Why are octopuses considered so intelligent

Overview

Octopuses are widely regarded as the most intelligent invertebrates on Earth, captivating scientists and the public alike with cognitive abilities that seem to defy their evolutionary origins. Our last common ancestor with the octopus existed more than 500 million years ago, yet these soft-bodied, boneless mollusks have evolved a form of intelligence that bears striking resemblance to that of vertebrates. Most invertebrates, such as insects, jellyfish, or worms, rely on simple reflexes and instinctive behaviors to survive. Octopuses, however, show learning, problem-solving, and even playful behavior that go far beyond basic reflexes.

The Octopus Brain and Nervous System

Octopuses possess approximately 500 million neurons distributed between their brains and arms. This neural architecture is unique in the animal kingdom. Their brains are built in a completely different way from those of dolphins or primates, which makes their intelligence especially intriguing from a marine biology perspective. Scientists credit their cognitive abilities to a combination of a large brain, advanced sensory systems, and a relatively long lifespan for an invertebrate, which allows time for learning and memory formation.

Behavioral Flexibility and Problem-Solving

From a behavioural point of view, the flexibility with which an animal can adapt itself and adjust its behaviour to novel situations is a good indicator of its cognitive abilities. Numerous studies indicate that octopuses possess great flexibility in their behaviours, whether expressed in their natural environment or inside a laboratory tank. Lab studies show that octopuses can solve puzzles, learn to open jars, and navigate mazes — skills typically associated with vertebrates. In some behavioral tests, their performance rivals that of certain fish, birds, and even young mammals.

A particularly impressive example of their intelligence is their ability to manipulate an L-shaped object so it can pass through a small square opening in a wall. Octopuses also excel in discriminative learning: confronted with two objects, they learn to attack one of them in exchange for a reward, basing their choice on characteristics such as colour, shape, texture, or taste, and they can retain this information for several months.

Ecological Pressures Driving Intelligence

Their life in complex, three-dimensional reef and rocky environments means they must constantly assess threats, hunt moving prey, and navigate intricate spaces. This ecological pressure helps explain why their intelligence is so advanced compared with other invertebrates. Interestingly, intelligent animals are generally supposed to be social animals that live a long time, as managing relationships requires some intelligence and brains take a long time to mature. But the intelligent octopus breaks these rules — it is largely a solitary creature with a short lifespan.

Genetics: "Jumping Genes" and Shared Biology with Humans

Scientists have uncovered a clue that may partly explain the cephalopods' remarkable intelligence: a genetic quirk also seen in humans. These clues are called "jumping genes," or transposons, which make up 45% of the human genome. Jumping genes are short sequences of DNA with the ability to copy and paste or cut and paste themselves to another location in the genome, and they have been linked to the evolution of genomes in multiple species. Genetic sequencing revealed that two species of octopus — Octopus vulgaris and Octopus bimaculoides — also have genomes that are filled with transposons, according to a study published in the journal BMC Biology. These findings not only connect jumping genes to octopus intelligence, they also suggest that LINE transposons have some role in cognitive processing.

A Parallel Evolution of Intelligence

Even though octopuses are not closely related to animals with backbones, they nonetheless demonstrate behavioral and neural plasticity similar to that of vertebrates. In the field of marine biology, octopuses stand out as one of the most intelligent invertebrates, often compared to "smart animals" like dolphins and primates. Their intelligence has sparked a wave of research into how such complex minds evolved in animals with no backbone, raising questions about the nature of intelligence itself. Their story is, in many ways, one of convergent evolution — a remarkable demonstration that high intelligence can emerge through more than one evolutionary pathway.