From Micro-Soft to Bio-Soft: Computing With DNA

The notion of computing seems nowadays to be so synonymous with computers, that we often seem to forget that electronic computers are relatively new players on the world stage, [31]. Indeed, a brief look at the history of humanity shows that since the earliest days people needed to count and compute, either for measuring the months and the seasons or for commerce and constructions. The means used for performing calculations were whatever was available, and thus gradually progressed from manual to mechanical, and from there on to electrical devices. Indeed, man started off by counting on his digits, a fact attested by the use of the word digit to mean both “any of the ten numbers from 0 to 9” and “a finger, thumb or toe” (Oxford Advanced Learner’s Dictionary). The need for counting and tracking occurrences in the physical world is witnessed by primitive calendars like the one at Stonehenge, 2,800 B.C., or by primitive calculators like the abacus. The abacus, the most common of which comes from China, was man’s first attempt at automating the counting process, and it involved the idea of positional representation: the value assigned to each bead (pebble, shell) was determined not by its shape but by its position. The transition to a qualitatively superior way of doing computation had to wait until the 17th century when Pascal built the first mechanical adding machine (1642), based on a gear system. In his machine, based on the design of Hero of Alexandria (2 A.D.), a wheel engaged its single tooth with a ten-teeth