Re: Starthrower, by Loren Eiseley
Posted: Sun May 01, 2016 11:35 pm
The Ghostly Guardian
There is an animal that is followed everywhere by a ghost. The ghost floats uncannily a little above and just back of the animal's head. Whether the creature is clambering up the bars of a cage in the zoo or ascending trees in the dense rain forests of the Amazon or the Orinoco, the ghost is always there, sensitive, exploring, shrinking back or protruding forward as the occasion may demand.
The animal is a skinny creature in a funereal black dress. Its legs, arms, and tail are so elongated in proportion to its body that, seen obscurely through a curtain of leaves, it often appears like a huge and repulsive spider as it sidles about in the forest. As a result it has earned the name of "spider monkey," and the ghost that accompanies it is its tremendously lengthy tail. This tail is one of the most remarkable organs to be found anywhere among a group of animals, the monkeys, noted for their addiction to quite varied styles in posterior adornment.
The spider monkey's tail is prehensile -- that is, it is capable of grasping objects and transferring them to its owner's mouth, or of holding him safe while he is seated on a waving branch, or its almost preternatural grasping power may save his life as he hurtles headlong from some lofty spot in the forest attic. The muscles and nerves of such tails are of so extraordinary a character that even in death they may hold their owner to his aerial refuge after he has been slain by rifles from the ground.
The spider monkey's tail, however, is not the strangest part of the story. He lives in an area where a great variety of animals of quite unrelated ancestry have tails of this general type, although the spider monkey's is perhaps the most clever and appears to have almost literally taken on an independent life of its own. It is, in very truth, a guardian ghost, but the tail itself is not nearly so mysterious as the way in which numerous diverse creatures in one particular area of forest have acquired these hovering appendages.
These contemporaneous animals, all of one time and place but of widely different origins and habits, share in common one thing: the prehensile grasping tail. In a living world regarded by many scientists as the creation of chance mutations in animals acted upon by selective forces in the environment, they present a strange spectacle. These dangling creatures with their uncanny third hand suggest, inescapably, that nature, somewhere in the vast intricacies with which she complicates the world of life, has here been playing with loaded dice.
On the basis of pure chance it is hard to see why the mysterious evolutionary forces behind the universe should have bestowed this gift with such incredible profusion in only one area of the world, the Amazon basin. It is as though all human beings had spun coins at a particular moment but only those who tossed in San Francisco came up with "tails." This is an obvious simplification, but it makes the issue clear. We would regard such an event as outside the known laws of mathematics. We would feel a hair-raising chill down our spines and demand an explanation.
That is the way one feels when one looks at the ghostly guardian hovering behind a spider monkey, particularly when one walks to the next cage of the mammal house and sees Coendou, the prehensile- tailed porcupine of South America; or Disactylus, the pygmy anteater, "note the strongly prehensile tail." At such times, though I am supposed to be a naturalist and adjusted to such matters, I get the chill to which I referred. I slink out, almost as if I were followed by a tail myself, and go and sit on a bench to meditate upon the inscrutable way of tails in nature. Of six whole genera -- not species, but genera -- of South American monkeys, only one lacks a grasping tail. If you are not a student of these matters you may think indifferently, So what? All monkeys, you see cartoons of them everywhere, hang by their tails. It's the way of monkeys. But the "way of things" is a cover-up for our ignorance. As a matter of simple fact, there isn't a single solitary monkey on the continent of Africa who possesses a true prehensile tail. Yet many monkeys live lives in the high green attic of Africa that, so far as we can tell, are the precise equivalent of those lived by their relatives in the South American forests. But the monkeys of Africa climb without the help of their adorning tails, and as for other African animals only an obscure lizard and a peculiar scaled anteater, the pangolin, seem to be endowed with this helpful little secondary personality.
No, there is something else to be seen here than the "way of things," or, at least, the way of things turns out to be unaccountably marvelous whenever we turn sharply and begin to scrutinize it instead of using the phrase as an opiate. Involved in this matter of tails are some strange factors of inheritance and change which still trouble the modern scientist and over which philosophers have puzzled in vain. Only by climbing ourselves into that lofty world hung on the unstable rafters of strangling vines or by peering down at the wandering and uncertain waters that drench the forest floor in the season of floods can we expect to learn anything of the dark forces that created the grotesque little appendage which, in the spider monkey, may affectionately caress his fellows or faithfully sustain his broken body beyond the hour of death.
The basins of the Amazon and Orinoco rivers contain the largest untouched tropical rain forest left anywhere in the world. Here is the world of the past as it existed over much of the globe before the crawling continent-wide glaciers of the Age of Ice met and forced back, in million-year-long battles, the forces of the green. Now, harried by the fires and axes of man, forests are everywhere in the process of disappearance. Their last strongholds lie in the damp hot lands along the equator in Africa, in South America, in a few South Sea Islands, and in the remoter confines of Asia. In these areas, and particularly in the state of Amazonas in Brazil, man can move only along the waterways that pour under the great archways of the forest. He is still a puny shadow who, a few feet from the protecting river, may vanish without a trace. If he flies above that endless green expanse and falls, he will be as soundlessly engulfed as though he had gone down into the sea itself. For this world is a sea, a sea over whose swaying green billows pass the wind and the birds. Below, the depths are still. Nevertheless, there is life there, scampering wildly through orchid gardens high in the dim green forest garret, just as, below the waves of the sea, there is also life among the forests of the coral.
The forest floor of the great jungles can almost be compared to the abyssal depths of the sea. It is barren and dark and it receives the dead that fall from above. Few higher forms of life haunt its dim recesses. The real life of the rain forest lives among the rafters of a thousand-mile attic more than one hundred feet above the ground. Here, safely elevated above the floods that swirl over hundreds of miles of forest during the rainy season, the monkeys pass on their trembling pathways, serpents creep through networks of vines, brilliantly colored parrots shriek discordantly, and even frogs are born in aerial ponds and never go beneath their floor of leaves. In short, this is a world whose life needs the help of a friendly ghost, and among all the animals who creep and climb on rickety stairs and crumbling balustrades, tails are much in evidence. Not just any old tail, but tails that creep along behind and hold one safe. Tails with naked sensitive tips furrowed like fingers with nonskid whorls of skin.
In a place where death lurks frequently on either side of some quivering patchwork of cables it is no great marvel that everything from porcupines to arboreal anteaters should have a second life in their tails. The real mystery, to the student of tails, lies in another direction. It is the problem of how so many totally unrelated animals have acquired these tails in the Amazonian basin while in the great forests along the Congo scarcely a single aerial performer makes use of a prehensile tail. This is an uncanny situation. The dice of chance have fallen in a certain way all in one place.
The student of animal evolution is accustomed to the assumption that a series of chance changes in the heredity of an animal -- "mutations," the biologist calls them -- happen to promote the animal's welfare in a given way of life. Slowly, by infinitesimal degrees, such advantageous mutations may be followed by others until an animal is equipped with some highly improved organ such as a grasping tailor other useful character. All of this, as far as present-day experimentation can tell us, is the result of chance adaptations which are very infrequent compared with poor or disadvantageous variations that lead to an animal's destruction. Chance adaptation, in other words, might have readily explained the appearance of one species of monkey with a prehensile tail. It might even explain the occurrence of a grasping tail in two closely related forms, because closely related forms, possibly because of similarities in their body chemistry, may show a tendency to produce similar mutations and hence to evolve along the same pathway, particularly if their environment is such as to similarly select them. But here, in a single great jungle, numerous quite unrelated animals have all chosen to pull out of the grab bag of chance a single useful organ: the grasping tail. Within a reasonably limited period of geological time, they have drawn from the mysterious little packets of the genes, the hereditary substance, an identical solution to a similar problem, and supposedly it has been done by chance variation and selection.
"Easy," runs one solution. "Tails all tend to vary in this direction. It's one of the few useful ways they can vary. Nothing to it."
If one says this, one is forced to look at the arboreal life of Africa. The minute one does so the ease of this solution slips away. There are many tails; among the African mammals there are no prehensile ones save that of the scaled and ancient pangolin. If the grasping tail has been so easy to produce by chance, why is it so scarce in Africa and so common in South America?
One writer, confining himself discreetly to monkeys, argues that the South American forms like the spider monkey are thumbless; as a consequence they have developed the prehensile tail as a compensation for this absence of a digit. Very well, but the colobus monkeys of Africa are thumbless and they do not possess a grasping tail. The correlation does not seem to hold, and in any case it does not explain why certain arboreal opossums, kinkajous, and other queer Amazonian beasts with paws and no missing digits should go in for grasping tails.
Another suggestion is that the Amazonian lowlands, being frequently inundated by floods, have stimulated the selection of prehensile tails more vigorously than the African forests. In this connection one must consider the Uakari monkey. He is a queer little fellow with an absolutely bald head and a choleric, equally bald face. Un- cannily human in facial appearance, he looks, in his coat of motheaten brown fur, as though he were a human being who had been playing an orangutang at a masked ball and had just removed his head mask. He has a nonprehensile, stumpy, rudimentary, and almost useless tail, but he continues to flourish happily among the Amazonian floods.
In any case it is to be noticed that while these varied theories attempt to explain the selection of mutations leading to the development of grasping tails, none of them really comes to grips with the more formidable problem of why these apt variations were all conveniently at hand in this one place. The difficulty is enhanced by the presence of such a diverse array of creatures all showing the same characteristic, which comprises several lesser adaptations such as suitably flattened vertebrae, muscular enhancement in the tail and lower back, a certain way of rolling up or manipulating the organ, and its control by the brain.
Darwin, always troubled by such problems, used to speak of the mysterious and unknown laws governing these matters. Unlike many of his followers he had no illusions that he had solved all the mysteries of life and evolution. Reading his works one is often made aware of how that great mind hesitated painfully over much that his followers take for granted.
Once he expressed himself to the effect that the independent duplication of a single animal form, if proven for two separate areas of the world, might force him to entertain the possibility of some other explanation for evolution than that offered by chance mutations acted upon by natural selection. Strangely enough, these monkeys of South America offer an evolutionary problem very close to, though admittedly not identical with, the hypothetical case proposed by Darwin. These monkeys, while not totally identical anatomically with those of the Old World, are remarkably similar to them. In fact, only the sophisticated observer can recognize the differences. Yet the separation of these two monkey groups from each other is ancient, and no ancestral monkey remains connecting the Old World with the New are known by fossil hunters.
Instead, it is believed by many authorities that the New World and Old World monkeys have arisen as parallel developments from older pre-monkey forms, the lemurs, which were once spread over the whole region from Asia to South America. In this case, creatures of very similar brain, face, habits, and general appearance would have come into being in separate parts of the world from ancestors far below the monkey level. Such a development might suggest latent evolutionary powers not entirely the simple product of what we, in our ignorance of a better word, call chance. We are not in a position as yet to verify absolutely this interpretation of the separate origins of the Old and New World monkeys, but it is the most reasonable theory that we possess.
There is no doubt that this mystery would have intrigued the brooding mind of Darwin, particularly since one of the South American monkeys involved has a brain which in proportion to its body weight is larger than man's. Perhaps fortunately for us, however, Chrysothrix, the squirrel monkey, stayed small and remained in the trees so that his large and elflike cranium presents no threat to us. Yet withal, these strange parallelisms leave one with an odd feeling about what the biologist means by chance.
Elusive, tantalizing, and remote in the green attic of the elder world one catches an occasional glimpse of faces hauntingly like one's own and yet different, as though one peered into a charmed mirror. And slowly, through the shifting endless greenery, crawl the multitudinous things with tails, the tails that curl and hold, or wave forward like slender ghosts. There is something, particularly in a spider monkey's tail, that is too bold and purposeful to be easily called the product of simple chance. It floats there like a complete little personality. At least it may cause the true philosopher to pause hesitantly and ponder before he dismisses the universe as totally a world of chance.
There is an animal that is followed everywhere by a ghost. The ghost floats uncannily a little above and just back of the animal's head. Whether the creature is clambering up the bars of a cage in the zoo or ascending trees in the dense rain forests of the Amazon or the Orinoco, the ghost is always there, sensitive, exploring, shrinking back or protruding forward as the occasion may demand.
The animal is a skinny creature in a funereal black dress. Its legs, arms, and tail are so elongated in proportion to its body that, seen obscurely through a curtain of leaves, it often appears like a huge and repulsive spider as it sidles about in the forest. As a result it has earned the name of "spider monkey," and the ghost that accompanies it is its tremendously lengthy tail. This tail is one of the most remarkable organs to be found anywhere among a group of animals, the monkeys, noted for their addiction to quite varied styles in posterior adornment.
The spider monkey's tail is prehensile -- that is, it is capable of grasping objects and transferring them to its owner's mouth, or of holding him safe while he is seated on a waving branch, or its almost preternatural grasping power may save his life as he hurtles headlong from some lofty spot in the forest attic. The muscles and nerves of such tails are of so extraordinary a character that even in death they may hold their owner to his aerial refuge after he has been slain by rifles from the ground.
The spider monkey's tail, however, is not the strangest part of the story. He lives in an area where a great variety of animals of quite unrelated ancestry have tails of this general type, although the spider monkey's is perhaps the most clever and appears to have almost literally taken on an independent life of its own. It is, in very truth, a guardian ghost, but the tail itself is not nearly so mysterious as the way in which numerous diverse creatures in one particular area of forest have acquired these hovering appendages.
These contemporaneous animals, all of one time and place but of widely different origins and habits, share in common one thing: the prehensile grasping tail. In a living world regarded by many scientists as the creation of chance mutations in animals acted upon by selective forces in the environment, they present a strange spectacle. These dangling creatures with their uncanny third hand suggest, inescapably, that nature, somewhere in the vast intricacies with which she complicates the world of life, has here been playing with loaded dice.
On the basis of pure chance it is hard to see why the mysterious evolutionary forces behind the universe should have bestowed this gift with such incredible profusion in only one area of the world, the Amazon basin. It is as though all human beings had spun coins at a particular moment but only those who tossed in San Francisco came up with "tails." This is an obvious simplification, but it makes the issue clear. We would regard such an event as outside the known laws of mathematics. We would feel a hair-raising chill down our spines and demand an explanation.
That is the way one feels when one looks at the ghostly guardian hovering behind a spider monkey, particularly when one walks to the next cage of the mammal house and sees Coendou, the prehensile- tailed porcupine of South America; or Disactylus, the pygmy anteater, "note the strongly prehensile tail." At such times, though I am supposed to be a naturalist and adjusted to such matters, I get the chill to which I referred. I slink out, almost as if I were followed by a tail myself, and go and sit on a bench to meditate upon the inscrutable way of tails in nature. Of six whole genera -- not species, but genera -- of South American monkeys, only one lacks a grasping tail. If you are not a student of these matters you may think indifferently, So what? All monkeys, you see cartoons of them everywhere, hang by their tails. It's the way of monkeys. But the "way of things" is a cover-up for our ignorance. As a matter of simple fact, there isn't a single solitary monkey on the continent of Africa who possesses a true prehensile tail. Yet many monkeys live lives in the high green attic of Africa that, so far as we can tell, are the precise equivalent of those lived by their relatives in the South American forests. But the monkeys of Africa climb without the help of their adorning tails, and as for other African animals only an obscure lizard and a peculiar scaled anteater, the pangolin, seem to be endowed with this helpful little secondary personality.
No, there is something else to be seen here than the "way of things," or, at least, the way of things turns out to be unaccountably marvelous whenever we turn sharply and begin to scrutinize it instead of using the phrase as an opiate. Involved in this matter of tails are some strange factors of inheritance and change which still trouble the modern scientist and over which philosophers have puzzled in vain. Only by climbing ourselves into that lofty world hung on the unstable rafters of strangling vines or by peering down at the wandering and uncertain waters that drench the forest floor in the season of floods can we expect to learn anything of the dark forces that created the grotesque little appendage which, in the spider monkey, may affectionately caress his fellows or faithfully sustain his broken body beyond the hour of death.
The basins of the Amazon and Orinoco rivers contain the largest untouched tropical rain forest left anywhere in the world. Here is the world of the past as it existed over much of the globe before the crawling continent-wide glaciers of the Age of Ice met and forced back, in million-year-long battles, the forces of the green. Now, harried by the fires and axes of man, forests are everywhere in the process of disappearance. Their last strongholds lie in the damp hot lands along the equator in Africa, in South America, in a few South Sea Islands, and in the remoter confines of Asia. In these areas, and particularly in the state of Amazonas in Brazil, man can move only along the waterways that pour under the great archways of the forest. He is still a puny shadow who, a few feet from the protecting river, may vanish without a trace. If he flies above that endless green expanse and falls, he will be as soundlessly engulfed as though he had gone down into the sea itself. For this world is a sea, a sea over whose swaying green billows pass the wind and the birds. Below, the depths are still. Nevertheless, there is life there, scampering wildly through orchid gardens high in the dim green forest garret, just as, below the waves of the sea, there is also life among the forests of the coral.
The forest floor of the great jungles can almost be compared to the abyssal depths of the sea. It is barren and dark and it receives the dead that fall from above. Few higher forms of life haunt its dim recesses. The real life of the rain forest lives among the rafters of a thousand-mile attic more than one hundred feet above the ground. Here, safely elevated above the floods that swirl over hundreds of miles of forest during the rainy season, the monkeys pass on their trembling pathways, serpents creep through networks of vines, brilliantly colored parrots shriek discordantly, and even frogs are born in aerial ponds and never go beneath their floor of leaves. In short, this is a world whose life needs the help of a friendly ghost, and among all the animals who creep and climb on rickety stairs and crumbling balustrades, tails are much in evidence. Not just any old tail, but tails that creep along behind and hold one safe. Tails with naked sensitive tips furrowed like fingers with nonskid whorls of skin.
In a place where death lurks frequently on either side of some quivering patchwork of cables it is no great marvel that everything from porcupines to arboreal anteaters should have a second life in their tails. The real mystery, to the student of tails, lies in another direction. It is the problem of how so many totally unrelated animals have acquired these tails in the Amazonian basin while in the great forests along the Congo scarcely a single aerial performer makes use of a prehensile tail. This is an uncanny situation. The dice of chance have fallen in a certain way all in one place.
The student of animal evolution is accustomed to the assumption that a series of chance changes in the heredity of an animal -- "mutations," the biologist calls them -- happen to promote the animal's welfare in a given way of life. Slowly, by infinitesimal degrees, such advantageous mutations may be followed by others until an animal is equipped with some highly improved organ such as a grasping tailor other useful character. All of this, as far as present-day experimentation can tell us, is the result of chance adaptations which are very infrequent compared with poor or disadvantageous variations that lead to an animal's destruction. Chance adaptation, in other words, might have readily explained the appearance of one species of monkey with a prehensile tail. It might even explain the occurrence of a grasping tail in two closely related forms, because closely related forms, possibly because of similarities in their body chemistry, may show a tendency to produce similar mutations and hence to evolve along the same pathway, particularly if their environment is such as to similarly select them. But here, in a single great jungle, numerous quite unrelated animals have all chosen to pull out of the grab bag of chance a single useful organ: the grasping tail. Within a reasonably limited period of geological time, they have drawn from the mysterious little packets of the genes, the hereditary substance, an identical solution to a similar problem, and supposedly it has been done by chance variation and selection.
"Easy," runs one solution. "Tails all tend to vary in this direction. It's one of the few useful ways they can vary. Nothing to it."
If one says this, one is forced to look at the arboreal life of Africa. The minute one does so the ease of this solution slips away. There are many tails; among the African mammals there are no prehensile ones save that of the scaled and ancient pangolin. If the grasping tail has been so easy to produce by chance, why is it so scarce in Africa and so common in South America?
One writer, confining himself discreetly to monkeys, argues that the South American forms like the spider monkey are thumbless; as a consequence they have developed the prehensile tail as a compensation for this absence of a digit. Very well, but the colobus monkeys of Africa are thumbless and they do not possess a grasping tail. The correlation does not seem to hold, and in any case it does not explain why certain arboreal opossums, kinkajous, and other queer Amazonian beasts with paws and no missing digits should go in for grasping tails.
Another suggestion is that the Amazonian lowlands, being frequently inundated by floods, have stimulated the selection of prehensile tails more vigorously than the African forests. In this connection one must consider the Uakari monkey. He is a queer little fellow with an absolutely bald head and a choleric, equally bald face. Un- cannily human in facial appearance, he looks, in his coat of motheaten brown fur, as though he were a human being who had been playing an orangutang at a masked ball and had just removed his head mask. He has a nonprehensile, stumpy, rudimentary, and almost useless tail, but he continues to flourish happily among the Amazonian floods.
In any case it is to be noticed that while these varied theories attempt to explain the selection of mutations leading to the development of grasping tails, none of them really comes to grips with the more formidable problem of why these apt variations were all conveniently at hand in this one place. The difficulty is enhanced by the presence of such a diverse array of creatures all showing the same characteristic, which comprises several lesser adaptations such as suitably flattened vertebrae, muscular enhancement in the tail and lower back, a certain way of rolling up or manipulating the organ, and its control by the brain.
Darwin, always troubled by such problems, used to speak of the mysterious and unknown laws governing these matters. Unlike many of his followers he had no illusions that he had solved all the mysteries of life and evolution. Reading his works one is often made aware of how that great mind hesitated painfully over much that his followers take for granted.
Once he expressed himself to the effect that the independent duplication of a single animal form, if proven for two separate areas of the world, might force him to entertain the possibility of some other explanation for evolution than that offered by chance mutations acted upon by natural selection. Strangely enough, these monkeys of South America offer an evolutionary problem very close to, though admittedly not identical with, the hypothetical case proposed by Darwin. These monkeys, while not totally identical anatomically with those of the Old World, are remarkably similar to them. In fact, only the sophisticated observer can recognize the differences. Yet the separation of these two monkey groups from each other is ancient, and no ancestral monkey remains connecting the Old World with the New are known by fossil hunters.
Instead, it is believed by many authorities that the New World and Old World monkeys have arisen as parallel developments from older pre-monkey forms, the lemurs, which were once spread over the whole region from Asia to South America. In this case, creatures of very similar brain, face, habits, and general appearance would have come into being in separate parts of the world from ancestors far below the monkey level. Such a development might suggest latent evolutionary powers not entirely the simple product of what we, in our ignorance of a better word, call chance. We are not in a position as yet to verify absolutely this interpretation of the separate origins of the Old and New World monkeys, but it is the most reasonable theory that we possess.
There is no doubt that this mystery would have intrigued the brooding mind of Darwin, particularly since one of the South American monkeys involved has a brain which in proportion to its body weight is larger than man's. Perhaps fortunately for us, however, Chrysothrix, the squirrel monkey, stayed small and remained in the trees so that his large and elflike cranium presents no threat to us. Yet withal, these strange parallelisms leave one with an odd feeling about what the biologist means by chance.
Elusive, tantalizing, and remote in the green attic of the elder world one catches an occasional glimpse of faces hauntingly like one's own and yet different, as though one peered into a charmed mirror. And slowly, through the shifting endless greenery, crawl the multitudinous things with tails, the tails that curl and hold, or wave forward like slender ghosts. There is something, particularly in a spider monkey's tail, that is too bold and purposeful to be easily called the product of simple chance. It floats there like a complete little personality. At least it may cause the true philosopher to pause hesitantly and ponder before he dismisses the universe as totally a world of chance.