qurlyjoe<p>Apparently, some 530 million years ago (give or take) in the <a href="https://mstdn.social/tags/Cambrian" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Cambrian</span></a> age, after about 2.5 billion years of rather plodding <a href="https://mstdn.social/tags/evolution" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>evolution</span></a>, bi-lateral symmetry appeared in animals (after some dabbling in tri-lateral and penta-lateral symmetry) and when brains showed up they were bi-lateral. <a href="https://mstdn.social/tags/Vertebrate" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Vertebrate</span></a>, but still <a href="https://mstdn.social/tags/jawless" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>jawless</span></a>, fishes were swimming after each other for lunch. <a href="https://mstdn.social/tags/Eyes" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Eyes</span></a>, which had already existed for a long while, started showing up in pairs, at the head end of the fishes. (1/3)</p>