Intelligence in Nature - Jeremy Narby [25]
I viewed pain as an experience humans probably share with animals. I have passed several gallstones, and know that pain has to do with the deep wiring of my body. I know just how paralyzing and excruciating it can be when raw nerves inside the body are scraped. Pain seems to be an undesirable experience one can have when one is equipped with a central nervous system. I knew nothing about pain among insects, but I figured that if their brains can handle abstraction, they can probably handle pain as well. I asked Giurfa if he thought bees feel pain. He said, âIf you hurt a muscle, then, yes, you hurt the animal, but if you just remove a bit of shell, you do not hurt it. So you can delicately expose the brain, by fastening the bee in a tube, and you can look at what is going on.â
Pointing at the map of the bee brain, he showed me the âolfactory pathway.â On the tip of a beeâs antennas are olfactory receptors (corresponding to the mucus membrane inside the human nose), which feed chemo-electrical information into nerves leading to two small grapelike structures at the base of the brain (similar in shape to our own olfactory bulb). From there, wirelike neurons lead to the mushroom body, which processes the different inputs.
Giurfa and his colleague Randolf Menzel recently described the âcognitive architecture of the honeybee minibrainâ as a network of independent units, the âmodules of an insect mind.â Each module treats information from a specific input, such as smell. The different inputs are then combined in a central locus, the mushroom body, where âcontext-dependent decisionsâ are reached. This enables honeybees to âextract the logical structure of the world.â
Bees go out into the world equipped with a tiny brain and learn about their environment in next to no time. They have a lifespan of only two or three weeks. They seem ready to learn as soon as they hatch.
Some of Giurfaâs graduate students were running an experiment next door. He suggested we go and check their work. I followed him out of his office and found three students sitting at a white table gathered around an odd-looking deviceâa blue metal plate with a copper cartridge sticking out of one end. A bee was strapped into the cartridge. An array of small tubes was directed at its face. The graduate student conducting the experiment held a toothpick in his hand. He explained that when the antenna of a hungry bee is touched by a toothpick dipped in sugared solution, a reflex always occurs, causing the bee to stick out its tongue in a jerk reaction comparable to the reflex of a knee hit by a hammer. Giurfa explained that one could present an odor immediately before the sugar reward, and teach the bee to form an association that, in subsequent tests, causes the odor, rather than the sweetened toothpick, to release the tongue. This shows bees can learn about smell; it also reveals which parts of their brains are active when they do so. Bees, it turns out, can detect odors with greater sensitivity than dogs.
I looked closely at the bee in the cartridge. It was strapped in with blue tape. It could only move its antennas and tongue. Its head was glued to the back of the tube.
I chatted for a while with the graduate students. They were from Germany and said, speaking in English, that they loved Toulouse, which is near the Mediterranean, the Pyrenees, and the Atlantic, all at once. But they said it was more difficult to concentrate on science here; in Berlin, where it was âgray and rainy all year,â they found it easier to work; here, they wanted to go on vacation all the time.
I focused once again on the bee. Spending an hour strapped in a bullet was a long time from a beeâs perspective. It did not seem very comfortable. I inquired about its fate after the experiment. Giurfa explained that the bees they tested in this fashion had to be killed, because otherwise they would return to the hive and falsify subsequent trials.
The bee I was observing