Credit: Flickr user endogamia
Imagine being trapped in a small pressurized underwater chamber (like a diving bell) where you were fed once a day by an octopus that tossed food in from the opening in the floor. Each day an octopus also reached in to poke you gently with a stick. Suppose this went on for two weeks. Do you think you’d be able to figure out that there were actually two octopuses—one “poker” and one “feeder”? Would you be able to tell the difference between the two?
Octopuses are so different from humans that it might actually be rather difficult for you to tell them apart—especially since you would only be able to see them through the distorting lens of the water. On the other hand, if you did manage to figure out which octopus was which, you might be able to get out of the way of the stick when the “poker” showed up. You also might be able to demonstrate to the octopuses that you were “intelligent,” perhaps inspiring them to treat you better while in captivity.
Obviously this is just a thought experiment, and the real research was done in reverse, but hopefully this example gives you some sense of how difficult the problem of octopus intelligence really is. Because octopus brains evolved independently from human brains, their anatomical structure is very different from our own, so understanding whether octopuses are “intelligent” is not a simple task. How would you tell if an eight-legged alien from another planet was intelligent?
Earlier this month, Mike Lisieski, a student at the University of Buffalo who blogs about octopuses and other cephalopods, discussed an attempt to assess octopus intelligence that was published in this month’s edition of the Journal of Applied Animal Welfare Science. Eight wild octopuses were fed or gently poked by one of two identically-clad researchers at the Seattle Aquarium, and after two weeks, the octopuses responded differently to the “feeder” and the “poker” when they approached the tank without food or sticks. This suggests that octopuses can recognize different humans. Although Lisieski points out that the task isn’t very authentic and could have been made more difficult by clothing the humans differently each day, nonetheless it’s quite impressive that octopuses can do it at all. Wouldn’t it be easier to shrink away from any approaching human, on the chance that it might turn out to be a harasser?
And octopuses have other impressive abilities that appear to signal intelligence. Texas biologist Zen Faulkes discussed a report published last year in Cell, in which researchers observed octopuses carrying coconut shells around, then later using them as hiding places. This seems to be an example not only of tool use, but anticipatory tool use, which has long been believed to be a mark of intelligence. Faulkes has worked with Jennifer Mather, who is known for research on cephalopod consciousness (PDF link). Mather has observed octopuses modifying their dens in a similar fashion, so there’s converging evidence that octopuses are relatively smart. That said, even ants and bees make complex homes for themselves, so that behavior alone may not be enough to qualify as “intelligence.”
Large octopuses have relatively large brains, with hundreds of millions of neurons. That doesn’t put them in league with humans, with perhaps 100 billion, but octopuses also have a tremendous number of neurons in their tentacles—more than in their brains, says biology researcher Hannah Waters. If an octopus’s nervous system is so radically different from ours, then isn’t it possible that octopus “intelligence” is different from human intelligence as well?
Waters points out that octopuses have been observed doing a number of “intelligent” things, like opening screw-top jars, crawling from one tank to another to get a snack, or being trained to solve puzzles. Psychology graduate student Jason Goldman adds that octopuses have sophisticated visual navigation strategies. Does that make them “intelligent?” After all, ants have great navigation skills, too.
Like other cephalopods, octopuses respond to polarized light—and they produce polarized light patterns by changing their skin pigmentation, says Lisieski. Does this mean they might actually communicate with each other using skin-pigment changes? We don’t know. But even if they do communicate with skin pigment, that doesn’t demonstrate that they are any smarter than birds communicating with songs, or dogs communicating with growls and barks.
In short, at this point the evidence of octopus intelligence doesn’t show that we should treat them differently from many other creatures that many humans routinely kill and serve for dinner. Yet the fact that octopuses are so different from us also opens a world of questions: What does “intelligence” mean to a cephalopod? Nearly everyone agrees that we shouldn’t kill or eat apes; are there other creatures that are equally deserving of our mercy? Is intelligence the key element in how we should treat other animals, or do other rules apply? Maybe any creature with consciousness—and by some definitions, this includes not only cephalopods, but every mammal that has been tested—should be given some rights. Lisieski is sympathetic to many arguments in favor of animal rights, but he’s not sure the search for “intelligence” will ultimately offer any insight. If we accorded rights for every clever act, and removed them for every stupid one, many humans might not qualify for rights most of us believe are fundamental.
Dave Munger is editor of ResearchBlogging.org, where you can find thousands of blog posts on this and myriad other topics. Each week, he writes about recent posts on peer-reviewed research from across the blogosphere. See previous Research Blogging columns »
Originally published July 21, 2010