Science: Insects, Animals, and Man
At mating periods a male mosquito vibrates its wings at a specific frequency, analogous to a wolf whistle, while the female (if favorably inclined) whistles back, also at a certain frequency. The pair can hear each other’s tiny sounds at distances of 150 feet, and over such conflicting noises as wind, the louder buzzing of other insects, humming power lines, and factory whistles.
This remarkable achievement, an example of what sound experts call “wave form,” has interested a number of industrial researchers, including scientists at Lockheed Aircraft Corporation, who think the mosquito can teach us something new and important about “communication,” a magic word in the modern universe of applied science.
This is only one example of a rapidly growing body of research based on our realization that insects, as well as snakes and fish, the porpoise and its relatives, and even worms, can perform mysterious acts that even our most intricate electronic machines cannot.
According to a Natural Science Foundation estimate, more than 20,000 biologists are at work in corporate research laboratories. Although not all these studies are centered on insects, there is a special satisfaction for electronic scientists, computer experts, and cyberneticists in this animal class, since the insects have (perhaps mistakenly) been regarded as very close to reflex machines.
Insects are especially expert at sounds and odors. The reaction of houseflies to sounds is a weird case in point. The noise of an exploding firecracker will not faze the fly, but he is repelled by the almost inaudible sound of a rubber stopper turning in a bottle. Certain moths drop to the ground when they hear the ultrasonic cry of a bat, a natural predator. Insects’ reactions to odors are incredibly delicate and discriminating. The aeronautic division of Ford Motor Company is trying to develop chemical imitations of the insect olfactory organs for use as detectors of toxic gases. The antenna nerves and olfactory lobes of green bottle flies are removed and outfitted with electric probes hooked up to oscilloscopes, so that when they react to traces of chemicals in the air, a sharp wave is seen on a screen.
From the standpoint of the entomologist interested in controlling insects, the fact that insects rely on sexattractant odors is a useful means of experimental exploitation. Having identified the attractant chemical, the entomologist saturates the insects’ whole environment with it. The male insect cannot zero in on any female insect since he is apparently surrounded by innumerable but elusive females, and the result is deadly frustration.
Is there anyone inside?
This points up a controversial argument among scientists. Do insects, after all, have emotions, perhaps even Freudian complexes? If so, it would be a great disappointment to the electronics people. Professor Vincent G. Dethier of the University of Pennsylvania has suggested that it is not true that insects are little machines in a deep sleep. Looking at their rigidly armored bodies, their staring compound eyes, and their mute performances, the professor cannot help wondering at times if there is “anyone inside.” Sharp rebukes to such musings have come from other professors, who argue that about half a billion years ago the insects went their way and we went ours. No parallel involving such warm-blooded activities as emotions and thinking can be drawn. The insect brain is totally dissimilar, aside from sheer mass. (The brain of the culicid midge, or no-see-um, is about the size of a particle of smoke.) What corresponds to our cerebrum in insects is located ludicrously on the outside, and up to 80 percent of the total brain is occupied by nothing but optic lobes.
Nevertheless it seems certain that insects succumb to frustrations so intense that they literally commit suicide. If one imprisons a hive-bound honey bee in a glass cage, it will die because of mental stress. Moreover, this frustration occasioned by taking wing and being suddenly stopped is “catching.” Small quantities of hemolymph (“blood”) from one frustrated bee placed on the stinger of a happy bee will cause the latter to go into spasms and die. Yet the frustrated bees can be quickly pacified by the mere presence of a small piece of empty honeycomb from the bees’ home.
It is because of such suspicious indications of nervous instability that applied scientists are less interested in bees now than in less temperamental flying creatures. They have long since solved the famous problem of how a bumblebee can fly in spite of its tiny wings and swollen fuselage.
What interests many of the electronic engineers are certain incredible abilities of snakes and fish. Air Force scientists have found that the rattlesnake is equipped with a kind of receptor that can distinguish objects differing in temperature by one thousandth of a degree Centigrade. This is better than most of the very expensive man-made thermostatic control devices. When two balls of equal size but distinguished from each other by this small fraction of a degree in temperature are presented to the snake, it will invariably and unhesitatingly strike at the warmer ball. The Air Force would like to know how the snake does this, since our most potent airto-air missile is the Sidewinder, which is led to its target by heat radiation. The Sidewinder, however, can be fooled by decoys roughly the same temperature as the engine or rocket exhaust and which are launched from the target vehicle. It would presumably be impossible to fool an intelligent flying rattlesnake.
Still more mystifying are the electric receptors of certain fish (such as gymnarchus) which can detect obstacles at sunless depths by a sort of low-frequency radar. These fish emit pulses of low voltage with frequencies characteristic of each species, ranging from 50 to 1600 cycles per second. The change of the pattern of the electric field as a result of objects, apertures, or other fish in the surrounding water is detected by gymnarchus. So incredibly sensitive is this response that these creatures will respond to the movement of an electrostatic charge produced by waving a comb that has been run through one’s hair outside the aquarium. They can even tell when someone approaches the aquarium carrying a small stationary magnet in his pocket. It has been calculated that these fish are sensitive to a change in electrical field of the water of three billionths of a volt per millimeter, a fantastically minute alteration very difficult to detect by even the most sensitive man-made instruments.
This business of detection under water is naturally of great concern to the Navy, since one of its most crucial problems is antisubmarine warfare. This is primarily why the Navy is so interested in porpoises and whales, because of their advanced sonar capabilities (the sound equivalent of radar). The public seems a bit bored with the porpoise and other aquatic mammals because they have received so much publicity, but this boredom does not extend to the Navy, which has only recently become aware of an extraordinary Russian program during World War II in which seals were trained to cut underwater cables with clipper mechanisms attached to their heads.
The Navy finds that the porpoise can emit sonar signals ranging from 450 to 190,000 cycles per second and can locate schools of fish up to 8000 yards. The sea lion is another very sophisticated sonar operator. The shark is not far behind, although he operates by a so-called “passive” system, relying on sound sent out by the target rather than on vibrations emitted and reflected, as is the case with the porpoise and seal. The shark’s long-range sensing organs seem to be located along his sides rather than in his ears, which are inside the cranium.
All these marine animals appear to have a sound-sensing capability superior to man’s sonar instruments in one critical respect. Submarine detection signals are deflected at the meeting place of warm and cold water layers. An enemy sub lying in the right spot would be “invisible” to us, and there are a lot of such hiding places of warm water surrounded by cold water. The sea animals do not seem to be baffled by these situations.
Another problem of antisubmarine warfare is how to make faster torpedoes. The Navy is not releasing details on its highly classified “Mark 45” torpedo carrying a nuclear warhead, but it has long been admitted that the practical upper limit to a torpedo’s speed is about 30 knots, and this limit is set by water resistance rather than motor power. The well-documented speeds of the fastest sea animals include 70 knots for the sailfish and 50 knots for the swordfish. How do they do it?
Hydrodynamic authorities such as those at the U.S. Naval Ordnance Test Station believe that the most important factor is “body participation,” which in technical language creates a “propeller race” in exactly the same location as the “hull wake,” thus “wiping the wake” (eliminating the water resistance caused by eddies). Marine animals such as the porpoise and whale, with top speeds of 30 knots or more, propel themselves by waving their tails rather than undulating their bodies, as fish do; hence their speed problem is closer to that of the torpedo. It appears that the skin of porpoises and whales is attached to the underlying layer of blubber in such a way that the living animal can cause the water to flow by him in streamlines of low resistance. Hydrodynamic experiments show that a dead animal causes only normal friction. But research to duplicate the living skin with the use of silica gel layers and other expedients has so far given doubtful results.
Getting around the bends
This new approach to animals has caused a good deal of fussing among some of the old-style zoologists who are not interested in considering their pet subjects as patterns for torpedoes and missiles but who have often failed to explain relatively simple phenomena in their closely guarded areas of expertise. The science of whales, for example, is an old one, but for decades the experts in this branch of zoology could not explain why whales fail to get the “bends” when they surface after sounding to great depths.
It took a latter-day mechanical engineer to come up with the solution, which was so absurdly simple, yet so persuasive, that it had to be accepted: when a deep-sea diver is submerged, air is pumped to him at high pressure. Thus his body is exposed to a constantly renewed supply of nitrogen.
When a whale sounds, on the other hand, he has only to dispose of the relatively insignificant amount of nitrogen that he takes down with him in his surprisingly small lungs. If you put a whale in a diving suit and pumped air to him at the ocean depths, he would get the bends too.
In the field of optics, which is hugely important in computers for guided missiles and space flight, we go to the birds or to the frog.
The frog has a peculiar optical system in that it sees only what it has to see. If it is after a deerfly, for example, only the pattern of the fly, its distance, and its detailed movements register on the frog’s consciousness. All extraneous visual data are immediately shut from its brain. This is a very instructive kind of behavior for data-processing computers. RCA has recently been able to duplicate the frog’s eye in a complex layered array of lightsensitive photocells.
Animal brain trust
Douglas Aircraft’s Astropower Laboratory, on the other hand, has specialized on the pigeon’s eye. Like most birds, the pigeon has remarkable long-distance vision but combines with this the frog’s ability to pre-process certain information in its retina. Both the frog and the pigeon receive, so to speak, a translated version of what their eyes see. This is unlike the more roundabout vision of man, where the brain has to do the translating.
Of special interest is the pigeon’s ability to detect within its complicated retina the motion of an object in a single direction, a characteristic called directional movement detection. Applied to a man-made surveillance radar, this ability would be of incalculable value for automatic defense monitoring systems.
The brains of animals have recently been researched in tremendous detail with the hope of getting some notions for computer designs of greater versatility. At the University of California the biologically crucial discovery has just been made that the brains of mature mice can be encouraged to grow in weight and complexity by training the animals to solve problems.
Some engineers are impatient and suggest the use of animal brains currently as parts of complex operating circuits. It has even been proposed to put a cat’s brain in a missile in order to guide it to a target. The ability of birds to discriminate among land patterns (the presence and identity of cities, fortifications, missile launch sites) would be used, in one approach, by training birds to peck at the right button inside a missile, thereby zeroing the weapon in when the correct target is recognized. This was, in fact, suggested to the military by Professor B. F. Skinner as long ago as 1939.
Although a belief in pragmatic, not to say brutal, utilization of the marvelous capabilities of animals, developed by nature through millions of years of evolution, is the predominant trend among the new breed of applied biologists, it is not a solely barbaric point of view. We can expect to retrieve some clear and warm insight into these fascinating lesser creatures with which we share the planet. Through them we may hope to learn more about what we may see someday on other worlds. What we see out there ultimately will, in Aldous Huxley’s famous words, “sear the eyeballs.”
— Donald E. Carr
Douglas Kiker, the ATLANTIC’S Washington correspondent, is also on NBC’s capital staff. Don Cook is the Paris bureau chief for the Los Anqeles TIMES. Donald Carr is a research chemist and author of DEATH OF THE SWEET WATERS, published last year. In future issues, as in this one, some reports will be unsigned at the request of their authors. The ATLANTIC, of course, assumes responsibility for them.