Peter Godfrey-Smith’s Other Minds makes for an interesting read on the subject of the evolution of intelligence. The book focuses on the octopus and the evolution of intelligent life.Octopuses belong to the same class of animals as squid and cuttlefish (the cephalopods), a class which separated from the evolutionary line that led to humans more than 600 million years ago. As Godfrey-Smith describes, many experiments have shown that octopuses are highly intelligent, and capable of complex behaviours that are deemed to require sophisticated forms of intelligence. They are, therefore, the closest thing to alien intelligence that we can get our hands on, since the evolution of their bodies and brains was, in the last 600 million years, independent from our own evolution.
The book explores very well this issue and dives deep into the matters of cephalopod intelligence. The nervous systems of octopuses brains are very different from ours and, in fact, they are not even organised in the same way. Each of the eight arms of an octopus is controlled by a separate “small brain”. These small brains report to, and are coordinated by, the central brain but retain some ability to act independently, an arrangement that is, to say the least, foreign to us.
Godfrey-Smith leads us through the branches of the evolutionary tree, and argues that advanced intelligence has evolved not once, but a number of times, perhaps four times as shown in the picture, in mammals, birds and two branches of cephalopods.
If his arguments are right, this work and this book provide an important insight on the nature of the bottlenecks that may block the evolution of higher intelligence, on Earth and in other planets. If, indeed, life on Earth has evolved higher intelligence multiple times, independently, this fact provides strong evidence that the evolution of brains, from simple nervous systems to complex ones, able to support higher intelligence, is not a significant bottleneck. That reduces the possible number of explanations for the fact that we have never observed technological civilisations on the Galaxy, also known as the Great Filter. Whatever the reasons, it is probably not because intelligence evolves only rarely in living organisms.
The scientific components of the book are admirably intertwined with the descriptions of the author’s appreciation of cephalopods, in particular, and marine life, in general. All in all, a very interesting read for those interested in the evolution of intelligence.
Picture (not to scale) from the book, adapted to show the possible places where higher intelligence evolved.