John Evans, a mathematician friend of mine in Cambridge England, came up with a formula that specifically allows one to estimate the relative complexity of nervous systems in the animal kingdom, from C. elegans to the human brain. It takes into account not just the number of neurons in the brain, but also the number of synaptic connections that link neurons to one another, and in a second version, the encephalization quotient.

In one sense, the formula is simplistic, yet to my knowledge it is the first attempt at such a calculation, so it will be interesting to see if it actually works.

The underlying supposition to be tested is that the calculated neurocomplexity is correlated with something that we will define loosely as animal intelligence, basically the ability to learn from experience and then to use the learned information to solve a problem. What follows is a list of familiar animals, and I challenge readers to put them in order from most intelligent to least intelligent. There is no “right” answer, of course, only intuition based on your experience with the animals in question. I don’t want to sort through hundreds of responses, so I will just take the first ten replies that seem to be serious attempts, and in a future column I will reveal a second list calculated according to the Evans equation.

If you can possibly manage to do so, jot down your list before looking at other readers’ lists, and then post it.

This exercise will serve to introduce a significant question: Is there a minimal level of neurocomplexity that must be present for self-awareness and consciousness to arise?

Here are the animals, listed in alphabetical order as a way to randomize them:




Dolphin (bottlenose)

Elephant (African)