I found a brilliant example of evolution recently......
An experiment held in 1993 by an Engineer called Adrian Thompson....
Thompson wondered what would happen if you used the 'genetic algorithm' approach to an electric circuit. Decide on some task, randomly cross-breed circuits that might or might not solve it, keep the ones that do better than the rest, and repeat for as many generations as it takes.
Most electronic Engineers, thinking about such a project, will quickly realise that it's silly to use genuine circuits. Instead, you can simulate the circuits on a computer (since you know exactly how a circuit behaves) and do the whole job a lot more quickly. Thompson mistrusted this line of argument, though: maybe circuits 'knew' something that a simulation would miss.
He decided on a task, to distinguish between two input signals of different frequencies, 1Khz and 10Khz. Think of them as a low tone and a high tone. The circuit should accept the tone as an input signal, process it in some manner to be determined by it's eventual structure, and produce an output signal. For the high tone, the circuit should output 0 Volts, for the Low tone, a steady 5 volts. (Actually, these properties weren't specified at the start, and two different steady signals would have been acceptable.)
It would take forever to build thousands of trial circuits by hand, so he employed a 'field programmable gate array'. This is a chip that contains a number of tiny 'logic cells' - mildly intelligent switches, so to speak, whose connections can be changed by loading new instructions into the chip.
Those instructions are analogous to DNA code and can be cross bred, which is what was done.
He started with an array of 100 logic cells and used a computer to randomly generate 50 instruction codes. The computer loaded each set into the chip and fed in the two tones, and picked those which reacted best to the signals.
Those that did not react with the signals were 'killed off' and the surviving instruction blocks were 'bred' with each other.
What is most surprising about the experment, however, is not the details, it's the solution.....
By the 220th generation, the fittest circuit produced outputs that were pretty much the same as the input. Basically acting like a bare wire.
By the 650th generation, the low-tone output was steady, but the high-tone output still produced varying output. It took to generation 2800 for the circuit to behave exactly as wished.
The strange part about the final circuit is this. No Human engineer could ever have invented it. Indeed, no human engineer would ever have been able to achieve that result with a mere 100 logic cells. You cannot even make a timing-clock with 100 logic cells. But the new circuit didn't
bother with a clock.
Further study of the circuit showed the final solution, in fact, only used 32 cells, 5 of which were in no way whatsoever connected to the circuit, and yet the circuit failed to work if they were not set in that manner.
Thompson described it thus : 'Really, I don't have the faintest idea how it works.'
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Not trying to start a creationist/evolution row here, but I found it incredibly interesting
