Warming up to the idea of smart tortoises

One popular way to describe our brains is to think of them as composed of three parts, arranged from most primitive to most advanced.

At the top is the human brain, where we think. This lies both figuratively and literally on top of the mammal brain, where we perceive and respond physically to our surroundings. At the bottom is the reptile brain. Here we experience our basest feelings and instincts.

But one reptile, the red-footed tortoise, is working to upset that comfortable hierarchy.

In an article titled “Cold-blooded Cognition: Tortoises Quick on the Uptake,” published online by New Scientist on December 26th, Jeff Hecht reports on the results of new research into tortoise thinking, research that challenges the widespread idea that reptiles are as thick of mind as tortoises are of shell.

The article relates how one researcher, Anna Wilkinson, decided to see if her pet red-footed tortoise, Moses, could solve the kinds of maze problems typically posed to laboratory rats.

Most research with reptiles showed them to be pretty dim, as these slow-witted animals failed to master even rudimentary problems. But Wilkinson’s tortoise not only solved the standard 8-arm maze test; Moses also devised an efficient strategy for finding the optimal number of food treats even when the usual cues were removed.

Wilkinson read all the research and realized that one crucial difference between her study and earlier research was that Moses was tested in a warm environment, almost as warm as the tropical climate native to red-foots.

Could it be that some of the other reptile tests failed because their cold-blooded subjects were, well, cold? Maybe it was the light that was dim, and the animals’ wits were cold because the poor dears were in thermal conservation shutdown?

Expanding the research, Wilkinson and her supervisor, Ludwig Huber, found that tortoises passed several gaze-following tests, suggesting something like a “theory of mind,” something never before demonstrated in reptiles.

Not only could the subject red-foots follow another animal’s gaze, a clearly useful skill for an animal that needs to find food and avoid predators, but they could also “learn” how to find unseen food. When one tortoise disappeared from sight behind a screen, then emerged from the other end with a food treat, observing tortoises copied the behaviour, apparently “reasoning” that there was a food source behind the screen, where they couldn’t see it.

This kind of behaviour suggests not only “theory of mind” but some ability to plan, to predict the unseen future outcome of an action. Pretty impressive stuff for the “reptile brain” we all know from Psychology for English Majors 102.

Wilkinson and Huber suggest that further study of reptilian cognition could yield useful insights into how and when different kinds of thought spread through the animal kingdom. If reptiles and mammals split some 250 million years ago, does that mean that all of the shared mental skills were present at least in rudimentary form all those years ago? Or did similar cognitive abilities evolve separately in different animal groups, from a similar starting point?

There are limits to any comparison with the higher mammals, however. Further tests attempted to demonstrate tortoisian empathy, but failed. Apparently, tortoises can think, but they don’t have a lot of compassion. Perhaps, for an animal so far removed from the mammal line, empathy is too much to ask.

But if you want to find food treats in a lab maze, I’ll bet that Moses would be happy to guide you.