A group of engineers from MIT have created analog calculators out of living cells, according to a paper published online in Nature yesterday. By tweaking the genes of bacterial cells, the researchers were able to create circuits that can perform calculations - including division, multiplication, logarithms and square roots - in a much more efficient way than many existing biocomputers.

Pretty much anything can be a computer, if it can compute logical functions, store data, and transmit information - even living cells. A team at Stanford University has accomplished one of the the final tasks necessary to turn cells into working computers: They've created a biological transistor, called a transcriptor, that uses DNA and RNA instead of electrons and responds to logical functions.

Not all computers are made of silicon. By definition, a computer is anything that processes data, performs calculations, or uses so-called logic gates to turn inputs (for example, 1s and 0s in binary code) into outputs. And now, a small international community of scientists is working to expand the realm of computers to include cells, animals, and other living organisms. Some of their experiments are highly theoretical; others represent the first steps toward usable biological computers. All are attempts to make life perform work now done by chips and circuit boards.