Aristotle stated in his book History of Animals more than 2,000 years ago that the octopus is a stupid creature because it will approach a man's hand if it is lowered into the water. But in more recent years, octopuses' curious nature has helped scientists learn about their intelligence.
Essays like Sy Montgomery's "Deep Intellect" and movies like the Oscar-winning documentary My Octopus Teacher portray octopuses as inquisitive, sensitive, and even playful animals.
Is an Octopus Intelligent?
Researchers are discovering astonishing parallels to our own minds, along with bizarre differences in how our species experiences the world, as they continue to study the genetics, brains, and sensory abilities of octopuses.
Clams and snails are both members of the phylum of mollusks, which includes octopuses. Evolutionarily speaking, we diverged from one another about 600 million years ago; a flatworm is our most recent common ancestor. Despite this evolutionary gap, there are fundamental similarities between our brains.
Octopuses: How Intelligent Are They?
Octopuses employ that intelligence in a number of different ways. The Internet has a soft spot for tales of octopuses sneaking back home after escaping their tanks, squelching across the room, and munching on other aquarium inhabitants.
Additionally, according to Wen-Sung Chung, a researcher at the University of Queensland who specializes in cephalopod neurobiology, their hunting behaviors in the wild exhibit "highly complex, calculated behaviors."
"They can do foraging navigation based on the landmarks or the polarization patterns of the sky," he claims, and they also engage in "interspecific cooperation hunting: fish and octopus, they can hunt together. There are very few animals like that.
In addition to all of that, says Mather, octopuses engage in play, a behavior usually reserved for highly intelligent creatures like wolves, dolphins, and people.
Human and Octopus Brains
The central processing areas in the brains of both humans and octopuses are responsible for making decisions and gathering and integrating data from various sources, such as our sensory organs.
Our two-lobed, bilaterally symmetrical brains are housed inside of our skulls. Despite all these similarities, however, there are some unexpected differences in our nervous systems. The most striking one may have something to do with the arms, which are an octopus' most distinctive feature.
Tentacles are covered in suckers, but octopus arms literally have a mind of their own. Three-fifths of an octopus's neurons, or nerve cells, are in its arms; each sucker has a unique group of neurons that regulate it. As a result, each arm has a great deal of autonomy when it comes to moving, detecting its environment, and even making simple decisions.
"If I chopped off your arm, it would lie on the floor," asserts Jennifer Mather, a psychology professor at the University of Lethbridge and a scientific consultant for My Octopus Teacher. "If I cut off an octopus's arm, for a while it behaves like a sort of independent entity."
Overall, the octopus brain is "less of a control system than our brain," according to Mather, due to its dispersed network of neurons and autonomous parts. However, Mather also points out that humans have neurons in other parts of our bodies, such as our guts and the long nerve cells that run along our limbs to our extremities. Simply put, octopuses take that idea too far. But according to Mather, it is untrue that octopuses have a brain in each of their arms.
Sensing the World Through Octopus Eyes
Octopus eyes have lenses similar to ours for sensory processing, but they are color blind. Scientists are further perplexed by the fact that octopuses have psychedelic color-changing abilities that they employ for communication and concealment. Instead, polarization—the various directions in which light waves vibrate—can be detected by octopuses.
Given that polarization is less affected by deep water, which tends to filter out colored light, particularly at the reddish end of the spectrum, this may be a more useful sensory tool for octopuses. Octopuses have a variety of ways to process visual information, but they also have impressive chemical sensitivity.
Octopuses also display a ton of behaviors that, when combined with their organization and sensory processing abilities, make them appear extremely intelligent to researchers (as well as non-scientists). According to neuroscientist Anil Seth of the University of Sussex, octopuses can help us understand an intelligence that is very dissimilar from our own.
He claims that considering the inner world of a common octopus can help us comprehend the type of consciousness that, if any sentient aliens exist, they may possess.
Inside an Octopus's Brain
One recent study found that octopus brains contain an unusually high amount of non-coding microRNA molecules used in regulating genes and constructing proteins. Scientists are still learning new mechanisms that explain how octopuses are capable of such cognitive sophistication.
But Mather has a theory regarding the evolutionary pressures that led to intelligent octopuses. She recalls watching Jacques Cousteau's underwater documentaries as a child to see sea life, such as octopuses.
He referred to them as "the soft intelligence," and that actually touches on a crucial aspect of the octopus, she claims. "They lack all of these physical defenses, such as an exoskeleton, spines, and unpleasant tastes. In essence, their means of survival are their cunning.