&gt; For most cultures on Earth, the last color they named was blue --- this is thought to be due to its rarity in nature.<p>And for the sky and water that we&#x27;d now call blue, there was no need to differentiate between blue and green. You might want to tell someone &quot;Don&#x27;t pick the green fruit, only the ones that have turned red,&quot; so having a single word for green and red would be a problem. But the sky is always going to be either blue, gray, or red, so a single greenblue word doesn&#x27;t constrain your communication about it.<p>I can think of a couple exceptions, like blueberries (where you can refer to their darkness instead of hue for ripeness) and green tinted skies in severe storms, but it definitely makes sense that the word for blue would be invented last.