Symbiogenesis leads to parallel processing of genetic code, both within an individual multicellular organism and across the species as a whole. Given that nature allows a plenitude of processors but a limited amount of time, parallel processing allows a more efficient search for those sequences that move the individual, and the species, ahead.

Efficient search is what intelligence is all about. "Even though biologic evolution is based on random mutations, crossing and selection, it is not a blind trial-and-error process," explained Barricelli in a later retrospective of his numerical evolution work. "The hereditary material of all individuals composing a species is organized by a rigorous pattern of hereditary rules into a collective intelligence mechanism whose function is to assure maximum speed and efficiency in the solution of all sorts of new problems... and the ability to solve problems is the primary element of intelligence which is used in all intelligence tests.... Judging by the achievements in the biological world, that is quite intelligent indeed."[21]

A century after On the Origin of Species pitted Charles Darwin and Thomas Huxley against Bishop Wilberforce, there was still no room for compromise between the trial and error of Darwin's natural selection and the supernatural intelligence of a theological argument from design. Samuel Butler's discredited claims of species-level intelligence--neither the chance success of a blind watchmaker nor the predetermined plan of an all-knowing God--were reintroduced by Barricelli, who claimed to detect faint traces of this intelligence in the behavior of pure, self-reproducing numbers, just as viruses were first detected by biologists examining fluids from which they had filtered out all previously identified living forms.

"The notion that no intelligence is involved in biological evolution may prove to be as far from reality as any interpretation could be," Barricelli argued later, in 1963. "When we submit a human or any other animal for that matter to an intelligence test, it would be rather unusual to claim that the subject is unintelligent on the grounds that no intelligence is required to do the job any single neuron or synapse in its brain is doing. We are all agreed upon the fact that no intelligence is required in order to die when an individual is unable to survive or in order not to reproduce when an individual is unfit to reproduce. But to hold this as an argument against the existence of an intelligence behind the achievements in biological evolution may prove to be one of the most spectacular examples of the kind of misunderstandings which may arise before two alien forms of intelligence become aware of one another."[22] Likewise, to conclude from the failure of individual machines to act intelligently that machines are not intelligent may represent a spectacular misunderstanding of the nature of intelligence among machines.

The evolution of digital symbioorganisms took less time to happen than to describe. "Even in the very limited memory of a high speed computer a large number of symbioorganisms can arise by chance in a few seconds," Barricelli reported. "It is only a matter of minutes before all the biophenomena described can be observed."[23] The digital universe had to be delicately adjusted so that evolutionary processes were not immobilized by dead ends. Scattered among the foothills of the evolutionary fitness landscape were local maxima from which "it is impossible to change only one gene without getting weaker organisms." In a closed universe inhabited by simple organisms, the only escape to higher ground was by exchanging genes with different organisms or by local shifting of the rules. "Only replacements of at least two genes can lead from a relative maximum of fitness to another organism with greater vitality,"[24] noted Barricelli, who found that the best solution to these problems (besides the invention of sex) was to build a degree of diversity into the universe itself.

"The Princeton experiments were continued for more than 5,000 generations using universes of 512 numbers," Barricelli reported. "Moreover, the actual size of the universe was usually increased far beyond 512 numbers by running several parallel experiments with regular interchanging of several (50 to 100) consecutive numbers between two universes.... Within a few hundred generations a single primitive variety of symbioorganism invaded the whole universe. After that stage was reached no collisions leading to new mutations occurred and no evolution was possible. The universe had reached a stage of 'organized homogeneity' which would remain unchanged for any number of following generations.... In many instances a new mutation rule would lead to a complete disorganization of the whole universe, apparently due to the death by starvation of a parasite, which in this case was the last surviving organism.... Homogeneity problems were eventually overcome by using different mutation rules in different sections of each universe. Also slight modifications of the reproduction rule were used in different universes to create different types of environment... by running several parallel experiments and by exchanging segments between two universes every 200 or 500 generations it was possible to break homogeneity whenever it developed in one of the universes."[25]

As Alan Turing had blurred the distinction between intelligence and non-intelligence by means of his universal machine, so Barricelli's numerical symbioorganisms blurred the distinction between living and nonliving things. Barricelli cautioned his audience against "the temptation to attribute to the numerical symbioorganisms a little too many of the properties of living beings," and warned that "the author takes no responsibility for inferences and interpretations which are not rigorous consequences of the facts presented."[26] He stressed that although numerical symbioorganisms and known terrestrial life forms exhibited parallels in evolutionary behavior, this did not imply that numerical symbioorganisms were alive. "Are they the beginning of, or some sort of, foreign life forms? Are they only models?" he asked. "They are not models, not any more than living organisms are models. They are a particular class of self-reproducing structures already defined." As to whether they are living, "it does not make sense to ask whether symbioorganisms are living as long as no clear-cut definition of 'living' has been given."[27] A clear-cut definition of "living" remains elusive to this day.