There can be no one unifying theory, writes Prof Jonathan Bard, while Nicholas Maxwell looks to the role of purposive actions and Pete Bibby says the fittest theory will survive
Stephen Buranyi misses some key points in his article (Do we need a new theory of evolution?, 28 June). Darwin saw novel speciation as resulting from natural selection acting on anatomical variants, but that simple skeleton needed fleshing out. It took a century of research, for example, for us to understand the importance of inheritance in very small populations if novel variants were to become predominant.
The major problems in understanding evolutionary change today are as follows. First, working out how anatomical variants form – and this is hard because we don’t yet have a full understanding of how normal embryology works (evolution, it has been claimed, is development gone wrong) and can only rarely recognise a favourable mutation. Second, unpicking the generally opaque processes of selection (there are at least four independent reasons why zebra stripes would be favoured). Third, understanding why substantial evolutionary change seems so slow, albeit that this is what the fossil record demonstrates. This is the topic that excites the community that Buranyi discusses, even though modern molecular genetics and systems biology show that heritable novelties can form more rapidly than they realise.
