Intelligence in Nature - Jeremy Narby [29]
Octopuses have the largest brains among invertebrates, and scientists have noted their intelligence. Octopuses can run mazes, escape from locked tanks, break into other tanks and steal lobsters, open jars to get at crabs, disguise themselves, and even get angry and turn red. They have half a billion neuronsâ worth of brain power, which is about two hundred times less than ourselves, but a great deal more than snails. Octopuses are adept at finding food in concealed placesâa skill usually associated with big-brained vertebrates such as bears, pigs, and humans. Octopuses camouflage themselves by gauging their environment and, in a fraction of a second, transforming their body shape and the color, pattern, and texture of their skin. Octopuses are wily transformers.
Vertebrates include fish, amphibians, reptiles, birds, and mammals. We vertebrates have internal skeletons that allow us to achieve larger size than most other creatures. And we have backbones and skulls that partly enclose our central nervous systems, providing secure housing for eyes, ears, olfactory senses, and brains. This makes it easier to respond to the environment. But lacking a backbone does not make invertebrates stupid. Octopuses may be spineless, but they can run mazes as successfully as rats.
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INTRIGUED BY THE CAPACITIES of invertebrates, I went to a zoology department at a Swiss university near where I live and asked if somebody could show me a nematode worm. I wanted to look at a living Caenorhabditis elegans through a microscope. The people at the zoology department were not used to dealing with such requests. After all, what business did an anthropologist have wanting to see a nematode? I explained I was writing a book about intelligence in nature and wished to see with my own eyes an invertebrate with a simple nervous system. My request was granted, and I was asked to wait.
On one of the walls in the corridor of the Zoology Department, there was a diagram of the complete body plan of a nematode. Each one of its 959 cells was mapped out in detail. A nematode is barely visible to the naked eye, but it is a complete animal, with skin, brain, mouth, digestive tract, reproductive tract including eggs and sperm, and anus. Nematodes are among the animals that scientists have most studied. They are easy to keep in vast quantities and they reproduce very quickly. And they have transparent skin, which makes it possible to look into their living bodies with a microscope and see their organs function. They also have transparent eggshells, so it is possible to watch their embryos develop.
Nematodes have brains that respond to taste, smell, temperature, and touch. And their neurons send one another an array of chemical signals including serotonin, which is a neurotransmitter that human brains also use. I may have several hundred million times more neurons than a nematode, but as a biological organism I share fundamental commonalities with it. Standing in the corridor looking at the wormâs body plan, I thought of myself as a kind of snaky organism with limbs. As a vertebrate, I differ from a worm in that I have a backbone and a brain encased in a skull. But like a nematodeâand like most other animalsâthe bulk of my nerve cells is situated close to my mouth, and I have a long digestive tract. At the core of my being, there is a snakelike tube stretching from mouth to anus.
Nematodes eat bacteria that they find in the soil. All animals feed on other organisms. Even vegetarians prey on plants. You cannot eat a carrot without killing it. Whether a vegetarian diet of plants is more ethical than an omnivorous one is a matter of opinion. I know I am a predator.
Putting an end to my reverie, a woman walked up to me and introduced herself as a geneticist working with nematodes. Her