&gt;Since they do not have any evolutionary advantage, they cannot spread in the population<p>This is not true, the question isn&#x27;t whether neutral changes <i>can</i> spread, but simply what percentage of molecular changes that spread are neutral. In fact I think that molecular evidence has shown pretty convincingly that on the genome scale <i>most</i> changes are neutral, vindicating the Neutral theory of evolution:<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Neutral_theory_of_molecular_evolution" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Neutral_theory_of_molecular_ev...</a>