Edward O. Wilson, in The Diversity of Life wrote (emphasis mine):

Ninety-nine percent of the animals find their way by chemical trails. […]

Animals are masters of this chemical channel, where we are idiots. But we are geniuses of the audiovisual channel, equaled in this modality only by a few odd groups (whales, monkeys, birds). So we wait for dawn, while they wait for the fall of darkness; and because sight and sound are the evolutionary prerequisites of intelligence, we alone have come to reflect on such matters […]

I'm getting this from an anthology (Dawkins' "Modern Science Writing") so I don't see how Wilson supports this statement, and my google-fu is bringin up nothing relevant-seeming.

My question is: why are sight and sound prerequisites for a species to evolve intelligence?


3 Answers 3


To answer your question, we must first ask the question What is defined as intelligence?

A googling will tell you that most people believe intelligence to be something related to apes or even more conservatively to humans. But, I find this to be a bit unpragmatic. The closest level of abstraction I find towards defining intelligence is this wiki on Animal Cognition. Having said so, I personally would define intelligence on a much more abstract level.

Intelligence can be broadly defined as a learned response towards an external stimulus, providing the organism with an increased fitness/survival within it's ecosystem.

So Intelligence can be broken down into two parts

  1. Memory of a stimulus
  2. A programmed response towards that stimulus

This is a very famous video showcasing intelligence in the animal world; Crow Intelligence test

But My objective is to state that sight and sound are are not at all prerequisites of intelligence.

This paper from way back in 2014 is I think the best that I can state

Memory and Fitness Optimization of Bacteria under Fluctuating Environments

In this particular paper the authors test the capacity of E coli to produce a response within fluctuating environments, and they find that as the generations progress the later generations take lesser time to produce a response towards the stimulus. They also note that what happens if the prior external environmental state is restored. In such a case later generations become optimised for that particular state.

This is a very good example of memory which is stored at the level of DNA, and a level of intelligence is manifested in a microbial system. So therefore, can you really state that "sight- and sound" are pre-requisites of intelligence. I would say No They are not, that would be an over-simplistic way of what intelligence really is.


He may be referring to the fact that many nocturnal animals wait for the cover of darkness to be able to get their food safely or in order to cloak themselves to approach their prey better. However, this seems to be a matter of personal opinion. He wants you to think that we are smarter because we have to hide and hunt in broad daylight. I haven't been able to support his theory as bats can be considered very intelligent - and they primarily hunt at night.

In fact, we also consider dogs - and their wolf counterparts - to be intelligent as well, and you typically only see wolves at night.

Also, studies are showing that humans who are "Night Owls" are smarter than people who are "Morning Larks" according to a study in Psychology.

If you're interested in different kinds of behaviours and how intelligent they are you can look at BBC Animal Adaptations, which has a really cool list of what abilities each animal has split into categories. Particularly, they have an "Animal Intelligence" section which goes into detail about particular behaviours humans consider to be signs of intelligence. Personally, I think their list is a little out of date - where it is missing a few animals - but by their standards, many of the nocturnal animals have not made it onto the list.

A reason that hearing could be a prerequisite for intelligence is that communication is considered to be a HUGE part of intelligent behaviour. Tool use could be a reason that sight is considered a prerequisite for being intelligent. Really, the five senses (sight, hearing, touch, taste and smell) allow us to really take in the world and adapt to it properly. Sight, hearing and smell typically allow us to be warned of dangers but the fact is that we have to be intelligent enough to know what to do with the information.

Summary: Intelligence can be measured in many different ways. Edward O. Wilson could have been looking at a number of different things when he came to his conclusion (where sight and sound were required for intelligent beings). The truth is that it is all speculative.

If you judge a fish's intelligence by its ability to climb a tree, it will grow up thinking that it's stupid.

Subsequently if you judge my intelligence by my ability to spell, I will also go on thinking I'm stupid ;)

  • 2
    $\begingroup$ I have not judged you by your ability to spell English words, I have merely corrected them. $\endgroup$
    – MattDMo
    Commented Jul 25, 2015 at 3:21

With all due respect to Dr. Wilson, this is just an anthropocentric, post hoc ergo propter hoc logical fallacy. Dr. Wilson looked around the world we live in, saw that most intelligent creatures navigate by sight and/or sound and concluded that those sense are a prerequisite for intelligence. I see absolutely no evidence to support this theory.

First of all, that is a classic fallacy. It is the equivalent of a 17th century European going to Africa and concluding that having pinkish skin is a prerequisite for the development of technology. Or if I were to go to Japan and conclude that having an epicanthic fold is a prerequisite for making good sushi.

The fact that the paths chosen by the evolutionary process on this planet are skewed towards sight and sound for more intelligent species does not in any way imply that those senses are needed for intelligence. What is needed are ways of detecting and reacting to the environment as quickly as possible. Light and sound are indeed particularly well suited for this since they travel several orders of magnitude faster than chemical diffusion. That's a good reason to conclude they might have given a selective advantage to the species relying on those two waves to detect their predators or prey.

There are, however, other options. Radar (bats) and sonar (dolphins) can be thought of as sight (or hearing) but are quite different. They both involve the emission of a wave and analysis of what is reflected back. Sight involves the analysis of light emitted by the sun and reflected by the environment. Being able to use your own body to emit the energy needed for your perception would seem to be a huge advantage. Our wonderful sight only works half of the time.

You could also, conceivably, have very fast perception based on things like:

Some of the above already exist in species on this planet, others do not. Admittedly, using quantum entanglement would be kind of tricky. On the other hand, I see no reason why tiny disturbances in the gravitic field could not be detected just as tiny disturbances in the electromagnetic fields are by animals like sharks and cockroaches.

The main point of all this is that the fact that intelligent animals on this planet tend to do X does not in any way imply that X is a prerequisite for intelligence. Quite frankly, I expected better of someone like Dr. Wilson than such baseless speculation presented as fact.


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