Scientists use the relationship between the dna of various species to estimate how long ago they diverged from each other evolutionarily. evidence shows that some of these evolutionary changes occurred in a clock-like fashion over a long period of time. what must be true for this explanation to be considered a theory? it must be proven by at least three different sets of experiments with all data documented carefully. all of the current evidence must support this as the best explanation scientists can offer. it must represent the beliefs and opinions of the majority of the leading scientists in the field. all of the scientists in the related field must vote for this hypothesis to become a theory.