The Dragons of Eden

Maybe this book was exciting when it came out, but I wouldn't recommend it at this time. Science and technology have moved on and many of the ideas he references are dated. Much of his exposition rests on the now discredited Triune Brain theory. But some parts don't even need new science to contradict them, they contradict themselves! For example, he speculates that sleep is an adaptation of mammals to avoid nocturnal predators... Which are themselves mammals and also sleep, they just sleep during the day. How does that make sense? He even admits that modern mammals which are also nocturnal predators (ie cats) do sleep a lot, but regards it as a vestigial trait and not contradictory to his theory. What?
The tie ins with mythology are neat but not explored in much depth. In fact that is a general theme of this work; refer to some neat thing for a paragraph then drop it. Discuss a real study for a paragraph then idle speculation for three or four more. The napkin calculations are also hilarious. He tries to design a study to measure the bandwidth of the human visual processing system in a pretty bananas way, measures it (n=1) then declares victory and starts comparing it to things.

Lots of people misses the point with calling this book outdated, and even random. What the author has to say about the human brain itself can be purely wrong, it doesn't necessarily matter in the sense of human intelligence, because this book is about human intelligence, not the human brain. Also note the title that clearly says "speculations".

I'd even say, that this book is a rather fun and easy read about the concept of intelligence in general. Through several biological and linguistic phenomenons Sagan introduces the readers to an unbiased view of human intelligence, that can and should be compared to for example animal intelligence. Even when he talks about the estimates of some information specifications of a human brain, he is comparing human intelligence to machine intelligence.

This book may be light on the side of science but it's a really great introduction to the concept of intelligence in general. What I did enjoy as well is reading how empathic and reasonable he is with every matter covered in this book.

It has interesting or even weird ideas (like cultural myths encoded in our genes) that could be classified science-fiction but the point is getting rid of our biased view on human intelligence, looking at it in a more general way.