that genes determine everything, he does not believe the answer is to communicate more complexity.
Broadly speaking, the central dogma still holds, says Griffith, and simple statements based on it just need to be balanced with other similarly simple but still roughly true statements such as: "Every feature of the organism is a result of the interaction between its genes and its environment."
Science communication academic, Dr Joan Leach of the University of Queensland, agrees the average member of the public is not going to be that interested in the complexity of genetics, unless its relevant to an issue that they care about.
"Is there a problem that we need to know about here?" asks Leach, in response to Ball's article.
"There are dangers in telling the simple story, but he hasn't spelt out the advantages of embracing complexity in public communication."