Dinosaurs and Intelligence

Dinosaurs arose some 240 million years ago. They became the dominant terrestrial vertebrates after the Triassic–Jurassic extinction event 201 million years ago. Their ascendancy lasted another 135 million years until the Cretaceous mass extinction 66 million years ago opened the world to the eventual rise of mammals and us. The first mammal-like forms appeared some 225 million years ago. But for the next 160 million years, mammals had to find their niches in the shadow of the dinosaurs, characteristically living a nocturnal lifestyle, emerging from burrows to feed only at night. This may have favored the evolution of better eye-sight, smell, touch and hearing to be able to navigate, find food and survive in the dark. But they still had to hide from the dinosaurs.

The question of why dinosaurs never developed cognitive intelligence, despite the many millions of years they were the top vertebrate clade, forms a rich WWW vein. (Search for the question and check it out.) Some dinosaurs did get quite intelligent in the form of birds. Some avian dinosaurs are even tool users. But there is no evidence that dinosaurs ever achieved anything like the human intelligence which has allowed us to alter our environment in ways both planned and unplanned. We human beings (the last surviving species of the homo genus) have been around for only some 200 thousand years. If one starts counting with the Australopithecus, then our progenitors go back around 3.6 million years. In either case, the fact that dinosaurs didn’t develop intelligence and complex technology even over a hundred million years while we did in just a few raises at least two questions: Is the rise of intelligence inevitable and does it have survival value over the long run?

The second question may be easier to answer. Dinosaurs and all other life on earth have done pretty well without human-style intelligence. Indeed, intelligence has not played a major role over the four billion years of life on earth. Some dinosaurs may have been clever hunters, as are wolves for example, and Jurassic Park has shown us a possible example. But they apparently found the use of claw, teeth, armor and size sufficient to last until a huge asteroid took them out with most other life. This leads to an answer to the first question, was the rise of intelligence inevitable. We can never know what might have happened with the clever dinosaurs if they were given the next 65 million years instead of mammals. Large brains need extra oxygen and are costly in energy. Maybe there would never have been any evolutionary advantage to making the investment. Human intelligence may be a cosmic accident, the result of a particular rock hitting at a particular moment allowing the burrowing underclass – mammals – to take their furtive ways into the sunlight.

So to return to the question of the long-term survival value of our big brains, the dinosaurs did really well without them and it is not clear that they will save us from ourselves.