Perhaps the most damning of all Star Trek critiques is the impossibility of sapient races originating on different worlds to mate and produce young. Yet the series opens with a vulcan/human hybrid (the inimitable Mr. Spock).
In this episode, however, the character Sargon states that in his race's antiquity, many, many worlds were "seeded" (not his word) by denizens of his anthropomorphic genotype - similar to that of standard earth humans. This allows the possibility of similar DNA arising from many worlds that could be similar enough to fruitfully mate. It doesn't actually matter whether advanced forms of life survived on these planets, but the mere unavoidability of multi-cellular entities, and even strings of nucleotides being incorporated in the DNA of all creatures' genome at least allows for possibilities.
In this episode, however, the character Sargon states that in his race's antiquity, many, many worlds were "seeded" (not his word) by denizens of his anthropomorphic genotype - similar to that of standard earth humans. This allows the possibility of similar DNA arising from many worlds that could be similar enough to fruitfully mate. It doesn't actually matter whether advanced forms of life survived on these planets, but the mere unavoidability of multi-cellular entities, and even strings of nucleotides being incorporated in the DNA of all creatures' genome at least allows for possibilities.