Peter Godfrey-Smith, a professor at the University of Sydney and City University of New York, believes the octopus is the closest thing to an alien living on Earth with us. Octopuses "are the most complex animal with the most distant common ancestor to humans."Octopus Intelligence
In many ways, octopuses seem as different from us as an advanced creature can be and evolve on the same planet. They have three hearts and blue, copper-based blood. They have the ability to change color, which they use for camouflage. Suppose we encountered an extraterrestrial species of intelligent cephalopods who communicated by waves of colors? We would have to learn a whole new mode of language. Octopuses "developed eyes, limbs, and brains via a completely separate route" from us. With neurons distributed through their bodies instead of solely localized in their heads, we might say they have brains in their arms. They show considerable intelligence, such as in escaping from confinement, and they can tell human individuals apart. Octopuses seem to play, another sign of high intelligence. They also display curiosity, which Godfrey-Smith thinks may be evidence of subjective consciousness. If so, consciousness has appeared separately at least twice on Earth.
It has been suggested that a possible reason why they haven't evolved even higher intelligence springs from their reproductive cycle. Male octopuses typically die soon after mating, and females don't live long past the hatching of their offspring. Therefore, adults don't survive to pass on knowledge and skills to their young. Octopuses can't have much of a culture, if any. Their solitary lifestyle (aside from mating) is probably another factor, since gregarious species tend to be more intelligent than solitary ones; interactions with other members of one's species in a group require mental flexibility.
Godfrey-Smith makes the optimistic assumption that the evolution of consciousness at least twice on Earth implies consciousness isn't a rare fluke, but a potentially common natural development. That assumption, if valid, bodes well for the discovery of sapient beings elsewhere in the universe. If a race of giant octopuses on another planet—perhaps one mainly or entirely covered by water—overcame the disadvantages of their short, solitary lives, maybe by evolving a long-lived, asexual caste responsible for the care and education of the young, they could create something we would recognize as a culture.
Margaret L. CarterCarter's Crypt