Octopuses Challenge Traditional Views on Intelligence Evolution

For decades, evolutionary biology linked large brain size and intelligence primarily to social living, based on the "social brain hypothesis" which suggests animals in complex social groups develop bigger brains to manage relationships. However, a new study published in iScience examining 79 species of cephalopods, including octopuses, squids, and cuttlefish, challenges this view. These animals typically lead solitary lives, often short-lived and sometimes cannibalistic, without social structures that require complex interactions.

Led by anthropologist Kieran Besaoua and behavioral economist Michael Motokerishna, the research compared ecological and behavioral data across these species and found a clear pattern: brain size correlates more strongly with environmental complexity than sociality. Cephalopods inhabiting shallow, complex seabeds tend to have larger brains. Psychologist Dr. Jennifer Mather, a co-author, emphasized that solitary animals can develop large brains if their environment is sufficiently rich and challenging to reward learning.

Octopuses exemplify this, using their soft bodies to adapt to various shapes, hunt diverse prey, use tools, and navigate crevices, all requiring advanced cognitive abilities independent of social interaction. Motokerishna's "cultural brain hypothesis" from 2018, which posits brain evolution is driven by the capacity to acquire and manage information through social or non-social learning, is supported by these findings.

The study concludes that while social living is one evolutionary pressure for larger brains, it is not the only path. Adaptation to complex physical and environmental challenges also drives intelligence development. Motokerishna summarized, "Octopuses, squids, and cuttlefish prove there is more than one way to evolve intelligence," highlighting the need to question scientific paradigms in biology.