Manipulation Complexity and the Intelligence of Sea Otters

Last year a paper was published by Sandra et al that allowed us to connect primate intelligence with manipulation complexity. Of particular interest to me, was that it indicated possibilities to measure the intelligence of non-primates. Unfortunately, connecting this work to cetaceans would be problematic, not because their manipulation abilities are inferior, but because they are so different. In order to understand, please watch the one minute video on bottlenose dolphin manipulations of an air bubble below.

It would require extraordinary mathematical modeling to compare the manipulation capabilities of cetaceans and primates, but what of other dexterous mammals? The non-primate mammal that comes to the fore in this category is the sea otter. It may be renowned for its feeding complexity and dexterity, but how can we use this to place its intelligence?

A full study would take time, yet it may be that we have enough information just from watching them feed on YouTube! Their videoed feeding is almost always of level three, as defined in that paper. If that were an unbiased sample (which it isn’t), and they were a primate, it would place their likely intelligence at 100 on my primate scale, and just under the macaque. We have, however, more clues. Sea otters are tool users. According to those who study them, tool use is not instinctive, but learned, making their use  analogous to that in primates. That alone, would suggest an intelligence > 80 points. Likewise they are users of extractive foraging, which implies an intelligence > -60. Several other tests also vouch to their superior intelligence, though none that I can use for a direct comparison. Even after this brief investigation, we can be confident that the sea otters can be placed as one of the forty or fifty most intelligent genera on Earth. This begs the question of how such a small mammal can be so intelligent.

The next most applicable animal to this approach may be the raccoon. About a hundred years ago, the raccoon was the leading nonhuman subject of cognitive testing in North America, though little research has been done subsequently. At that time, leaders in the field felt their intelligence superior to cats or dogs, but were they? If we use the same approach we would calculate a YouTube manipulative complexity that corresponds to around 60 points on my primate cognition scale. They are not tool users, which suggests a cognitive ability < 100 on that scale, and they have not been observed using extractive foraging, suggesting a value < 50. This approach can’t pin down their level of intelligence to the narrow band that it does for the sea otter, however we can conclude that, if they are more intelligent than the domestic dog, it can only be by a whisker.

Markers for Intelligence in Dexterous Animals

 primate IQ  Marker
 > 80  tool use
 >-60  use of extractive foraging
< 100  no tool use
 < 50  extractive foraging absent

The sea otter is like no other otter. The rest of them have thick layers of blubber, but it relies on its fir and high metabolic rate to keep warm. Birds need such a high metabolic rate to fly that they can support an abnormally active brain for their size, and now it looks as if sea otters might be similarly placed. Using those findings of Sandra et al. we have found yet another sea creature of unusually high intellect.


Since I wrote this I have noticed that we also have good neocortical neuron data for raccoons. Their 453 million neurons would give them an expected intelligence of zero on my scale. If we add to that model knowledge of their wide omnivorous diet, our expectation would be that they are in the 10-50 range.