I do seem to remember being taught in school that the definition of species is &quot;organisms that can reproduce and generate fertile offspring&quot;.<p>Apparently, though, it&#x27;s not that simple: <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Species_problem" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Species_problem</a>