most functional proteins are made of hundreds of amino acids. Even a relatively short protein of, say, 150 amino acids represents one sequence among an astronomically large number of other possible sequence combinations—approximately 10195. That is an enormous number, the digit 1 followed by 195 zeroes. Intuitively, this suggests that the odds of finding even a single functional sequence—a working gene or protein—as the result of random genetic mutations may be prohibitively small, even taking into account the time available to the evolutionary process.
