The Octopus Is Smart as Heck, But Why?
One theory why primates evolved big brains is because they had hands. Big brains for an animal like a gazelle don’t pay off because, without hands, there isn’t much a gazelle can do with that big brain. Better it use that energy for bigger leg muscles. Primates evolves hands so they could better grasp branches, but, once they had hands, there was a lot more they could do with them, like make tools. A bigger brain for a creature with hands is an evolutionary advantage, because that bigger brain allows complex behaviors that can be carried out with hands. I bet octopuses are intelligent for a similar reason. Its body is like one big hand, and there are lots of complex behaviors it can carry out with those tentacles. Similar for its color changing skin. There are many complex and useful ways that skin can be used, so it pays to have a big brain. The important point is that the bodily appendages came first, and those appendages made it actually useful to have a big brain. I find it more surprising that dolphins became intelligent, but the article is right that living in groups capable of communication and cooperation can similarly make big brains pay off, because the animal can engage in complex group behaviors.