## Articles

*On the origin of species*, but also 200 years since the birth of its author, Charles Darwin. At the heart of Darwin's theory of evolution lies a beautifully simple mathematical object: the evolutionary tree. In this article we look at how maths is used to reconstruct and understand it.

*string theory*have nudged their way into public consciousness. It's a theory of everything in which everything's made of strings — or something like that. But why strings? What do they do? Where did the idea come from and why do we need such a theory?

**David Berman**has an equation-free introduction for beginners.

**Rob Eastaway**and

**John Haigh**find chance in church and work out the odds.

*any*tilings based on fiveness?

**Craig Kaplan**takes us through the five-fold tiling problem and uncovers some interesting designs in the process.

**Chris Sangwin**takes us through excerpts of Euler's algebra text book and finds that modern teaching could have something to learn from Euler's methods.

**Chris Sangwin**tells you how to make your own set of

*Napier's bones*and perform mathemagic with an interactive checker board.