Xenology: An Introduction to the Scientific Study of Extraterrestrial Life, Intelligence, and Civilization
© 1975-1979, 2008 Robert A. Freitas Jr. All Rights Reserved.
Robert A. Freitas Jr., Xenology: An Introduction to the Scientific Study of Extraterrestrial Life, Intelligence, and Civilization, First Edition, Xenology Research Institute, Sacramento, CA, 1979; http://www.xenology.info/Xeno.htm
14.1.1 In the Beginning
The amoeba is one of the most primitive microorganisms on Earth today. In its own limited environment, it does quite well without any nervous system. The amoeba responds to chemical gradients and bits of food floating by, towards which it extends its pseudopods, engulfs, and consumes.
Another protozoan -- the paramecium -- is vastly more sophisticated by comparison. This animal is covered with a kind of "fur," a coating of tiny hairlike cilia growing from the outer wall of the single cell. As paramecia move through the water the tiny cilia beat in unison, coordinated by small filaments connecting the roots of the hairs. Each organism also has a ciliated mouth so that food may be fanned into the microscopic gullet.
While it has only the simplest of nervous systems, the paramecium does have a crude "memory." For instance, when it bumps into an obstacle, it has the ability to back up, turn slightly to one side, and move forward again. It can thus remember whether what it did last was wrong, and If so, it can correct the situation.
The sponge exemplifies the next stage in the evolution of multicellular intelligence on Earth. This organism is really just a colony of single-celled creatures with abilities similar to those displayed by paramecia. The hundred or so individuals in the collective manage to beat their cilia in the same general direction, thus setting up a flow of water and food for the benefit of all.
But there is no whole-body coordination -- a stimulus applied to one part of the animal causes only a local disturbance close to the site of application. Cells farther away are never informed of the problem, and do not react.
The hydra is probably the simplest terrestrial creature alive today with what is called "global coordination." If there is some noxious stimuli, the entire organism will bend away. It has a rudimentary "true" nervous system which permits impulses to traverse the entire body. But there is no brain, so the hydra is incapable of very sophisticated responses. It cannot pool a variety of stimuli, and it cannot really choose among alternative actions.
The development of early life, from simple reactivity in the amoeba to full global coordination in the hydra, seems fairly straightforward. If the Hypothesis of Mediocrity holds true and Earth is typically exotic, the evolution of whole-body coordination may be expected to be basically similar on other worlds.
But above the level of Hydra, evolutionary convergence begins to break down. According to the paleontological record, there is a fork in the road. The animal kingdom divides into two distinct classes representing wholly different stratagems for gaining increased intelligence.
Nearly a million animal species -- arthropods, molluscs, and many other in vertebrates -- opted for what paleoneurologists call the "ganglionic" nervous system. The earthworm is typical. Each of its many segments is almost an individual organism unto itself -- each having its own set of kidneys, muscles, sensors and so forth. Coordination is achieved by a thin latticework of nerve fibers crisscrossing the animal from side to side and lengthwise.
The ganglionic system resembles, more than anything else, a ladder with bulbous neural ganglia at each of the joints. The invertebrate organism thus is comprised of a collection of sub-brains, each of which controls a separate part of the animal with fairly complete autonomy. The organizational structure is not unlike that of a political confederation.
Sensors tend to cluster nearer the head. A brain of sorts -- enlarged ganglia -- accumulates there, but it isn’t a true brain as we understand the term. Perhaps it is better described as merely a large collection or bundle of separate ganglia. Nevertheless, such a nervous system proves to be highly efficient for getting quick response to stimuli. Each clump of nerve cells becomes "expert" as some particular function -- detecting and passing along sensory information, sweeping leg or wing in wide uniform arcs, opening and closing the jaws in slow munching motions during feeding, and so on. The entire system is orchestrated by "consultation" with the "chairmanship" of the bundle of ganglia concentrated in the head, but there is no real centralized control.
The ganglionic system has proved an enormous success on Earth. The invertebrates, representing perhaps 97% of all animal species alive today, have discovered a data processing technique adequate to ensure their survival. Information is processed fast enough and in sufficient quantities to enable ganglionic organisms to thrive and proliferate. If this is no measure of biological success, what is?
Might extraterrestrials develop extremely high intelligence using a ganglionic nervous system, by far the most common on this planet?
The chances are strongly against it.
Half an eon ago the invertebrates ruled the Earth. Huge trilobites crawled the shores, gigantic dragonflies with impressive wingspans patrolled the skies, and monstrous squids plied the oceans with little competition. But since that time, in all the hundreds of millions of years that have followed this period of early dominance, there has been virtually no improvement in the design. Why?
Evolutionary biologists have suggested several answers which are interesting from a xenobiological point of view. First, it is believed that the system simply is too complicated when it is scaled up in size. With more and more units, ganglia become inefficient, unwieldy, and bureaucratic. While invertebrates tend to be restricted to smaller sizes for unrelated technical reasons, it’s even true that large invertebrates of greater mass than vertebrates are not nearly as intelligent. For example, many lobsters are larger than squirrels, and many squids are vastly bigger than most vertebrates -- and yet these ganglionic creatures invariably are stupider kilogram for kilogram. The system itself appears to be at fault.
It has also been suggested that the ganglionic system is self-limiting. Typical invertebrate structure has only enough room to accommodate programmed "hard-wired" behavior, with no space left over for surplus neural matter that might eventually evolve and enlarge into higher intellect. Still another factor is that the endless cross-connections within the body can become so entangled and interwoven that they actually begin to strangle other body organs. A case in point in the spider, whose head ganglia happen to ring its gullet. But they have grown so massive that they squeeze the throat very tightly, and the poor animal can only swallow its food in a thin trickle.
It is hard for us to imagine the mentality of beings with ganglic intelligence. Dr. H. Chandler Elliot, Professor of Neurology at the University of Nebraska College of Medicine, describes the peculiar disconnectedness of the world-view of the invertebrates:
We humans usually disregard our internal organs: We suffer discomfort from an empty stomach, and we heed a stomach’s demands for relief of indigestion, but normally we disregard its activities. The head of an insect apparently regards not only its viscera but also its legs, wings, and so on, with similar detachment: If one deftly clips off the abdomen of a feeding wasp, the head may go on sucking, obviously not distressed. The mind of such a creature must be alien to us almost beyond comprehension.90
We come at last to the second distinct stratagem for achieving intelligence. A long time ago, a small band of daring organisms set out to explore a totally new system of neurological organization. The chordates (vertebrates plus a few others), who even today number only in the tens of thousands of species, began to experiment with "neural monarchy." As we shall see presently, this "central nervous system" is probably the intelligence of choice for sentient extraterrestrials even though it represents only a tiny percentage of all living animal species on Earth.
The flatworm (Planaria) was perhaps the earliest organism to advance beyond the simple nerve net of the hydra. With its primitive central nervous system, the flatworm can actually combine different types of stimuli and then act on this processed information. The animal has two eyespots, a pair of photosensitive cups which give it a curious cross-eyed look. Depending on which side is brighter, the flatworm wriggles away, for it fears the light. Olfactory sensors spread over the surface of its body can sense the smell of rotting meat -- a repast the flatworm heartily enjoys -- and off he goes in the direction of the scent. If contradictory input is received (the smell of rotten meat under a bright light) the organism is able to decide whether dinner is worth braving the intervening glare.
One of the first true chordates probably was the ancestor of the modern lancelet (Amphioxus), a small wormlike aquatic mud-dweller. Amphioxus takes the global coordination of hydra and the deductive ability of the flatworm and packs it all into a neat, centralized neural tube. Under dissection there appears to be little difference between brain and spinal cord. But the distinction is of fundamental significance.
The lancelet’s central nervous cord is vastly simpler than the ladder-like ganglionic system of the earthworm. Any number of additional sensory, analytical, or information-processing units may be plugged into the "central data bus." With this simple invention organisms could evolve to any size, yet continue to increase their intelligence simply by plugging in more "peripherals." The spinal column could grow into something far more massive than ganglionic nerve nets, yet never entangle or choke off other organs of the body. The simple brain was more compact and had plenty of room in which to expand. Over millions of years, it began to grow (Figure 14.1).
Figure 14.1 The Rise of the Brain in Terrestrial Biological Evolution
Dr. Elliot explains the evolutionary significance of this invention in the development of intelligence on Earth:
Thus our worm-fish ancestor could learn. As an individual, of course, he must have been an unteachable dolt, compared to whom a bee is a gifted scholar. But as a race, he and his descendants steadily added new resources to their bodies and brains for ages during which the bee was interminably repeating its perfected, dead-end patterns of living. Till finally creatures arose that could learn freely as individuals -- squirrels, cats, and men, who can expand their unified minds farther in an hour than a bee in all its year or two of life, and for many thousands of hours. Man, above all, aspires to worlds and universes of power and delight eternally closed to the bee. All this he owes to the original neural tube, simple but overwhelmingly more potent than the highest facile, flashy, self-limiting ganglionic system.90
If, as many comparative neurophysiologists now believe, the ganglionic or "distributed brain" is the wrong path for higher intelligence, then it is virtually certain that a great many extraterrestrial races in our Galaxy will have made the same momentous discovery during their long evolutionary trek. If ETs have discovered other alternatives to the ganglia and the central notochord, well and good. They would be fascinating to observe, because they would be without precedent on Earth. But we know that the path of the chordates is a sound one, and this is why we expect the idea of notochords and brains to be familiar to alien xenologists as well.
Last updated on 6 December 2008