In 1998, computer scientist Ehud Shapiro returned to the Weizmann Institute in Rehovot, Israel, as a group leader after a five‐year break as a software entrepreneur. At the peak of the Internet boom, it would have been easy to find an exciting topic to pursue in computer science. Instead, Shapiro became interested in the origin of life and began to train himself in molecular biology, which eventually sparked his idea to build computers from biological molecules. His team first constructed a molecular Turing machine based on DNA, restriction nuclease and ligase to perform simple computations (Benenson et al , 2001), soon followed by a more sophisticated system that performs stochastic computations using mRNA molecules as input (Benenson et al , 2004). What seems merely to be the intellectual interest of an Israeli computer scientist—using biological compounds and systems to create logical circuits—has in fact become the hottest area in the biological sciences: synthetic biology. Other engineers are also dropping their soldering guns for micropipettes to rewire genes and genomes with the aim of reprogramming living organisms. “Synthetic biology is the other side of the coin of systems biology,” commented Victor de Lorenzo, Vice Director of the National Centre of Biotechnology in Madrid, Spain. “What you want is to create or recreate systems that have some properties of life from engineering principles.” This includes a range of techniques from recombinant cloning, to synthesizing genomes de novo , to creating completely new entities such as Shapiro's artificial systems. However, more interesting than the technology itself is the ability to create artificial metabolic and regulatory pathways and to test their viability in living systems. It allows scientists to probe the complexity of an organism's innards and thus derive further insights into how cells work. As George Church, Professor of Genetics at Harvard Medical School …