On nature vs nurture
The relative contribution of our genes and environment to our behaviour is a long-running debate. British science writer Matt Ridley, author of Nature via Nurture, here gives his perspective. Nerissa Hannink reports.
Ridley presented key insights on the question during a recent talk at the University of Melbourne. Here he responds to questions put forth by the University of Melbourne Voice newspaper.
Question: Why has the debate over nature vs nurture existed for so long?
Answer: People are interested in the debate as they are curious about themselves, about their children, and unlike nuclear physics, it’s something they can grapple with as an amateur.
The debate has also persisted as it’s so difficult to resolve. We know that we come with innate characteristics and that our environment influences us, but actual explanations are hard to come by.
I find it hard to believe that anyone who’s had two children does not believe in the influence of genes. The second child comes into the same environment as the first, but has an entirely different approach to the world. And yet there are obvious similarities too, because they have shared genes. We actually ought to be more similar, but because our genes are scrambled in sexual reproduction we get a unique deal of the cards.
Question: Do you think the term ‘Nature via nurture’ has resolved much of the debate?
Answer: I’m hoping that the term will be a helpful slogan under which to recognise that there is a new way of understanding the issue through figuring out how genes work. Because, nature is not the opposite of nurture, and genes are at the mercy of our experiences.
Genes can be determinist, for example if they give you blue eyes (there’s not much you can do about it) but so can experiences.
The sequencing of the human genome has suggested a new hypothesis: that animal evolution usually works not by inventing new protein-coding genes (this appears to be commoner in plants) but in fact by altering the expression of pre-existing genes.
Question: What would be your favourite example to illustrate nature via nurture?
Answer: My favourite is a study from Dunedin, New Zealand, conducted between 1972 and 1973. Researcher Terrie Moffitt and her colleagues investigated differences in the promoter (or ‘switch’) region of the brain’s serotonin transporter gene which can affect the way people react to stressful life events – things like divorce or bereavement. (Serotonin is a neurotransmitter, a chemical ‘messenger’ that allows communication between nerve cells.)
The study found that people with one or two copies of the short version of the serotonin promoter showed more symptoms of depression following at least three stressful life events than people with two copies of the long version. For one or two events there was no difference.
In other words, your genome does not make you depressed, but makes you more susceptible to environmental pressures; in this case it makes you more likely to be depressed when you suffer several external setbacks. And that has to be how things like intelligence are determined. A clever person is not born clever, they’re born more able to take in teaching, they’re born capable of learning.
So it’s not a gene for intelligence, it’s a gene for learning. A tennis player or scholar may not have been much better at tennis or study to start with, but was innately drawn to doing a lot of tennis or study and practice that made him or her perfect. So the nature sought out the nurture.
Question: You began your career with a PhD in Zoology and now write books popularising science, how important do you think it is for people to understand science?
Answer: I write about science and I just love telling stories from this incredible adventure. If you take just genetics, which is what I’ve mostly been writing about, a few years ago we became the first creature to read our own recipe. Who would not want to be engaged in that debate? Who would not to have a chance to understand what we’re discovering for the very first time?
We’re shedding light on corners of not only human nature, but also the evolution of life on this planet, how animals are related, and when the whole thing got started.
Take the discovery that there was a universal genetic code. That didn’t have to be true. It might have been that plants had one code and animals had another, but no, both share a universal genetic code and that means we all have the same ancestor, what an amazing thing to know. How thrilled Aristotle would have been to know that, but never got the chance, so how incredibly lucky we are to be alive today.
Question: Would you like your own genome sequenced?
Answer: I’d happily have my genome sequenced, and one day I hope to. It costs of the order of a million dollars now, but the way it’s going it’s bound to get cheaper and I think it would be fascinating. But there are genes that I’d be very cautious about looking at, like do I really want to know my propensity for Alzheimer’s? Although I think I can already guess.
Matt Ridley is the author of The Red Queen: Sex and the Evolution of Human Nature, The Origins of Virtue: Human Instincts and the Evolution of Cooperation and Genome: The Autobiography of a Species in 23 Chapters.