Crustacean Cognition

As far as mental acuity goes, crustaceans have been considered to be near the bottom, when evaluating the brains of various families of animals. Crustaceans are arthropods, which include other simple critters like insects and spiders. In particular, crustaceans are hard-shelled animals (the root of the word crustacean is “having a crust”), such as lobsters, crabs, crayfish, and shrimp. Until a couple of years ago, many scholars thought that the brains of crustaceans are so primitive that they can't even feel pain. This allowed seafood lovers to plunk a live lobster in a pot of boiling water, conscience free, believing it to be so stupid that it did not suffer. Now we know better.

A recent scientific finding coming out of the University of Bordeaux shows us that crustaceans are not only able to feel pain, but possess an even greater cognitive ability: they also feel stress. In fact, the study showed that their tiny brains are influenced by some of the same chemicals that our massive human brains respond to. Ahh, I love it... one more belief about the uniqueness of the human species gets shattered. We keep finding evidence that narrows the gap between us and all the other animals. And here's yet another one.

The research conducted by the French scientists conclusively showed that crayfish can experience rudimentary emotions. How? When they gave crayfish a mild electric shock, the creatures hid in dark corners of their aquarium—unlike their unshocked brethren, who did not hesitate to boldly venture into the light. And the shocked crayfish behaved as if they were stressed or shy.

Wondering what might be going on chemically within the tiny crayfish brain, the researchers guessed that it could be due to elevated levels of serotonin—which also affects the moods of humans, when a serotonin imbalance occurs in our brains. When they injected the stressed crayfish with a drug used to treat anxiety in humans, the critters calmed down and began venturing into the light. Crayfish on Prozac!

I don't think that these results imply that we need to begin training crustacean shrinks to counsel depressed lobsters and crayfish. But they do tell us that yet one more mental barrier between us and simple animals has been dismantled. It makes sense that all animals—including humans—have many mental similarities, given that we all have evolved from the same primitive ancestor that came into being some 3.5 billion years ago. We're all together!

Where’s the Dividing Line?

We humans have long believed ourselves to be fundamentally different from other creatures. We’ve pointed with pride to the many achievements of Homo sapiens as proof of our difference, even as evidence of our superiority—achievements such as the Pyramids, Gutenberg’s printing press, and the Twinkie. Of course, we’re far more reluctant to recognize our other unique “accomplishments” such as DDT, instruments of war, and global warming—but that’s a topic for another time.

I find it fascinating that many of the barriers we’ve erected between ourselves and other members of the animal kingdom are tumbling down, as science plods its inexorable way forward. We once were confident that making and using tools distinguished us from all other critters. We pointed to our African ancestors of hundreds of thousands of years ago, who fashioned sophisticated stone tools and then used them to become brilliantly effective hunters. It separated them from the other great apes. Surely that was special!

In the last few decades, however, research has demonstrated that other critters have developed pretty impressive tool skills. We first had to admit that chimpanzees do it, then other primates. More recent studies have shown that even “lowly” crows construct and employ some complex tools.

Well, OK, if we’re not unique in tool use, surely we are fundamentally different in our cognitive abilities. You know, that big brain of ours, with its massive cortex. In particular, we’d like to think that our consciousness, our self-recognition is unique. A dumb animal looks at its reflection in a pond and just sees another dumb animal, right? It has no ability to comprehend that it’s staring at itself, right?

Wrong. Numerous clever experiments have placed animals in front of mirrors (they do it with mirrors!) and have clearly demonstrated the existence of self-recognition. (On the part of the animal, that is. I assume the researchers already were able to recognize themselves.) In a recent study a dot was attached to a magpie, in such a way that the dot could be seen by the magpie only in a mirror. Guess what? The bird soon realized that the mirror image was itself (it began scratching at the dot) and not another animal.

Will these results begin to sink into our psyches and tell us that we are not as different and as unique as we once erroneously believed? Will we soon come to revere all creatures (not just humans), rather than insensitively abuse them? We’re all in the same boat—Homo sapiens, all the way “down” to bacteria. That boat is called Earth and it needs the mutual acceptance and tolerance of all its critters—especially from us, the critter who believes it’s on top.