Almost every couple of months there is news that another important species has been cloned through somatic cell nuclear transfer (SCNT). The most recent cab off the rank is the rat (see Highlight on page 853) — a surprisingly late appearance for such an important model organism.

However, all has not been plain sailing for cloning researchers. As Ian Wilmut and colleagues highlight in their Review on page 855, we have an enormous amount to learn about the genetic and epigenetic factors that cause most cloning attempts to fail. If we could grasp exactly which of the factors that are peculiar to SCNT cause clone failure, we would be closer to realizing the enormous therapeutic potential that the non-reproductive cloning of humans offers.

The emerging potential of a much older approach is the subject of the Review by George Roderick and Maria Navajas on page 889. Genetic studies of biological control strategies are providing useful tests of evolutionary theory, as well as indications of the potential impact of the release of genetically modified organisms (GMOs). This is good, because given the battering that GM crops have taken in the United Kingdom media recently (see In The News on page 852) the more pertinent information we can gather on the impact of GMOs the better.

Finally in this issue, for the second successive month, we introduce a new type of Perspective article. This month's addition, Guidelines, is designed to clearly outline how to approach a particular research area. By their very nature, such articles will often represent the consensus view of a particular community; in this case, that of members of the Complex Trait Consortium on the definition and identification of quantitative trait loci.