Leonardo da Vinci, Robert Hooke and Charles Darwin, to name but a few influential historic scientific figures, each made significant contributions to many areas of science — from optics and astrophysics to evolutionary biology and aviation. So, why is it that interdisciplinary research is so hotly debated today?

Although most will agree that interdisciplinary approaches are essential for a quantitative, holistic understanding of biology, there are perceived barriers and problems that can inhibit interdisciplinary activity, as John McCarthy discusses on page 933. However, these could be overcome by new research environments — for example, theme-orientated interdisciplinary research institutes. Suitable training for students is also essential, as are partnerships between academia, governments, funding agencies and industry to create successful research strategies.

Also in this issue is a Timeline article by Yilun Liu and Stephen C. West (page 937) on the Holliday junction. This now-famous, cross-stranded DNA structure is known to be a central intermediate in the process of recombination, as was first proposed by Robin Holliday. Forty years on, the importance of the Holliday model is highlighted by the fact that, rather than having been replaced, it has evolved over time.

Finally, this month's issue is accompanied by a poster by John C. Reed and Ziwei Huang, which depicts the main apoptosis pathways and provides an overview of the key chemical targets and drug leads that are now being developed for therapeutic purposes. The poster, which is a collaboration with Nature Reviews Drug Discovery and has been produced with generous financial support from Merck Research Laboratories — Boston, will be freely available online until the end of April 2005 (http://www.nature.com/reviews/poster/apoptosis).