You are hereBackground/ Brains and cognition - part 1

Background/ Brains and cognition - part 1


Dolphins are intelligent creatures – everybody knows that much.  But what makes us think dolphins are so smart that some day we might even be able to hold an intelligible conversation with them?  We realize this may sound as a far-out proposition, but we believe there is actually quite a lot of scientific data available that is at least suggestive of the possibility.  So the least we can do (and should, in our opinion) is to be completely open-minded about it, and to investigate this possibility very seriously.  After all, if you are not willing to think outside of the box, you will never be able to map uncharted terrritory.

Dolphin brains

Dolphin & human brains So, what is the scientific evidence on dolphin intelligence that is currently available?  First of all, dolphins (as well as all other cetaceans, i.e. the group that contains all 86 species of dolphins and whales) have large brains.  As can be seen in the picture on the right, in absolute size and weight the bottlenose dolphin brain exceeds ours– and the brain of an orca, which is the largest dolphin, is even four times as large as that of a human.

However, this doesn’t take into consideration that dolphins also have larger bodies to deal with than humans.  To account for this, the Encephalization Quotient, or EQ, was conjured up, which is a measure of brain-to-body-mass ratio.  Humans come out to have an EQ of around 7 to 8, i.e. our brains are 7 times larger than what would be expected given our body weight.  In this interspecies comparison, dolphins rank only second with an EQ of 4 to 5, while chimpansees have an EQ of little over 2.

Sauroposeidon to scaleHowever, critics of the EQ concept have argued that some dinosaurs are known to have had very small brains of only a few centimeters in diameter, thus questioning the assumption that big bodies necessarily need big brains.  Another way of looking at brains as a measure of intelligence is by comparing the surface area of the neocortex to the total brain size.  This is expressed as the so-called gyrification index, and from this perspective dolphin brains do surpass human brains – which can already be seen in the picture above as the large amount of brain folds in dolphins as compared to humans.

A third indication of dolphin intelligence in their brain anatomy is the presence of so-called spindle cells, or Von Economo Neurons (VENs) which are up to three times larger than regular neurons.  Originally thought to be unique to humans and great apes (but since then also found in dolphin, whale and elephant brains), these cells are suspected to be linked to emotional and social intelligence, self-awareness (as demonstrated by mirror experiments), and especially used to gauge the emotions of conspecifics – and therefore suggestive of a “theory of mind”, i.e. the ability of an individual to empathize with what another individual experiences.  This is usually thought of as a sign of high intelligence.

NEXT: Behavioral and experimental evidence for dolphin intelligence