In many ways, living things are organic machines, and the instructions for how they operate are contained in the DNA. So perhaps it's not surprising that DNA ought to be able to perform simple arithmetic calculations, much like computers. That doesn't mean it's not a monumental breakthrough for scientists to create an analog circuit out of DNA that can act like a calculator.

A team of researchers from Duke University has done exactly that. They have created strands of synthetic DNA that, when mixed together in a test tube in the right concentrations, form an analog circuit that can add, subtract and multiply, reports

What makes this breakthrough particularly interesting is that it involves an analog DNA circuit rather than a digital one. Digital circuits encode information as a sequence of zeroes and ones, and while this has its advantages in the world of computing at large, it has some disadvantages if you want to create computers from genetic material. For one, digital DNA circuits require more strands of DNA than analog ones. Also, if you want to calculate values that don't lend themselves to simple on-off, all-or-none values — which is the case for many organic processes — analog is the way to go.

The circuit made by the Duke researchers is still pretty basic. Its test tube calculations can take hours, even for simple equations. But it's a start.

"We can do some limited computing, but we can't even begin to think of competing with modern-day PCs or other conventional computing devices," admitted John Reif, team leader on the study.

Processing speed isn't necessarily the goal, though. Even slow computers made from DNA offer advantages over silicon-based computers. For instance, DNA circuits can function in wet environments. They can also be far tinier compared to electronic circuits. After all, DNA fits inside the nucleus of a cell.

Imagine if a DNA-based calculator could be inserted directly into the bloodstream or at the cellular level to make more accurate medical measurements. With further development, that's the future of technology like this.

"Even very simple DNA computing could still have huge impacts in medicine or science," explained Reif.