Problem-Solving Minds Inside an Octopus

Octopuses occupy an unusual position in the animal kingdom: invertebrates, a group not typically associated with sophisticated cognition, that nonetheless display problem-solving abilities, memory and apparent curiosity that rival those of many vertebrates generally considered far more intelligent. This has made them a subject of intense fascination for researchers studying the evolution of intelligence. Laboratory studies have repeatedly demonstrated that octopuses can learn to navigate mazes, open securely fastened jars to retrieve food hidden inside, and in some documented cases, use readily available objects such as coconut shells as portable shelters, carrying them across open ground to be assembled later, a behaviour some researchers have controversially described as a rudimentary form of tool use. Individual octopuses also appear capable of recognising specific human caretakers, at times behaving quite differently toward people they associate with positive or negative past experiences. What makes octopus cognition particularly striking to researchers is how differently it is organised compared to vertebrate brains. Roughly two-thirds of an octopus's neurons are located not in its central brain but distributed throughout its eight arms, each of which is capable of a considerable degree of independent sensing and movement, seemingly without requiring constant, moment-to-moment direction from the central brain. This has led some researchers to describe octopus cognition as unusually distributed, raising intriguing and still largely unresolved questions about how, or indeed whether, a coherent overall sense of the body and its surroundings is unified across such a decentralised nervous system. Because octopuses diverged from the evolutionary lineage leading to vertebrates several hundred million years ago, their sophisticated cognitive abilities are widely regarded as having evolved entirely independently, rather than having descended from any shared ancestral form of complex intelligence. This makes them, in the view of many researchers, one of the most valuable available case studies for understanding how intelligence itself can evolve along fundamentally different paths.