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In the study of fasting it is necessary that we approach the subject from many angles. Perhaps no subject is less understood by the public and the "healing" professions than this oldest of means of caring for the sick body.
We are justified in studying every phenomenon which may throw light upon the subject and thus enable us to better apply the fast in our dealings with the sick. The fasting habits of man and animals are all legitimate objects of study. Not alone the fasting practices of sick animals, but fasting in healthy animals, whether voluntary or enforced, will aid us in more clearly understanding this subject. Particularly will such a study aid us in overcoming our cultivated fear of fasting. Hence the following studies.
The more one attempts to find out about the habits and modes of living of animals, the more one is impressed with the paucity of our dependable accumulated knowledge of the animal kingdom. Our biologists seem to be more intent upon classification than upon the important phases of life. If they study an animal, they prefer to kill it and dissect it, perhaps to mount it and place it in a case. They are more intent upon a study of death than of life. All unconsciously, perhaps, they have converted biology into necrology. I have, however, after much searching, succeeded in accumulating a considerable amount of material about the fasting habits of many animals. This I here propose to discuss under its various heads, as I have classified it.
That some animals fast during the mating season is well known, but our knowledge of the living habits of the animal kingdom is so meager that it is not known how many animals do so. So far as it is at present known, fasting during the breeding season is very rare among mammals and birds. Among mammals where there is keen competition between the males for possession of the females, feeding is curtailed, but this is hardly a fast.
Quite a number of fishes fast during the breeding season, the female of the Cichlidae, or mouth breeders, must fast at this time.--See History of Fishes, by J. R. Norman. The best known example of fasting by fish during the mating season is that of the long fast of the male salmon. Prof. Morgulis describes in these words, the annual fast of the salmon: "At the time they commence to migrate from the sea towards the streams, their muscles are thoroughly encumbered with huge masses of fat. Fasting all their journey, which lasts many weeks and months, they are in a much emaciated condition when they get to the upper reaches of the rivers where the currents are rough and swift. Freed from the fat, however, their muscles are now agile and nimble, and it is at this time that the salmon displays the marvellous endurance and skill admired by all sportsmen, in progressing steadily against all odds of the tumultuous current, waterfalls and obstructions."
Penguins and the male goose are the only birds I find mentioned as fasting during the mating season. The gander loses about one-fourth of his body-weight during this period. George G. Goodwin, Associate Curator, Department of Mammals, The American Museum of Natural History, New York, says: "It is questionable if any of the birds are capable of a prolonged fast--their rate of metabolism is too high. I have never heard that a gander fasted during the mating season and am inclined to question such a statement."
The basis of his questioning is not very solid; he has never heard of it. It may be assumed that if it were true he would have heard of it, but no man knows everything in biology and this is out of his special field. The other part of his objection, the high rate of metabolism of birds, is no basis at all. It only reveals that he knows little of fasting. It is not likely that the rate of metabolism of the male salmon is low while he swims hundreds of miles up-stream. His a priori doubts must be considered, they are not to be taken as final.
The Alaskan fur seal bull is the best known example of fasting by a mammal during the mating season. I have no information on the rate of metabolism in this mammal, but I think we are safe in assuming that, since he is a warm blooded animal and, at the same time, extremely active during the whole of the fasting period, his metabolic rate is high. During the entire three months breeding season of each year, the Alaskan fur seal bull does not eat nor drink (although within easy reach of abundant food) from May or the middle of June to the end of July or early days of August. After fighting for his place on the shore and for his harem of from five to sixty females, the male seal spends the summer fighting to keep his harem together and to keep his girls satisfied. Ray Chapman Andrews says, in his End of the Earth; "All through the summer he neither eats nor sleeps. It is just one long debauch of fighting and love-making and guarding his harem against unscrupulous invaders."
As a result of all this activity, Mr. Andrews says that "by September he is a wreck of his former self. All his fat has disappeared, for that is what he has been living on by absorption all summer. His bones protrude, his side is torn and scarred, he is weary unto death. Blessed sleep is what he needs. Forsaking his harem, he waddles back into the long grass far away from the beach, there to stretch out in the warm sun. He will sleep for three weeks on end without waking, if undisturbed."
After long months of incessant physical and sexual activity, without food, the seal thinks first of rest and sleep. Food may be had after the long sleep. With man, also, despite popular prejudices to the contrary, there are times when rest is of more importance than food.
The sea lion also fasts during the mating season. Although less tempestuous, the domestic life of the sea lion is described as being very similar to that of the fur seals. Coming ashore sometime between the middle of May and early June, the summer is spent in fasting and sexual activities. By the end of summer, the master of the harem is exhausted and has lost much weight, but is still able to wearily slip down the sloping beach into the sea, where a few months of fat living restore his emaciated form. The exertions of these sea lions, both sexual and physical, as they fight much, is described as tremendous. I have no information as to whether they, like the fur-seal bull, go without water during this period.
What may be regarded as fasting during the mating season is the phenomenon seen among many insects which have but a short adult life. The caterpillar does little else than eat. In certain species, after it becomes a butterfly, it never eats at all. Fabre showed that some insects have no provision for hunger, the digestive organs being absent in the fullest developed insects. Perhaps such short-lived species as ephemera should not be considered in this connection. These insects come into the world in the evening, mate, the female lays her eggs and by morning both sexes are dead without ever having seen the sun. Destined for little else than reproduction, they have no mouths and do not eat, neither do they drink. But the peacock butterfly, which often travels for miles in search of a mate and lives for a few days, though it has the merest semblance of a digestive apparatus, does not eat. The insect world presents us with many examples of this kind.
The pupal stage of insects which undergo metamorphosis, is that immediately following the larval stage. The term chrysalis has almost the same value as pupa. If the insect is not wholly quiescent during this pupal stage the word nymph is used. Since the larval stage of most insects differs so markedly from the adult stage, the pupal stage constitutes the intermediate stage in which the necessary bodily changes are effected. It is a period of internal transformation, during which most pupa are outwardly quiescent, they move very little, and do not eat at all. The marvellous structural and functional transformations take place during this period of abstinence from food, the pupa depending entirely upon its stored reserves for the accomplishment of its structural revolution. Pupal sleep may be artificially prolonged.
Fasts of longer or shorter durations are seen in many animals immediately after birth. For example, Fabre tells us that certain spiders eat no food for the first six months of their lives, but feast upon sunbeams. Chickens take neither food nor water for the first three days after they hatch from the egg. In most mammals there is no milk secreted for three or more days after their young are born. The fluid, secreted during this period is devoid of food value.
Many animals normally go for long periods between feedings, not eating for the reason that they are not hungry. For example, there are many snakes that eat only at long intervals.
An animal will refuse food when angry or excited. Indeed, an animal that is hungry and in the process of eating may be angered and will cease eating. Angry animals do not resume eating again until their anger has subsided. Reports of dogs grieving over the absence or death of their owners, refusing food for long periods, are often carried by the press.
Some animals refuse to eat when held in captivity. They will starve to death rather than live as captives thus making good Patrick Henry's ringing cry: "Give me liberty or give me death." One of these is the famous marine iguana, Amblyrhymchus Cristatus, a seashore lizard, of the Galapagos Islands, described as the "Vegetarian dragon" and "Fasting man." The Iguana feeds on sea-weeds and can abstain from food for long periods--over a hundred days.
Many thousands of animals of all kinds have been employed in experimental fasts. Insects, fishes, snakes, birds, rodents, rabbits, badgers, cows, horses, and many other types of animals have been used in fasts of varying lengths of time. In many of these fasts, the period of abstinence from food has been extended far beyond the normal limit of the fast into the period of starvation, some of them being ended before death occurred, others being carried on to death. While we are opposed to the suffering caused in animals by pushing the period of abstinence beyond the return of hunger, it has been done and the information thus obtained is available, and we are at liberty to make use of it in our studies of the subject. Many of these experimental fasts will be referred to as we proceed in our study.
Biologists, physiologists and research workers of all kinds are very fond of animal experimentation. But all of these workers are in the habit of ignoring important parts of the regular activities of animals. For example, they ignore, never mention, in fact, the numerous instances of dogs and other animals having fasted ten, twenty or more days when they, have received internal injuries or a broken bone. That a sick animal refuses food is well known to all laymen, but physiologists and biologists seem to think that this fact is unworthy, even, of mentioning. Can we not learn from observing the normal and regular activities of animals living normal lives--must we assume that animals are capable of teaching us something only when under artificial conditions, and subjected to processes that they never encounter in the normal course of their existence?
Dr. Oswald tells of a dog that had been put into the loft of a barn by the sergeant of a cavalry regiment. Losing its balance, while in the door of the loft and barking, it fell, turning a few somersaults as it came down, and landed on the hard pavement, "with a crack that seemed to have broken every bone in his body." He says "blood was trickling from his mouth and nose when we picked him up, and the troopers advised me to 'put him out of his misery,' but he was my little brother's pet, and, after some hesitation, I decided to take him home in a basket and give the problem of his care the benefit of a fractional chance. Investigation proved that he had broken two legs and three ribs, and judging by the way he raised his head and gasped for air, every now and then, it seemed probable that his lungs had been injured."
For twenty days and twenty nights the little terrier stuck to life in its cotton-lined basket without touching a crumb of solid food, but ever ready to take a few drops of water, in preference even to milk or soup. At the end of the third week it broke its fast with a saucerful of sweet milk, but only on the evening of the twenty-sixth day did it begin to betray any interest in a plateful of meat scraps.
Irwin Liek, noted German physician and surgeon, tells of instinctive fasting in three of his dogs. One of these had been run over by a truck which had broken several bones and injured it internally. The other had "devoured a considerable quantity of rat poison. It became very, very ill, suffered from diarrhea containing blood and pus" and "collapsed completely." The third lost an eye while "mixing it" with a cat. All three of these dogs fasted and recovered.
Physiologists have persistently ignored cases where dogs have voluntarily fasted for ten or twenty or more days when suffering from broken bones or internal injuries. Here is an action invariably pursued by nature which they persist in refusing to investigate.
It is said that the elephant, if wounded, and still able to travel, will go along with the rest of the herd and can be found supporting itself beside a tree while the remainder of the herd enjoys a hearty meal. The wounded elephant is totally oblivious to the excellent food all around him. He obeys an instinct as unerring as the one that brings the bee to his hive; an instinct which is common to the whole animal world, man included.
I need but devote little space to a discussion of what every one already knows; namely, that the sick animal refuses all food. The farmer knows that his "foundered" horse will not eat--is "off his feed," as he expresses it. The sick cat, dog, cow or other animal refuses food. Animals will abstain from food when sick for days and weeks, refusing all food that may be offered them until they are well.
Dr. Felix Oswald says: "Serious sickness prompts all animals to fast. Wounded deer will retire to some secluded den and starve for weeks together." Dr. Erwin Liek, endorses fasting and observes that "small children and animals, guided by an infallible instinct, limit to the utmost their intake of food if they are sick or injured."
Arthur Brisbane disapproved of fasting and took Mr. Sinclair to task for advocating it. After a lengthy correspondence about the matter, Mr. Brisbane acknowledged that "even dogs fast when they are ill." Sinclair retorted, "I look forward to the time when human beings may be as wise as dogs."
A dog or cat, if sick or wounded, will crawl under the wood shed or retire to some other secluded spot and rest and fast until well. Occasionally he will come out for water. These animals will, when wounded or sick, persistently refuse the most tempting food when offered to them. Physical and physiological rest and water are their remedies.
A sick cow or horse will also refuse food. The author has seen this in many hundreds of cases. In fact, all nature obeys this instinct. Thus does nature teach us that the way to feed in acute "disease" is not to do it.
Domestic cattle may often be found suffering from some chronic "disease." Such animals invariably consume less food than the normal animal. Every stockman knows that when a cow, or horse, or hog, or sheep, etc., persistently refuses food, or day after day consumes much less than normally, there is something wrong with that animal.
I need devote but little space to the fact that animals fast for shorter or longer periods in times of food scarcity when floods, droughts, storms, etc., destroy their food supplies, or when snow has covered their food and rendered it temporarily inaccessible. It often happens in the lives of animals that they are forced to go for days at a time without food for the reason that they cannot find it. They sometimes, though relatively rarely, perhaps, go so long without food that they die of starvation. Luckily, they possess sufficient reserves to enable them to go without food for prolonged periods and survive. Animals that enter the winter season with considerable fat, commonly emerge from winter rather thin due to the fact that they are forced to subsist on greatly reduced food supplies and often have to go for days at a time without food. Even at the height of the food season insects may so completely destroy the food supply that many animals are forced to go for considerable periods without food.
A number of accidental emergencies force both domestic and wild animals to fast at times. How frequently such accidents occur in nature, we are not in a position to say, but they are probably more frequent than we may suppose.
In his Curiosities of Instinct, Karl Vogt tells of the case of a spaniel which visitors had accidentally locked up in the attic of an old castle-ruin. The dog had been able to secure a few drops of water by gnawing the edge of a cleft in a slate covered roof. A few heavy rain-showers had supplied him with water, but he had had no food of any kind--no grain, leather, rats or mice--during the whole summer and part of the autumn. A picnic on the castle mountain during the first week in October resulted in his rescue by a wandering party of sight-seers. The ribs of the little prisoner; who had been locked up since the middle of June, could be counted as easily as in a skeleton, but he was still able to drag himself across the floor and lick the hands of his deliverers.
The following account of "Bum" appeared in Time for April 27, 1931: "When Joseph Carroll, engineer of a Brooklyn laundry, heard the Negro night watchman tell of a "ghost" he had heard one night last week, he walked into the engine room and straight to a boarded-up hole in the floor, relic of an unsuccessful well-digging. Stopping his ears, holding a knife in his teeth, he touched the knife to a pipe which went downward. Presently he could hear a distant moaning. "He knew what was in the hole. Early in January he had found and adopted a mongrel puppy. But after a few days the puppy, which he called 'Bum' disappeared. The same day, the hole over the excavation had been boarded up securely. The engine's noise must have drowned the dog's cries ever since.
"Hastily Engineer Carroll ripped up the board, descended, brought Bum, a skeletal dog, unable to stand alone, to the surface.
"No local veterinary would believe that a dog could have fasted for 14 weeks. Some thought Bum must have lived by rat-catching; some cried: 'Impossible'!"
Local veterinarians were as ignorant of fasting as was a medical man who once roundly scored a woman who had undertaken to fast, under my direction, after he and several of his big priced colleagues (specialists and medical professors) had declared they did not know and could not find out what her trouble was and could do nothing for her. He declared that if she went six days without food her heart would collapse and she would die.
She had two fasts, one of twelve days, the other of thirteen, and recovered her health. The doctor came crawling back some three months later and apologized for his ungentlemanly and unprofessional conduct. "I have been reading up on these cases and I find that in Germany they are using fasting in them with excellent success," he said.
An Associated Press dispatch from Warsaw, Ind., dated Dec. 31, 1931, tells of a sow surviving four and a half months without food. Buried under an avalanche of straw on the Oscar Rebman farm, east of Warsaw, on July 15, while threshing was in progress, she remained buried until Dec. 30, when workmen who were pulling out straw heard a grunt and were surprised to see the sow walk out minus about half of her former weight. This was a period of 168 days without food and water.
The "Great Blizzard of '49" was so terrible that many men, women and children and much livestock in the West froze to death. Many sheep froze around the haystacks. Unusually heavy snows fell and in some places remained for long periods. The snow was deep and animals were buried. Several reports of animals being buried deep in the snow for long periods were published. These are of special interest to us here, for the reason that these buried animals were deprived of food and of all possibility of obtaining food by the snow that covered them.
An Associated Press dispatch from Rapid City, S. D. tells of a pig found fifty-four days after the blizzard in that state. The dispatch says that before the blizzard of Jan. 2, 1949 struck, Jess Sparks, a farmer who lived northwest of Rapid City had twenty-one pigs. After the storm was over he could find but twenty of his pigs. He gave up, as lost, the missing pig. Forty-four days after the snow storm had buried the pig, Mr. Sparks heard a grunt. Digging through several feet of snow he soon released the pig, which walked out under its own power and, although very thin, did not resume eating at once.
A similar incident was reported by Jack Stotts of Cody, Wyo., who dug out a straw-stack that had been buried twenty feet deep for sixty-three days and found two Hereford heifers a little wobbly but otherwise in good condition. John Lemke, a farmer, in Dupress, S. D., dug out a sow that had been buried for three months. At the time of her burial she weighed three hundred pounds. She was skinny when rescued, but able to walk three quarters of a mile to a feed trough.
On the Wm. Brandt farm near Fort Morgan, Colo., a sheep was found alive on Feb. 12, 1949, after having been entombed in a snowdrift for forty days, having been hemmed against a high board fence by the big blizzard that struck in early January. A companion sheep was dead. The two sheep had eaten away a small portion of a wooden fence. Other than this, they had no food while buried in the snow.
These are examples of burial of domestic animals. Wild animals must also frequently be buried by the snow and must remain for shorter or longer periods in their prisons. How many examples of burials similar to the foregoing burials of domestic animals that blizzard would have afforded, had they been recorded, we can only surmise. As the snow of the blizzard blanketed many thousands of square miles of territory, wild life could not have escaped it. Small animals especially were buried. They were forced to live without eating during their burial. The ability of an animal to fast for long periods under such conditions, means the difference between surviving and perishing.
Rabbits are well-known to be frequently buried in the snow. If we could know just how often such things occur in nature and how many hundreds of thousands of animals are thus forced to go without food for considerable periods each year, we would probably find that the ability to fast is a very important means of survival.
All animals adapt themselves in some manner to the winter season. Winter is a difficult period for many plants and animals in northern countries. With its short days, low temperature, stormy weather, scarcity of food both animals and plants are faced with the problem of keeping alive under very unfavorable circumstances. Both animals and plants have found many solutions to this problem, adapting themselves to winter in a wide variety of ways. Migration, as by birds, is but one of many solutions animals nave found tor this perplexing problem. Birds that migrate may lead a life as active in their southern homes as they do in their northern homes in the Spring and Summer. This is not so of animals that do not migrate.
Some animals store away supplies of food for this period. Bees store up honey, squirrels store away nuts, the mouse stores away food in various caches, the beaver stores twigs, gophers and chipmunks store up roots and nuts on which they feed when they awaken on an occasional warm day. On the colder days, these sleep and take no food. This is to say, many animals that store away food in various caches fast much during the winter months.
Other animals store their food supplies within themselves. These internal food supplies serve the animal as well as do the caches of food stored outside the body by other animals. We may say, then, that some animals store up their winter food supply within themselves. Hibernation by those animals that depend upon internal stores during the winter season is the solution for the exigencies of winter that has been adopted by more forms of life than any other solution. Bats, mice, hedgehogs, woodchucks, toads, newts, lizards, snakes, snails, flies, wasps, bees, and the great hosts of insects, bears, crocodiles, alligators, and many other animals do not migrate, but go into winter quarters. Animals that store up food outside themselves also carry internal supplies, for they, too, are often forced to go for extended periods without food. Squirrels, for example, frequently forget where they have buried their store of nuts.
Hibernation is a dormant state of existence, accompanied by greatly diminished respiration, circulation and metabolism, in which animals in the temperate regions spend the winter. During this period the animal functions are nearly suspended; the body heat is lowered to or nearly that of the air, the action of the heart is much reduced and the animal loses from thirty to forty percent of its weight. During hibernation the mammal may not feed, depending entirely on the stored food reserves within the body. The evidence at hand indicates that in such instances the body weight may drop as much as fifty per cent. Indeed, in bats, it drops more than this. In other animals food is stored within their winter nest and the hibernating animal awakens from time to time to consume its food.
Writing in The National Geographic Magazine (July 1946) under the title "Mystery Mammals of the Twilight," Donald R. Griffin says that hibernation of bats and other animals is still in many respects a mystery to biologists." Mystery or not, it is a common fact of nature and represents one of the means adopted by animals to adapt them to the exigencies of winter.
Hibernation is most common in cold-blooded animals that are unable to leave regions of severe winters, but it is also practiced by numerous warm-blooded animals. Some biologists say that the term hibernation should be restricted to a few mammals and prefer the phrase "lying low and saying nothing" for what they describe as the coma or lethargy of many of the lower animals, like some frogs and fishes, many snails and insects. Other biologists, although seeming to prefer to limit the term hibernation to the "winter sleep" of warmblooded animals, also include under this term, the "seasonal torpidity" of frogs, toads, reptiles, certain fishes, insects, the horseshoe crab and snails.
Among the many different forms of "lying low" seen in the winter life of animals are:
1. The relapsed life of some insect pupae, where the body of the larva (i.e., maggot) has become greatly simplified in structure; in fact almost embryonic again.
2. The arrested development of other insect larvae, such as caterpillars and pupae, where the metamorphosis into the winged form has ceased for the time being, like a stopped watch.
3. The suspended animation of small creatures, like bear animalcules (some of them quaintly like microscopic hippopotami) and wheel animalcules and small thread worms, in which we can detect no vitality for the time being.
4. The comatose state of snails and frogs, where we can see the heart beating, though the life of the body as a whole is at a very low ebb.
5. The state of true hibernation, restricted to a few mammals, such as hedgehog and dormouse, marmot and bat. This is a peculiar state very unlike normal sleep, with most of their vital functions, even excretion, in abeyance, with the heart beating very feebly and the breathing movements scarcely perceptible.
In all of these forms of 'lying low" the animals hide away and cease their activities and approach a state of suspended animation during the winter months. Hibernation, so common among animals appears, then, to be one aspect of the general tendency of animals to withdraw from an unfavorable environment. In hibernation the animal passes through the unfavorable period of low temperature and food scarcity in a dormant state. Thus hibernation, like migration, is one of the means of solving the food problem during the period of acute scarcity.
Mammals that hibernate are referred to by certain biologists as "imperfectly warm-blooded types," which are unable to produce enough animal heat to make good their losses in cold weather. It is doubtful if this is true of those species in which only the female hibernates. Food scarcity, rather than depressed temperature, seems to be the chief reason for hibernation. As estivation is practically identical with hibernation, only taking place under certain opposite conditions (when it is hot rather than cold) but where, as in hibernation, there is food scarcity, those mammals that estivate cannot be said to be "imperfectly warm-blooded types." The example of the tenree, that estivates at the time for estivation, even when far removed from its Madagascar home and placed where the temperature is warm and there is an abundance of food, would seem to indicate that there is more to this phenomenon than merely the external circumstances under which it occurs.
Hibernation resembles sleep and has been likened to a trance, but it is not sleep. The hibernating animal does sleep all or most of the time it hibernates, but hibernation is different from sleep. Sleep is not seasonal and is not occasioned by scarcity of food. Hibernation is prolonged and body temperature drops very low in this state whereas it tends to remain normal in sleep. Heart beat and respiration are very low in hibernation, they are reduced but slightly in sleep. Excretion is suspended in hibernation, it may be increased in sleep. There is great loss of weight during hibernation, in sleep there may be a gain of tissue. Hibernation is confined to the cold season, sleep takes place throughout the year, both at night and in the day time and lasts but a tew minutes to a few hours at a time. Griffin says that the "torpor of hibernation is much more prolonged than ordinary sleep."
Is it correct to refer to hibernation as a comatose condition? Is the animal in a coma? Is the hibernation state one of torpor, lethargy, stupor? These terms are frequently used by biologists in describing the hibernating condition. Coma is defined as an "abnormal deep stupor occurring in illness or as a result of it," such as alcoholic coma, apoplectic coma, uremic coma, diabetic coma, coma vigil, etc. It would be interesting to know what a normal coma is. Stupor is defined as a "condition of unconsciousness, torpor, stupor. A state analogous to hypnotism, or the first stage of hypnotism." It is seen in African sleeping sickness, encyphalitis lethargica, hysteria and other pathological states. Torpor is "numbness, abnormal inactivity, dormancy, apathy." Torpid means "not acting vigorously, sluggish." Biologists use such terms as coma, comatose, lethargic, stupor, trance, etc., in describing hibernation as though there is something essentially pathological about it.
Dormant is perhaps the better word, as the root dor means sleep, although, as previously pointed out, hibernation is not synonymous with sleep. Dormant means "being in a state resembling sleep, inactive, unused." That hibernation does resemble sleep in many particulars is certain; that the hibernating animal is even more inactive than in sleep is equally true. Perhaps we can define hibernation as a dormant state of existence accompanied with greatly diminished respiration, circulation and metabolism in which many animals in the temperate regions pass the winter.
In hibernation the animal seeks out a secluded nook or burrow or a cave, where the temperature is higher than that outside and sinks into a strange reptile-like state. There it lies, or as in the case of the bat, hangs, in safety through the cold and storm. It eats nothing, it excretes nothing, the heart beats feebly, the breathing movements are scarcely perceptible--yet it survives. Indeed, it seems certain that it would not survive otherwise. Thus, hibernation viewed biologically, is seen to be an adaptation to the cold of winter by which the animal is enabled to survive.
Danger lies in sub-freezing weather for the hibernating mammal and many are frozen to death where their place of abode becomes too cold. Griffin says of the bat: "Another important requirement also usually satisfied by caves and burrows is that the temperature should not go below freezing. Apparently no mammal can survive freezing when it is hibernating and its body temperature is at the mercy of the surrounding air temperature." He tells of finding bats in caves, the openings of which are great enough to permit freezing, frozen up in huge ice stalactites. Most of the bats, he says, awaken and fly away to another and better sheltered cave, when the cave in which they are hibernating begins to get cold.
Perhaps before we give our attention to hibernation among animals we may profitably take a hasty glance at the hibernating practices of plants. The "winter sleep" of trees, shrubs and many other plants is seen on every hand during winter. With the approach of Fall, these shed their leaves, their sap descends and they exist in a dormant state until the coming of Spring. In like manner bulbs, tubers, etc., undergo a prolonged "winter sleep." These plants fast through the whole of the winter months, taking no food during the time. They take no carbon and nitrogen from the air and extract no minerals and nitrates from the soil. Metabolism is practically non-existent during this period. The cessation of the flow of sap in trees during the winter season is similar to the almost ceasing of circulation in hibernating animals. Plants like the daffodil, onion, beet, turnip, etc., store up large supplies of food in their roots--bulbs and tubers--during the Summer. Their tops die off in the late Fall or early Winter and they lie dormant during the long Winter, only to send up new stems and leaves when Spring arrives. This storing up of food in their roots is similar to the storing of fat by the bear.
Hibernation is common among insects and is seen in every group of vertebrates except birds, which substitute migration for hibernation. It is largely found in insect and vegetable eating species. Hibernation occurs regularly throughout the winter in such invertebrates as snails, crustaceans, myriapods, insects, arachnids, and the lower vertebrates, such as reptiles, amphibians and some fresh-water fishes. Many mammals inhabiting the colder regions, especially species living on the ground, or whose principle sources of food are unavailable in the winter, are known to hibernate. In such hibernating animals as the bat, ground-squirrel, marmot, hedgehog, or dormouse, the temperature of the body drops from its typical warm condition to one or two degrees Centigrade above that of the surrounding air. In maximum dormancy the heart-rate is slowed considerably, sometimes to only one or two percent of the normal heart rate, the respiratory movements drop off to a similar extent and determination of oxygen consumption indicates a reduction to as low as three to five per cent of normal consumption.
During hibernation the animal may not feed, depending entirely upon the stored food reserves within his body. The evidence at hand indicates that in such cases the body weight may drop as much as fifty per cent. In other cases food is stored within the winter nest and the hibernating animal awakens from time to time to consume its food. In winter there are periods of fasting in those animals that hibernate only in a limited sense. Mice and squirrels, for example, that store food for the winter, often sleep for days at a time, without eating.
The bear is a typical hibernator, although not all bears hibernate. For example, the American grizzly bear does not. In the Himalayan or Asiatic black bear, hibernation is not complete as the bear comes out on warm winter days to feed. The brown bear, on the other hand, hibernates. In several species of bear only the female dens up in winter and appears to undergo a partial hibernation during which the young are born, the young cubs and the emaciated mother emerging in the Spring. The Polar bear is an example of this kind. The black bear, native to North America, gives birth to two or three cubs while hibernating. At birth these cubs are naked and blind, and are but eight inches long. Hibernating bears are believed not to attain full dormancy.
The big black bear of northern Russia retires to a bed of leaves and moss about the end of November and "sleeps," if not disturbed, until about the middle of March; living during this time, upon the nutritive supplies stored in his own tissues. The fat, or well-fed bear will begin to fast some weeks before he retires to his den for his long winter's "sleep." Disturb him in the latter part of February and he will be instantly awake and alert, and will attack the intruder with a fury which has given rise to the expression, "as savage as a waked winter bear."
Nearly all the burrowing rodents hibernate. Notable exceptions are gophers, chipmunks and squirrels which store up roots and nuts on which they feed when an occasional warm day induces them to arouse. On the colder days even these hibernate. The prairie dog and squirrel are said to be partial hibernators. In the northern part of his range the badger hibernates during the winter. He passes through a long winter without eating. After an absolute fast of ten weeks he will trot for miles in search of acorns or roots which he may then be forced to dig out of the half-frozen ground.
The dormouse (sleeping mouse) a term applied in the old world to a small squirrel-like rodent and in the U.S. to the common white-footed mouse is a long "sleeper" but seems not to "sleep" as deeply nor to be as far from consciousness as some other hibernating mammals. He makes himself very comfortable by weaving a thick network of dry grass into his winter bedclothes. This is so neatly and skillfully designed that it keeps in the heat and, yet permits a fair amount of air slowly to filter through. So carefully does he fill up the hole in his warm light wrapping, after he goes inside, there is no hint of a joint or a weak place. Here he spends a long winter of five months in deep "sleep" with no food and often loses more than forty per cent of his weight during this period.
The hibernating habits of different species of bats differ so much that it is difficult to generalize. There is some evidence that some bats migrate upon the approach of winter, but most of them hibernate. Bats live on winged insects and must catch their prey in the air. Their feeding days are limited, except in the South, where insects fly about for a longer season. Indeed, their feeding days must be very short if frost comes early in Autumn. Their period of hibernation may be more than half a year. Their death-like inactivity is made necessary because of the need to make their meagre supply of stored food hold out over such a long period of time. In the long winters of the north, hibernation often means going without food for five, six and seven months. If bats are to survive, it is essential that their food resources be made to hold out as long as possible.
Bats cluster in masses, usually in caves, old barns, and other places that offer protection from the inclemencies of winter. The hibernating bat appears in all respects dead. Its temperature sinks very low, its heart beats so feebly it is barely perceptible, and it takes long to awaken from its sleep. One naturalist describes the "winter sleep" of bats in the following words: "Most bats when fallen into their winter sleep look dead as nearly as may be. They grow cold, their heart beats feebly, and when they hang themselves head downward on some dusty beam or crouch in some smouldering wood, they might be taken for lumps of leather. Nothing about them suggests a living creature, and no one would imagine for a moment that they would presently be flying with a dash and a skill and a command of quick turns beyond the power of a bird."
Griffin says of the hibernating bat, "the heart rate slows to a point where it cannot be detected. Breathing almost ceases. The blood moves sluggishly. The body temperature falls almost to that of the surroundings.
"Bats hibernating in a cave where the air temperature is 33° F. may have a body temperature of 33.5° F. They feel cold to handle, and are stiff and unresponsive. It requires close observation to distinguish a hibernating bat from a dead one."
There is evidence that bats may awaken spontaneously during the winter and fly around in their cave, even in rare instances, flying considerable distances to other caves. Griffin says that "they are not continuously dormant throughout the whole winter. On successive visits to the same cave we usually found the bats in different parts of the passages, even when they were not disturbed on the previous visit. Probably they wake up from time to time and fly about a bit, perhaps occasionally wandering out of the cave to see whether spring has come yet, and then hang themselves up again for another long sleep." "Flying from cave to cave in winter seems to be a rare occurrence, but we obtained three returns of banded bats which had flown 55 to 125 miles from one cave to another during a single winter."
While hibernating mammals seek caves, dens or hollow logs, usually making themselves dens of dry leaves or grass to sleep through the winter, the lower orders remain buried throughout the winter with the body temperature approximately that of the external environment, and with great decrease in metabolism. Reptiles hide away among stones or pits or caves, often coiling together, to form a huge, inert mass. Frogs, lizards, salamanders and certain fishes bury themselves in the earth below the reach of frost, the aquatic (forms digging into the mud at the bottom of the stream. The few fishes which are known to lie dormant and take no food, sink into the mud of the streams or of the sea. Some fish, as the carp, lie quiet on mud bottoms. The horseshoe crab buries into the mud beyond the reach of oyster dredges in November, remaining in deep water until the middle of Spring. Because snakes hibernate so deep below the ground that frost never reaches them, they live further north than any other reptile. Spiders and snails hibernate under stones, moss, etc., while slugs bury themselves in the mud and muscles and other molluscs living in the streams and lakes, descend into the mud.
As cold weather comes and winter approaches the purely aquatic species of frogs take to the water and burrow into the moist mud at the bottom of the ponds below the frost line. Here they hibernate throughout the winter, becoming cold and dormant, where the climate is severe, until revived in the Spring. Others bore into the soil, or beneath the fallen leaves, or into the rotting stumps, etc., and exist quietly and dormant until the coming of warm weather and food. During this period, most of the life activities of the frog cease. The heart beats very slowly and there is little evidence of life. The frog does not breathe through its lungs during this period but takes in oxygen through its skin. Toads also hibernate through winter. Hibernating frogs and toads take no food, being dependent during this time on the food reserves stored in their bodies as fat and glycogen. All activities are suspended except those necessary to maintain life, such as the beating of the heart. Metabolism is much reduced, little oxygen is required, and respiration takes place entirely through the skin. Many other amphibians bury themselves in mud, this being particularly true of those that estivate during the dry season.
Lizards residing in the temperate zones hibernate during the winter. Here in the Southwest, the great variety of lizards, some brilliantly colored, others dull and drab, like the noted horned toad, that one sees in the Summer months, is almost bewildering. Upon the approach of Winter they disappear. They may be found under boards, piles of straw, logs, etc., dormant and almost incapable of activity. If placed near a fire and made warm, they become as active as in the Summer months.
Newts are more difficult to find than lizards, but if one digs into the hole, often far down into the ground, where a newt is spending the winter, one may find a black shriveled object that is scarcely recognizable.
The snail prepares a really tough defense for itself. It seeks a hiding place, preferring a damp and rather warm atmosphere, and when ensconced in its new home, manufactures from its own juices a chalky secretion covering the mouth of its cell. By puffing from its lungs it separates this covering from contact with itself. This defensive covering is porous to the air so that the sleeping snail can breathe. It then shrinks into the deep recesses of its shell instead of filling out the whole of it. Here it spends the winter in sleep, taking no food during the whole of this period.
Most insects hibernate in the larval or pupal stage. The larvae of many caterpillars hatch in Summer and sleep all Winter. A few insects, as certain moths, butterflies and beetles, hibernate in the adult stage. Caterpillars hide under moss, the bark of trees, etc., but they freeze solid and may be broken into pieces like an icicle; they gradually thaw out in the Spring, but when the changes are sudden, great numbers die. In Europe insects pass the winter, not as adults, but in the pupa stage, well wrapped up in a cocoon.
The queen bumble bee makes for herself a hole in the ground, the sides of which she polishes very thoroughly. She goes into this winter home in early October and does not come out for five months or more. She shifts her position and has moments of restlessness but does not take food. She sleeps through all or most of her period of hibernation.
Queen wasps, though preferring a hole behind a piece of loose bark or in the wood of a decaying tree, employ a greater variety of hiding places than does the bumble bee, and retire in September. They are wide awake and active if the weather becomes warm.
In general the time of the initiation of hibernation corresponds closely with the scarcity of food and lowering of temperature. The termination coincides with the return of favorable conditions. Some species, or some individuals, however, may commence the hibernating period while factors are still quite favorable, or may terminate the period at an unfavorable time. Modern theories of the mechanism stress the physiological sequence of events characteristic of the process. These events may apparently be set into activity under any one of several external conditions.
In temperate climates bears eat more, especially of flesh in the Fall, as they are laying up a store of food in preparation for their winter hibernation. They literally gorge themselves on foods which they convert into fat, but when they enter the dormancy period, stomach and intestines are empty.
Hibernating animals may be induced to awaken readily by "strong external conditions." Following awakening, there is gradual elevation of body temperature and a regaining of normal physiological activity and behaviour. Lowering the temperature of the body to approximately 0° C. (32° F.) has been reported to awaken hibernating mammmals, though some investigators report that animals may often be killed by freezing without awakening.
Just as there are some migratory birds that do not return home until May and leave again in August, so some hibernating animals do not come out of their dark quarters for as many as seven months. Their hibernating period is one of complete fasting. In general, the period of hibernation corresponds with the period of cold and food scarcity.
In cold-blooded animals in a state of hibernation metabolism is almost at a complete standstill. Indeed, in some of them, as well as in frozen caterpillars, it must be at a complete standstill. Not so the metabolism of warm-blooded animals. These must maintain a minimum of physiological activity and keep up a certain amount of body heat, or freeze to death. At the same time, they must maintain metabolism at as low a level as is compatible with continued existence, else their food reserves may be exhausted before the end of winter, at which time they will also die of freezing.
The low rate of metabolism in the hibernating bat, manifest by slow respiration, slow heart action and sluggish circulation, means a very slow use of nutritive reserves. The same slow circulation, slow heart action and lessened rate of breathing seen in the hibernating bear also mean the same slow consumption of reserves. Exhaustion of reserves before the return of warm weather would result in death from starvation.
Griffin says that "in spite of the low level to which the metabolic processes have fallen, a hibernating bat will awaken in a few minutes if handled or even disturbed by lights and talking. Once awake, the bat is as lively and active as ever. His temperature, circulation, and respiration have returned to normal." Were this activity continued, exhaustion of food stores would rapidly result. He tells us that "after flying around for a few minutes they hang up again and relapse into the torpor of hibernation."
Mr. Griffin tells us that the metabolic rate of an animal in hibernation depends on the temperature of his surroundings: "he will burn more fat at a higher temperature, just as any chemical reaction is speeded up by a rise in temperature." This is not good physiology and I doubt the correctness of his statement. He, himself, shows that the hibernating bat may be awakened and become active, his temperature, circulation and respiration becoming normal in spite of the low temperature of his surroundings. I think we must regard hibernation as a function of life that is vitally controlled and not absolutely determined by the temperature of the surrounding air. The control of metabolism is from within and not from without. There is a purposive conserving of food stores, not a mere passive non-use of these.
We witness, not a mere slowing down of "chemical reactions" by a lowering of temperature, but a reduction of physiological activities by a process somewhat analogous to sleep. By his own showing, these physiological activities are not helpless in the grip of temperature. They are speeded up or slowed down by the bat in the same temperature. Mr. Griffin may be a biologist, but he talks like a chemist. He thinks of the bat in terms of test-tubes, reagent bottles, retorts, etc., and not as a living organism that takes an active part in the control of its behavior.
The bat is not a cold-blooded animal and, even in hibernation, with metabolism reduced to the lowest point compatible with continued life, is able to maintain a body temperature slightly higher than that of its surroundings. It is able to increase or decrease its metabolism in the same temperature. It can be active or dormant in the same temperature. Hibernation seems to be an adjustment to certain environmental conditions--the absence of food supply seems to be more important in inducing this state than the reduction of temperature--rather than a passive yielding to outside influences. The reduction of metabolism is not the result of cold, but the result of the need to conserve food reserves. Oxydation in the animal body, while a chemical process, is a rigidly controlled process. The body does not start to burn and just continue to burn until it is consumed. The body's fat stores do not catch fire on hot days and go up in flames. Even in the hottest weather the fasting animal reduces its metabolic rate and conserves its food reserves. As a matter of fact, non-hibernating animals conserve their food reserves better in hot than in cold weather. This is due to the fact that more heat must be produced in cold weather to maintain normal body temperature. This "chemical reaction" is not speeded up by a rise in temperature; for, internally, there is no rise in temperature, though the surface of the body may feel chilly and the faster may complain of being cold even in hot weather.
It would be interesting to know what is the internal temperature of the bat in hibernation. It is, no doubt, much lower than in the active state. But the question remains to be answered: Is lowered, temperature due to reduced metabolism, or is lowered metabolism due to lowered temperature?
If the lowering of temperature comes from without and is responsible for the reduction of metabolism, it would seem to be impossible for the bat to arouse itself or be aroused from its state of "torpor" by anything short of an increase of temperature. So long as the temperature of the cave is thirty-three degrees, Fahrenheit, that of the bat should remain nearly as low and "torpor" should persist. It could not fly out of its cave to see if Spring has arrived, or more accurately, perhaps, to see if there is a food supply in evidence. If control is from without, the bat should be helpless until the control--temperature--is changed. Only the coming of warm weather should awaken him. Bats leaving a cave and flying to another when its temperature starts to drop to too low levels shows that the reduction of their metabolism is not a result of lowered temperature. For, if it were, a further lowering of temperature would further decrease metabolism and make it impossible for the bat to awaken and fly in search of a more sheltered abode.
The fact that some species commence their period of hibernation while the temperature is still relatively high and food is still to be had, indicates that the control of metabolism is from within, not from without. The hibernating animal is not helpless in the grip of external conditions.
Aestivation is similar to hibernation, if, indeed, it is not identical with it. If hibernation is to be called "winter sleep," aestivation may be with equal propriety, called "summer sleep." In zoology, it is defined as a state of reduced metabolic activity in which certain animals become quiescent. It is a resting interval associated with warm, dry periods in areas that have alternating wet and dry seasons. Animals are induced to aestivate when drought and heat interfere with their activities. With their bent for pathological interpretations, biologists also define aestivation as "the state of torpidity induced in animals by excessive dry heat." Physiological and physical quiescence should not be mistaken for a state of torpor. The same objections to calling it sleep that we made in the case of hibernation are also valid with reference to aestivation.
Aestivation is seen chiefly in the tropics during the long, hot, dry season, when food is scarce and vegetation is taking a rest. A few animals in the temperate zones, especially in the desert regions, also aestivate. Alligators, snakes, certain mammals, as taurec, insects and land snails become dormant.
During the dry season in the tropics the pools and streams dry up. The crocodiles aestivate in Summer, "sleeping" through the dry season without feeding or emerging from the mud in which they have buried themselves. It is said that they are able to "sleep" in this almost "lifeless" state for a whole year. The alligators, the American division of the crocodile family, hibernate in this country very much like frogs, but in the tropics they aestivate. When water is no longer obtainable the South American alligator, and some other animals, bury themselves in the mud, reduce their physiological activities to a bare minimum, while the earth above them is baked into a hard crust. When the rains come again, they resume activity, and come forward renewed by their long fast and rest.
Certain fish are able, when the pools and streams dry up, to burrow deep down into the mud and lie there until the coming of the rainy season. The mud-fish of Australia is an example of these fish, but many examples exist in the dry arid countries where summer, rather than winter, is the "hard time." Indeed, if we are to judge by the fish that may be found in a dry pond after a heavy rain, we may have such fish in this country. The lungfishes, Protoperis of Africa and Lipidosiren of South America, live in mud cocoons during the dry season. When the rice fields which it inhabits dry up during the drought, the spearhead fish, Opiocephidae, buries itself in the mud. Natives of Indo-Malaya "fish" for these animals with digging implements. The African lungfish digs into mud almost two feet, curls its tail around its body which becomes covered with mucus, and there exists, drawing air through a long tube and living on the breakdown of body fat and tail.
During droughts, planarians (flatworms) and leeches (annelids} bury themselves in mud. Small crustaceans, mollusks, etc., that are found in the pools and patches of water that frequently form in the desert, bury themselves deep in the clay or baked mud, when these pools dry up, and activate for long periods. Turtles activate in mud, while lizards and snakes retire to crevices. The Iberian water turtle hides under rocks.
Frogs burrow into mud and exist for months in its sunbaked hardness. During periods of aestivation frogs can survive the loss of half their body moisture. Certain Australian frogs become distended with water during the wet season and use this stored water during the aestivating period. This storing of water by these frogs is similar to the storage of fat by hibernating animals.
Birds are not known to activate, but a number of mammals, such as aardvark, Orycteropus, and some lemurs, Chirogale millii and Microcebus, undergo periods of quiescence.
Most prominent among aestivating animals of America are the land snails, although frogs, slugs, some fishes and other aquatic and semi-aquatic animals also aestivate. When the dry season comes, land snails secrete a membrane-like substance (epiphram), across the openings of their shells, leaving a small opening for the admission of air in breathing. Some snails secrete several diaphragms across the opening of their shells. There is an Australian snail that plugs the mouth of its shell with a morsel of clay before entering upon its period of aestivation. After a prolonged shower snails become active. Aestivating desert snails have been known to revive and crawl about after years in the dormant state. Records show that the African snail, Helix desertorum, may remain in aestivation as long as five years; the California desert snail, Helix veatchii, has become active after a six year aestivation period.
In the deserts of the world there are many plant-eating animals that lie dormant in times of drought, when vegetation is more scarce than during those periods when there is rainfall. There are many desert plants that also lie dormant during periods of drought. Both plants and animals fast during this period of dormancy.
In Australia the nymphs of a species of dragonflies aestivate in dry land. Slugs bury themselves in the ground and bivalve mollusks in the mud. Small crustaceans, mollusks, etc., that are found in the pools and patches of water that frequently form in the deserts, bury themselves deeply in the clay or baked mud, when these pools dry up and estivate for long periods.
While it seems that heat, dryness, and lack of food are the factors that induce aestivation, as cold and famine seem to induce hibernation, there is reason to believe that there is more to the practice than the mere existence of certain external factors. For example, the persistence of the aestivating habit is illustrated by the tenree, which in temperate zoological gardens, where food and water are abundant, aestivates at the time of their scarcity in its native Madagascar. This would seem to indicate that something other than scarcity of food and temperature is at work in aestivation, and, perhaps, also in hibernation.
A peculiar example of an animal that behaves opposite to aestivation is the Egyptian jerboa. It is said to be so closely adapted to dry conditions (of the desert) that rain or damp atmosphere induce it to pass into a dormant condition, in which state it does not eat.
The most remarkable records of continued abstinence from food are to be found among the lower animals. Compared to some of these, man is a piker. It is often said that the marvels of long-continued abstinence from food reach their maximum in the "winter sleep" of several species of warm-blooded animals, but there are actually longer records than these present.
The recently produced American People's Encyclopedia tells us that the survival time in acute starvation (complete abstinence from all food save water) ranges from 21 to 117 days in dogs; rat 5 to 6 days; guinea pig 7 to 8 days; rabbit 15 days; cat 20 days; dog 38 days. There is some confusion about how long the dog may survive deprivation of food, although the matter of size may determine.
Reports of spiders undergoing incredibly long fasts, spinning webs daily, these made of substances within their bodies, until the weight of the webs so produced far outweigh the weights of the spiders at the beginning of the fast, cause me to suspect that the spiders had sources of food supply of which the observers were unaware. I find it difficult to believe that spiders have mastered the art of making something out of nothing.
Even one-celled organisms (amoeba, paramecia, etc.) can exist without food for from four to twenty-one days. Like muscle cells in a fasting man, fasting one-celled organisms only undergo a diminution in the size of the cell. These die only after the cellular reserve is exhausted. These little beings possess a food reserve which they can live on in emergencies. In the same way, each cell in the bodies of the higher animals possesses its own private food reserve.
Among vertebrates the time they can subsist without food ranges from a few days in small birds and mammals to possibly years in some reptiles. The time they can go without food depends on the amount of reserve possessed and the rate at which it is consumed. In coldblooded animals, the reserves are usually plentiful and the demand made upon them is small, so that they may fast for long intervals, without being forced to renew their stores. In warm-blooded animals, whose reserves are frequently lower and whose great activities make a greater demand upon these, the reserves are more rapidly depleted.
Among cold-blooded animals the survival time without food is usually much greater than among warm-blooded animals, since the former do not have to "burn fuel" in order to maintain a high body temperature. Snakes and other reptiles easily go for long periods without food. Snakes have been kept alive without food for almost two years. A python in captivity has been observed to go without food for a period of thirteen months. Frogs have survived sixteen months and fishes twenty months without food. Invertebrates can stand even longer periods of deprivation; the larva of the beetle Trogderma tarsale living for five years, during which time they lost 99.8 percent of their body substance. Spiders have been observed to exist without food for seventeen months and more. Fabre tells us of certain spiders that they eat no food of any kind for the first sixteen months of their lives but feast upon sunbeams. Gold fishes have been known to go for long periods without food, while proteus angeainus, an amphibian, has been known to live for years without food. In his Researches sur L'lnanition, Chossat tells us that the land tortoise of southern France, can "starve" for a year without betraying a reduction of vital energy, and that Proteus anguinus, the serpent salamander, even for a year and a half, providing the temperature of its cage is kept above the freezing point. Rhine salmon have been known to go without food for eight to fifteen months.
Oswald says: "Reptiles, with their small expenditure of vital energy, can easily survive dietetic deprivations; but bears and badgers, with an organization essentially analogous to that of the human species, and with a circulation of blood active enough to maintain the temperature of their bodies more than a hundred degrees above that of the winter storms, dispense with food for periods varying from three to five months, and at the termination of their ordeal emerge from their dens in the full possession of their physical and mental energies."--Fasting Hydropathy and Exercise, pp. 60-61. The condor, like all other vultures, is able to fast for days. It usually gorges itself, however, when it does get food.
Edwin E. Slossom, M.S., Ph. D., Director of Science Service, Washington, says in his Keeping Up With Science (Page 261): "Among the lower animals existence under inanition may extend over incredibly protracted periods. Scorpions are known to have starved for 368 days, and spiders have survived starvation for seventeen months. The larvae of small beetles have been known to live through more than five years without food, their body mass being reduced in this time to only one-sixth-hundred of what it was at the start. There is a unique record of a fresh water fish, Amia Calva, which fasted twenty months and even then had not apparently reached the end of the rope but was killed. Frogs survive starvation for sixteen months, and snakes remain alive even after two years of fasting. The longest recorded fast endured by a dog was 117 days, or nearly four months."
A. S. Pearse, Professor of Zoology at Duke University, tells us that "certain ticks can exist in an active state for as long as four years without eating anything."
Perhaps the longest periods of abstinence are seen in aestivating animals of the deserts. It should not be overlooked, also, that snails and other animals of northern deserts, that activate in the dry season and hibernate through the winter, spend most of their lives fasting.
After this survey of the many and varied conditions under which animals fast, and the different uses to which fasting is put, it becomes obvious that fasting is one of the most common phenomena in nature. It is second only to feeding and reproduction, with both of which phenomena it is allied, in importance and in breadth of application.
Fasting under so many different conditions is so common in nature and is employed as a means of meeting so many of the exigencies of life that I am forced to wonder why anyone is afraid to fast and why anyone should doubt its naturalness and helpfulness. It is one of nature's best established methods of dealing with certain physiological problems. The hibernating bear, the aestivating alligator, the sick elephant, the wounded dog--these all fast to meet the problems before them. Fasting in acute disease, when there is no digestive power, can be viewed only as a very useful means of adaptation.
As I have previously pointed out, biologically, hibernation is a means of adaptation to the conditions of winter which enables the animal to survive. The ability to go without food during this period is an important element in survival. Except for its ability to fast for extended periods, the hibernating animal would starve to death during the winter.
Our so-called scientists, sticklers as they are for classifications and minute differentiations, are still in the habit of referring to all abstinence from food as starvation. But they say of hibernation that it is a form of "starvation" that "spells survival instead of death." Strangely enough, these men refer to the abstinence of hibernation and that seen in the mating season in some animals as "physiological starvation." This is a misuse of terms. Starvation is at all times pathological, or, pathogenic.
The ability of an animal to fast, even for long periods, under many and varied conditions and circumstances of life, is a vitally important factor in survival. It is nature's best established method of dealing with certain physiological and biological problems. It may be properly regarded as a means of adjustment or adaptation--the hibernating bear, the activating alligator, the sick elephant all fasting to meet the problems before them.
If an animal can fast, it is only because it can rely upon adequate internal resources and it can afford to fast precisely in so far and so long as it duly conserves these provisions. This is the reason hibernating and activating animals function on the lowest physiological level compatible with continued life. With no physical activity and only a bare minimum of physiological activity, their internal reserves are conserved and made to last for prolonged periods--months or a year.
Salmon and the fur-seal bull do not rest and they make no effort to conserve their resources. It would be interesting to know how long these animals could fast if they ceased their activity--physical and sexual.
Fasting during the mating season probably serves some very useful purpose. We know at least, that in the case of certain very low forms of life, it restores the male after several generations of parthenogenetic reproduction. For best results, animals that fast during the mating season seem to require a reduction of surfeit. They purchase rejuvenescence by curbing their anti-symbiotic propensities and abandoning conditions of surfeit. Instability resulting from surfeit and illegitimate food can be gotten rid of and stability regained only by a return to moderation and appropriate food. For immediate results abstinence from food is essential.
Reinheimer thinks that fasting has the effect of assisting towards a re-establishment of a tolerable degree of domestic symbiosis--both for ordinary physiological, as well as for genetic purposes--in those cases where domestic symbiosis is in danger of becoming perverted by the particular organism's transgressions against the laws of biological symbiosis.
I have made no effort to exhaust the list of animals and plants that fast under conditions other than those of sickness or absence of food. The examples that have been given are sufficient to show that nature has no fear of prolonged abstinence from food and that abstinence is frequently made use of in nature, by animals in both the active and the dormant states, as a means of adapting the animal to various conditions of life, or as a means of internal alteration when this is needed. Under all conditions in which animals fast, the internal resources of the animal are drawn upon to nourish the vital tissues and carry on the indispensable functions of life.
In sickness, or when severely wounded, when no food can be digested, the organism also draws upon its internal store of supplies for these same purposes. Fever, pain, distress, inflammation suspend the secretion of the digestive juices, inhibit the muscular actions of the stomach and take away the desire for food. In such conditions there is but one source from which food can be drawn--the reserves.
In sickness, as in animals fasting through the mating period, there is much activity going on in the body. There is, therefore, much more rapid wasting of the body in these two conditions than is seen in hibernation and aestivation.
Viewing the wasted condition of animals at the end of their various fasting periods, it becomes very obvious that, while different species of animals vary in the amount of loss they can safely sustain, none of them are injured or endangered until after a large percentage of the normal weight of the body has been lost. There is, therefore, no danger in a fast of such lengths as are employed in sickness.