Vallejo nocturno 2014 - Conexions
Where Aplysia has only 20,000 neurons distributed in ganglia throughout its body, an insect may have up to a million nerve cells, all concentrated in one brain, and despite its tiny size may be capable of extraordinary cognitive feats. Thus bees are expert in recognizing different colors, smells, and geometric shapes presented in a laboratory setting, as well as systematic transformations of these. And of course, they show superb expertise in the wild or in our gardens, where they recognize not only the patterns and smells and colors of flowers, but can remember their locations and communicate these to their fellow bees.
It has even been shown, in a highly social species of paper wasp, that individuals can learn and recognize the faces of other wasps. Such face learning has hitherto been described only in mammals; it is fascinating that a cognitive power so specific can be present in insects as well.
We often think of insects as tiny automata—robots with everything built-in and programmed. But it is increasingly evident that insects can remember, learn, think, and communicate in quite rich and unexpected ways. Much of this, doubtless, is built-in—but much, too, seems to depend on individual experience.
Whatever the case with insects, there is an altogether different situation with those geniuses among invertebrates, the cephalopods, consisting of octopuses, cuttlefish, and squid. Here, as a start, the nervous system is much larger—an octopus may have half a billion nerve cells distributed between its brain and its “arms” (a mouse, by comparison, has only 75 to 100 million). There is a remarkable degree of organization in the octopus brain, with dozens of functionally distinct lobes in the brain and similarities to the learning and memory systems of mammals.
Cephalopods are not only easily trained to discriminate test shapes and objects, but some reportedly can learn by observation, a power otherwise confined to certain birds and mammals. They have remarkable powers of camouflage, and can signal complex emotions and intentions by changing their skin colors, patterns and textures.
Darwin noted in The Voyage of the Beagle how an octopus in a tidal pool seemed to interact with him, by turns watchful, curious, and even playful. Octopuses can be domesticated to some extent, and their keepers often empathize with them, feeling some sense of mental and emotional proximity. Whether one can use the “C” word—consciousness—in regard to cephalopods can be argued all ways. But if one allows that a dog may have consciousness of an individual and significant sort, one has to allow it for an octopus, too.
Nature has employed at least two very different ways of making a brain—indeed, there are almost as many ways as there are phyla in the animal kingdom. Mind, to varying degrees, has arisen or is embodied in all of these, despite the profound biological gulf that separates them from one other, and us from them.4