Under the sea

This post is based on Other Minds: The Octopus, the Sea, and the Deep Origins of Consciousness, a book by philosopher and diver Peter Godfrey Smith. It’s well worth a read if you’re interested in consciousness (or octopuses) and, I’d argue, even if you’re not. The quotes I use are taken from this book.

First, let’s set the record straight: The plural of octopus is octopuses, but octopodes is also acceptable. Octopi has crept into the vernacular but it is less correct because octopus has its origins in Greek, not latin. (Octopussies is, unfortunately, in no way correct.)

Paul Hewson (sunglasses aficionado and singer-songwriter), Paul the Octopus (soccer analyst and common octopus) — it’s fair to say humans and octopuses have little in common. It’s worth noting though that while octopuses live in the ocean, in a way we’re still as dependent on the ocean. That is to say, the human body being is 60% saltwater. Life began at sea and the only way we migrated to land was by carrying the seas with us. Let’s get a few obvious differences out of the way though.

Everyone knows octopuses have eight arms (or are they legs?) and can squirt ink. This is strange, but stranger still is the fact that they have three hearts, their throat passes through their brain, and they have teal-coloured blood. Copper, not iron, is the oxygen-carrying molecule in octopuses, which gives their blood a blue-green colour. Octopuses are boneless, aside form a beak used for breaking crab shells, so they can deform at will. For example, a 40 stone octopus can fit through a hole the size of a euro coin. An octopus can detach an arm if it is under attack and it will regenerate. With all that said, their mind is more interesting than their body.

Firstly, octopuses are more intelligent than we’ve historically given them credit for. Experiments have shown them to possess long and short term memory, and they have proven their mettle in specific problem solving tasks. The number of neurons in a brain is often used as a measure of an animal’s intellect, and a common octopus brain has 500 million neurons which ranks alongside dogs (whosagoodboy!) and three-year-old children. Curiously, an octopus’s neurons aren’t solely located in the brain. There are as many neurons in the brain as there are outside it, with a lot found in the arms. It’s possible then that information isn’t passed entirely back to the brain, which means that each arm is thinking and acting for itself, with its own memories the brain can’t access. The octopus body “is its own controller, to some extent, rather than a body steered around by the brain.”

At the centre of this ball of shells, there is an octopus. He/she has assembled this shield of shells to protect it from a shark attack. This is from episode 5 of Blue Planet II, called Green Seas.

Not only do octopuses think all over their body, they also taste and see all over their body. Their taste receptors aren’t confined to the mouth, and are found on all of the suckers. As a result, their behaviour is driven by taste as much as it is by touch. Their skin can also sense light, which is a rudimentary form of vision. Again, it is not clear if what the skin sees is sent back to the brain or if the memory is kept locally but both possibilities are bizarre: Either each arm can see for itself and the brain doesn’t know what’s there, or else the octopus can see in all directions at the same time. The skin can rapidly change colour too, which is odd given that octopuses are colourblind. How do they match the colour of their surroundings when they don’t know what colour it is? Cuttlefish belong to the same class of animals as octopuses and can change colour too, as shown here.

Outlining the wacky attributes of the octopus doesn’t really do the animal justice and it downplays one important conclusion made by Godfrey-Smith: Octopuses possess individual personalities. Some are shy, some and confident, and some are fiesty. They can recognise individual humans wearing identical clothing and have favourites. In one laboratory, an octopus would squirt water at a researcher it didn’t like. Another used to squirt water at a nearby lightbulb, causing it to short circuit and turn off because they prefer the dark. Yet another would leave its enclosure at night, crawl across the room to another tank and eat the fish, before returning back to its tank in order to go undetected. Here is is perhaps my favourite anecdote though:

Stefan Linquist, a philosopher who once studied octopus behavior in the lab, puts it like this: “When you work with fish, they have no idea they are in a tank, somewhere unnatural. With octopuses it is totally different. They know that they are inside this special place, and you are outside it. All their behaviors are affected by their awareness of captivity.”

Another tale that illustrates Linquist’s point was told to me by Jean Boal, of Millersville University in Pennsylvania. Boal has a reputation as one of the most rigorous and critical of cephalopod researchers. She is known for her meticulous experimental designs, and her insistence that “cognition” or “thought” in these animals should be hypothesized only when experimental results cannot be explained in any simpler way. But like many researchers, she has a few tales of behaviors that are baffling in what they seem to show about the inner lives of these animals. One of these incidents has stayed in her mind for over a decade. Octopuses love to eat crabs, but in the lab they are often fed on thawed-out frozen shrimp or squid. It takes octopuses a while to get used to these second-rate foods, but eventually they do. One day Boal was walking down a row of tanks, feeding each octopus a piece of thawed squid as she passed. On reaching the end of the row, she walked back the way she’d come. The octopus in the first tank, though, seemed to be waiting for her. It had not eaten its squid, but instead was holding it conspicuously. As Boal stood there, the octopus made its way slowly across the tank toward the outflow pipe, watching her all the way. When it reached the outflow pipe, still watching her, it dumped the scrap of squid down the drain.

We know that life on Earth is resilient, not rare. Microbes can thrive in inhospitable places such as volcanoes. When it comes to thinking about life beyond Earth, this ability of life to find a way indicates we probably aren’t alone in the Universe. However, while possibly sharing the Universe with some volcanic microbes is all well and good, intelligent life — like you, dear reader — was thought to be extremely rare. The octopus suggests otherwise.

Mammals and cephalopods (the class to which octopuses belong) parted ways 600 million years ago when life was uncomplex, and our last common ancestor was a worm-like creature. (Check out this tree of life.) It follows that evolution has produced intelligent creatures twice: in both the human and the octopus. This reframes how we view potential extraterrestrial life, as the octopus represents “an independent experiment in the evolution of large brains and complex behaviour.” Perhaps, once the seed of life is sown, intelligent beings are not such a rare occurrence after all. Given that there are more planets in the Universe than there grains of sand on Earth, it’s hard to believe that, somewhere, evolution hasn’t produced intelligence elsewhere. For now though, the octopus “is probably the closest we will come to meeting an intelligent alien.”

A similar case can be made about the eye. One of the standard creationist lines of argument against evolution is that only divine intervention, and not a process as simple as evolution, could produce something as intricate as the eyeball. However, both humans and octopuses have remarkably similar eyes. Since our last common ancestor did not have eyes like ours, it follows that we both evolved this eye independently. This suggests complexity isn’t such a challenge for evolution.

Simply put, octopuses have their own ideas, and while we may dominate the planet’s resources, we’re sharing it with other minds which are not unlike our own. “If we can make contact with cephalopods as sentient beings, it is not because of a shared history, not because of kinship, but because evolution built minds twice over.”