the nature of science (again)

The new Science curriculum has the 'nature of science' right up there at the top. And why? Because it's so important for people to learn, not just science facts and concepts, but also about what science is: how it's done, the tools and methods scientists use, how they communicate, its history, & how science is a part of everyday life.

I was reading a paper recently that made me think I'd revisit this topic yet again. It's a paper looking at teaching about evolution and the nature of science (Farber, 2003), which – as you've probably guessed by now! – is a subject dear to my heart. The paper resonated with me because it said something that I feel very strongly & try to achieve in teaching my students at Waikato: there's probably little value in simply teaching a whole body of facts about evolution; far better to look at how Darwin's theory developed and what this can tell us about the nature of science and how science operates. What are some of the key messages?

Science is dynamic in nature – it's not a fixed set of facts & doesn't simply represent the 'truth' about the natural world, but changes through time as new data are collected. Darwin was alive at a time when scientists were redefining a whole range of concepts ('species', for one). Scientists are constantly coming up with new questions, new interpretations, new opinions. And because of this, it is eventually self-correcting. A good (non-evolutionary) example here is the discovery that most stomach ulcers are caused by infection with the bacterium Helicobacter pylori. When this idea was first proposed, biologists laughed at it. But the scientists concerned persisted and demonstrated – by infecting themselves, among other things – that the infection/ulcer link existed. The weight of evidence convinced the scientific community – and the scientists who made the discovery received a Nobel prize.

Farber also points out that science has several levels of generality: facts, hypotheses, laws, and theories – and that we do need to know where a particular claim or bit of information fits if we're to evaluate it properly. He comments that we can use observation for most facts and experiments for most hypotheses. Theories are evaluated on how well they explain and relate, and therefore are not "proved" or "disproved". They are inherently open-ended and always have "problems" to be solved, which is a strength, not a weakness (my emphasis). Remembering this is so important when we're talking about evolution – which is, after all, the underpinning of all of modern biology. As Theodosius Dobzhansky once said (1973), Nothing in biology makes sense except in the light of evolution.

Science also has levels of certainty – there are some things which have been repeatedly and extensively confirmed through observation and experiment e.g. Mendel's laws of inheritance. In contrast, Farber comments that the Big Bang theory, while it explains a great deal of the data we have on the origin and development of the universe, could still conceiveably be replaced. And the theory of evolution? Well, there's an enormous amount of evidence that life on Earth has changed over time. But our understanding of the evolution of particular branches of life's tree – our own included – is still being developed as new information comes to hand.

How do scientists 'do' science? What's the scientific method? There's actually no one 'scientific method' – scientists use different tools for different jobs. They may use experiments e.g. Kettlewell's famous (& often misrepresented!) work on peppered moths in the UK, or studies of the mating preferences of Drosophila reared on different foods. They may rely on observation and comparison – the role of host switching in indigobird evolution, for example, or the use of molecular biology, palaeontology, or embryology in teasing out evolutionary histories and relationships. And it may involve intellectual creativity – seen in the way Darwin drew together observations and inferences in developing the concept of natural selection as a key agent of evolution.

And finally – you can't isolate science from the social/cultural context in which it's done. Scientists don't stand apart from society, we are part of it & our views and perspectives are shaped by it. Darwin lived during the Industrial Revolution, at a time when individuals and institutions in Europe were getting their hands on huge amounts of geological and biological material from around the globe – and examination of this material generated a particular set of scientific questions. At a different time, in a different society, Darwin might well have phrased his ideas differently.

Biology is… a quest towards understanding, one that is ever changing and one that has roots not only in the phenomena that we observe, but in the human world that shapes our concerns and questions (Farber, 2003).


T. Dobzhansky (1973) Nothing in biology makes sense except in the light of evolution. The American Biology Teacher 35: 125-129

P. Farber (2003) Teaching evolution and the nature of science. The American Biology Teacher 65: 347-354


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