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78-473: It is one of the oldest Ute ceremonies. The Bear Dance was first recorded by Spanish conquistadors in the 15th century, but oral tradition dates it to be a thousand years old or older. and continues to be performed by modern Ute. The bear symbolizes leadership, strength, and wisdom. Traditionally, a group of men play musical rasps for the dance. According to Ute tradition, the Bear Dance was first taught to

156-596: A hemisphere is oriented away from the Sun . Different cultures define different dates as the start of winter, and some use a definition based on weather. When it is winter in the Northern Hemisphere , it is summer in the Southern Hemisphere , and vice versa. Winter typically brings precipitation that, depending on a region's climate , is mainly rain or snow . The moment of winter solstice

234-408: A common proto-hibernating ancestor of birds and mammals, the ability to hibernate or go through torpor would have been lost in most larger mammals and birds. Hibernation would be less favored in larger animals because as animals increase in size, the surface area to volume ratio decreases, and it takes less energy to keep a high internal body temperature, and thus hibernation becomes unnecessary. There

312-413: A continuum and utilise similar mechanisms. The equivalent during the summer months is aestivation . Hibernation functions to conserve energy when sufficient food is not available. To achieve this energy saving, an endothermic animal decreases its metabolic rate and thereby its body temperature. Hibernation may last days, weeks, or months—depending on the species, ambient temperature, time of year, and

390-406: A later point. This difference in development is evidence, though inconclusive, that they evolved by slightly different mechanisms and thus at different times. As reptiles are ectothermic, having no system to deal with cold temperatures would be deadly in many environments. Reptilian winter dormancy, or brumation, likely evolved to help reptiles survive colder conditions. Reptiles that are dormant in

468-482: A low of −21.4 °C (−6.5 °F). In comparison, Vancouver , on the west coast (with a marine influence from moderating Pacific winds), has a January low of 1.4 °C (34.5 °F), with days well above freezing, at 6.9 °C (44.4 °F). Both places are at 49°N latitude and in the same western half of the continent. A similar but less extreme effect is found in Europe: in spite of their northerly latitude,

546-505: A means to survive in their shoreline habitat, where water and oxygen levels vary with the tide. Other animals able to survive long periods with very little or no oxygen include goldfish , red-eared sliders , wood frogs , and bar-headed geese . The ability to survive hypoxic or anoxic conditions is not closely related to endotherm hibernation. Some animals can literally survive winter by freezing. For example, some fish , amphibians , and reptiles can naturally freeze and then "wake" up in

624-529: A modest decline in body temperature (3–5 °C) compared with the much larger decreases (often 32 °C or more) seen in other hibernators. Many researchers thought that their deep sleep was not comparable with true, deep hibernation, but this theory was refuted by research in 2011 on captive black bears and again in 2016 in a study on brown bears . Hibernating bears are able to recycle their proteins and urine, allowing them to stop urinating for months and to avoid muscle atrophy . They stay hydrated with

702-533: A periodic internal clock, which is likely triggered by cooler outside temperatures, as shown in the Texas horned lizard ( Phrynosoma cornutum ). One mechanism that reptiles use to survive hibernation, hypercapnic acidosis (the buildup of carbon dioxide in the blood), is also present in mammal hibernation. This is likely an example of convergent evolution . Hypercapnic acidosis evolved as a mechanism to slow metabolism and also interfere with oxygen transport so that oxygen

780-418: A physiological state wherein the body temperature drops to near ambient temperature, and heart and respiration rates slow drastically. The typical winter season for obligate hibernators is characterized by periods of torpor interrupted by periodic, euthermic arousals, during which body temperatures and heart rates are restored to more typical levels. The cause and purpose of these arousals are still not clear;

858-415: A response to stressors from the environment. A good example of the differences between these two types of hibernation can be seen in prairie dogs . The white-tailed prairie dog is an obligate hibernator, while the closely related black-tailed prairie dog is a facultative hibernator. While hibernation has long been studied in rodents (namely ground squirrels ), no primate or tropical mammal

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936-442: A seasonal diapause, where many of their biological functions end up paired with a seasonal rhythm within the organism. This is a very similar mechanism to the evolution of insect migration, where instead of bodily functions like metabolism getting paired with seasonal indicators, movement patterns would be paired with seasonal indicators. While most animals that go through winter dormancy lower their metabolic rates, some fish, such as

1014-459: A week to ten days, beginning after the first thunder of the spring, which usually occurs in March. Ute people of all ages are involved in this yearly dance, although some traditions say women who are menstruating or pregnant should not attend. Both men and women prepared for the bear dance. Traditionally, women prepare the clothes to be worn during the dance, while the corral and other things related to

1092-434: A winter with a particular year, e.g. "Winter 2018". Solutions for this problem include naming both years, e.g. "Winter 18/19", or settling on the year the season starts in or on the year most of its days belong to, which is the later year for most definitions. Ecological reckoning of winter differs from calendar-based by avoiding the use of fixed dates. It is one of six seasons recognized by most ecologists who customarily use

1170-507: A young hunter by a she-bear. The primal ancestor of the Ute Indians are believed by themselves to be bears. The dance celebrates both the waking of hibernating bears and in winter, and the time when, historically, Ute people were able to break winter camps and look for food and game. Along with waking up for winter finding a new mate for the new season is another reason this dance is performed by bears, and humans. The Bear Dance lasts

1248-550: Is 1 or 2 February. In Chinese astronomy and other East Asian calendars , winter is taken to commence on or around 7 November, on Lìdōng , and end with the arrival of spring on 3 or 4 February, on Lìchūn . Late Roman Republic scholar Marcus Terentius Varro defined winter as lasting from the fourth day before the Ides of November (10 November) to the eighth day before the Ides of Februarius (6 February). This system of seasons

1326-490: Is based on the length of days exclusively. The three-month period of the shortest days and weakest solar radiation occurs during November, December and January in the Northern Hemisphere and May, June and July in the Southern Hemisphere . Many mainland European countries tended to recognize Martinmas or St. Martin's Day (11 November) as the first calendar day of winter. The day falls at the midpoint between

1404-462: Is driven by environmental cues, but arousal is driven by physiological cues. Ancient people believed that swallows hibernated, and ornithologist Gilbert White documented anecdotal evidence in his 1789 book The Natural History of Selborne that indicated the belief was still current in his time. It is now understood that the vast majority of bird species typically do not hibernate, instead utilizing shorter periods of torpor . One known exception

1482-533: Is earlier than the solstice delimited definition, but later than the daylight (Celtic or Chinese) definition. Depending on seasonal lag , this period will vary between climatic regions. Since by almost all definitions valid for the Northern Hemisphere, winter spans 31 December and 1 January, the season is split across years, just like summer in the Southern Hemisphere. Each calendar year includes parts of two winters. This causes ambiguity in associating

1560-402: Is evidence that hibernation evolved separately in marsupials and placental mammals, though it is not settled. That evidence stems from development, where as soon as young marsupials from hibernating species are able to regulate their own heat, they have the capability to hibernate. In contrast, placental mammals that hibernate first develop homeothermy , only developing the ability to hibernate at

1638-409: Is most commonly used to pass through winter months – called overwintering . Although traditionally reserved for "deep" hibernators such as rodents , the term has been redefined to include animals such as bears and is now applied based on active metabolic suppression rather than any absolute decline in body temperature. Many experts believe that the processes of daily torpor and hibernation form

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1716-571: Is nearly always a male singer, who banters with the audiences in between songs, speaking both on traditional beliefs and modern life, often humorously. Some Christian Ute have interpreted the dance as being given to the Ute people by Jesus Christ. Hibernation Hibernation is a state of minimal activity and metabolic depression undergone by some animal species. Hibernation is a seasonal heterothermy characterized by low body-temperature, slow breathing and heart-rate, and low metabolic rate . It

1794-433: Is not used up and can still reach tissues in low oxygen periods of dormancy. Seasonal diapause, or arthropod winter dormancy, seems to be plastic and quickly evolving, with large genetic variation and strong effects of natural selection present as well as having evolved many times across many clades of arthropods. As such, there is very little phylogenetic conservation in the genetic mechanism for diapause. Particularly

1872-439: Is referred to as diapause. Some researchers and members of the public use the term brumate to describe winter dormancy of reptiles, but the more general term hibernation is believed adequate to refer to any winter dormancy. Many insects, such as the wasp Polistes exclamans and the beetle Bolitotherus , exhibit periods of dormancy which have often been referred to as hibernation, despite their ectothermy. Botanists may use

1950-466: Is referred to as the eve of the birth of Mithra , who symbolised light, goodness and strength on Earth. In Greek mythology , Hades kidnapped Persephone to be his wife. Zeus ordered Hades to return her to Demeter , the goddess of the Earth and her mother. Hades tricked Persephone into eating the food of the dead, so Zeus decreed that she spend six months with Demeter and six months with Hades. During

2028-492: Is the common poorwill ( Phalaenoptilus nuttallii ), for which hibernation was first documented by Edmund Jaeger . Because they cannot actively down-regulate their body temperature or metabolic rate, ectothermic animals (including fish, reptiles, and amphibians) cannot engage in obligate or facultative hibernation. They can experience decreased metabolic rates associated with colder environments or low oxygen availability ( hypoxia ) and exhibit dormancy (known as brumation). It

2106-425: Is thought to have originally evolved in three stages. The first is development of neuroendocrine control over bodily functions, the second is pairing of that to environmental changes—in this case metabolic rates decreasing in response to colder temperatures—and the third is the pairing of these controls with reliable seasonal indicators within the arthropod, like biological timers. From these steps, arthropods developed

2184-513: Is when the Sun's elevation with respect to the North or South Pole is at its most negative value; that is, the Sun is at its farthest below the horizon as measured from the pole. The day on which this occurs has the shortest day and the longest night, with day length increasing and night length decreasing as the season progresses after the solstice. The earliest sunset and latest sunrise dates outside

2262-519: The March equinox . These dates are somewhat later than those used to define the beginning and end of the meteorological winter — usually considered to span the entirety of December, January, and February in the Northern Hemisphere and June, July, and August in the Southern. Astronomically, the winter solstice — being the day of the year that has fewest hours of daylight — ought to be in the middle of

2340-479: The Proto-Indo-European root *wed- 'water' or a nasal infix variant *wend- . The tilt of the Earth's axis relative to its orbital plane plays a large role in the formation of weather. The Earth is tilted at an angle of 23.44° to the plane of its orbit, causing different latitudes to directly face the Sun as the Earth moves through its orbit. This variation brings about seasons. When it is winter in

2418-611: The cunner , do not. Instead, they do not actively depress their base metabolic rate, but instead they simply reduce their activity level. Fish that undergo winter dormancy in oxygenated water survive via inactivity paired with the colder temperature, which decreases energy consumption, but not the base metabolic rate that their bodies consume. But for the Antarctic yellowbelly rockcod ( Notothenia coriiceps ) and for fish that undergo winter dormancy in hypoxic conditions, they do suppress their metabolism like other animals that are dormant in

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2496-412: The metabolic water that is produced in sufficient quantities to satisfy the water needs of the bear. They also do not eat or drink while hibernating, but live off their stored fat. Despite long-term inactivity and lack of food intake, hibernating bears are believed to maintain their bone mass and do not suffer from osteoporosis . They also increase the availability of certain essential amino acids in

2574-470: The British Isles lack non-mountain weather stations with a below-freezing mean January temperature. Meteorological reckoning is the method of measuring the winter season used by meteorologists based on "sensible weather patterns" for record keeping purposes, so the start of meteorological winter varies with latitude. Winter is often defined by meteorologists to be the three calendar months with

2652-551: The Earth's elliptical orbit) is negligible. The manifestation of the meteorological winter (freezing temperatures) in the northerly snow-prone latitudes is highly variable, depending on elevation, position versus marine winds, and the amount of precipitation. For instance, within Canada (a country of cold winters), Winnipeg , on the Great Plains (a long way from the ocean), has a January high of −11.3 °C (11.7 °F) and

2730-611: The Northern Hemisphere, due to the large land masses there. In the Southern Hemisphere, the more maritime climate and the relative lack of land south of 40°S make the winters milder; thus, snow and ice are less common in inhabited regions of the Southern Hemisphere. In this region, snow occurs every year in elevated regions such as the Andes, the Great Dividing Range in Australia, and the mountains of New Zealand, and also in

2808-424: The Northern Hemisphere, the Southern Hemisphere faces the Sun more directly and thus experiences warmer temperatures than the Northern Hemisphere. Conversely, winter in the Southern Hemisphere occurs when the Northern Hemisphere is tilted more toward the Sun. From the perspective of an observer on the Earth, the winter Sun has a lower maximum altitude in the sky than the summer Sun. During winter in either hemisphere,

2886-559: The QT interval changed for both typical hibernators and the bears from summer to winter. This 1977 study was one of the first evidences used to show that bears are hibernators. In a 2016 study, wildlife veterinarian and associate professor at Inland Norway University of Applied Sciences , Alina L. Evans, researched 14 brown bears over three winters. Their movement, heart rate , heart rate variability , body temperature, physical activity, ambient temperature, and snow depth were measured to identify

2964-561: The ancestor of birds and mammals onto land introduced them to seasonal pressures that would eventually become hibernation. This is true for all clades of animals that undergo winter dormancy; the more prominent the seasons are, the longer the dormant period tends to be on average. Hibernation of endothermic animals has likely evolved multiple times, at least once in mammals—though it is debated whether or not it evolved more than once in mammals—and at least once in birds. In both cases, hibernation likely evolved simultaneously with endothermy, with

3042-567: The animal to restore its available energy sources or to initiate an immune response. Hibernating Arctic ground squirrels may exhibit abdominal temperatures as low as −2.9 °C (26.8 °F), maintaining sub-zero abdominal temperatures for more than three weeks at a time, although the temperatures at the head and neck remain at 0 °C (32 °F) or above. Facultative hibernators enter hibernation only when either cold-stressed, food-deprived, or both, unlike obligate hibernators, who enter hibernation based on seasonal timing cues rather than as

3120-481: The animal to study key hibernation proteins (HP). Researchers have studied how to induce hibernation in humans. The ability to hibernate would be useful for a number of reasons, such as saving the lives of seriously ill or injured people by temporarily putting them in a state of hibernation until treatment can be given. For space travel, human hibernation is also under consideration, such as for missions to Mars . Anthropologists are also studying whether hibernation

3198-554: The bears' heart rate variability dropped dramatically, indirectly suggesting metabolic suppression is related to their hibernation. Two months before the end of hibernation, the bears' body temperature starts to rise, unrelated to heart rate variability but rather driven by the ambient temperature. The heart rate variability only increases around three weeks before arousal and the bears only leave their den once outside temperatures are at their lower critical temperature. These findings suggest that bears are thermoconforming and bear hibernation

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3276-406: The body's ability to maintain both core and surface heat of the body. Slipping on icy surfaces is a common cause of winter injuries. Other injuries from the cold include: Rates of influenza , COVID-19 , and other respiratory diseases also increase during the winter. In Persian culture , the winter solstice is called Yaldā (meaning: birth) and has been celebrated for thousands of years. It

3354-651: The daily mean temperatures are below 0 °C (32 °F) for five consecutive days. According to the SMHI, winter in Scandinavia is more pronounced when Atlantic low-pressure systems take more southerly and northerly routes, leaving the path open for high-pressure systems to come in and cold temperatures to occur. As a result, the coldest January on record in Stockholm , in 1987, was also the sunniest. Accumulations of snow and ice are commonly associated with winter in

3432-548: The dance are made by men. Each year, a new corral is made and is placed at the entrance of the dance, with its entrance facing east. The Bear Dance is traditionally directed by a medicine man or chief. The basic dance step, called mamakwanika in Ute (English: back-and-forth dance), involves a back-and-forth motion, meant to emulate bears scratching a tree. During the dance, women are the ones who choose their male dance partner. Partners dance across from each other, without touching, for

3510-455: The drivers of the start and end of hibernation for bears. This study built the first chronology of both ecological and physiological events from before the start to the end of hibernation in the field. This research found that bears would enter their den when snow arrived and ambient temperature dropped to 0 °C. However, physical activity, heart rate, and body temperature started to drop slowly even several weeks before this. Once in their dens,

3588-634: The earliest suggested instance of hibernation being in Thrinaxodon , an ancestor of mammals that lived roughly 252 million years ago. The evolution of endothermy allowed animals to have greater levels of activity and better incubation of embryos, among other benefits for animals in the Permian and Triassic periods. In order to conserve energy, the ancestors of birds and mammals would likely have experienced an early form of torpor or hibernation when they were not using their thermoregulatory abilities during

3666-580: The end of the event, dancers can leave feathers or fringe from their outfits by the entrance of the corral, symbolizing the leaving of worries, pain, or bad luck in the past. The Bear Dance continues to be performed by the Ute People in the 21st century, primarily in Colorado and Utah and often in a shorter four day format. Some Ute now hold the dance around Memorial Day weekend, in May, so as to align with

3744-435: The first two days, and are allowed to touch while dancing for the last two days. The dance leader, known as the "Cat Man", touches couples with a willow stick to note when they are allowed to touch. Two different traditions exist regarding a dancer falling: one says that a fallen dancer marks the end of the dance; another says if dancers fall, they should remain on the ground until an elder blesses them. According to tradition,

3822-586: The highest rate of precipitation as well as prolonged dampness because of permanent snow cover or high precipitation rates coupled with low temperatures, precluding evaporation. Blizzards often develop and cause many transportation delays. Diamond dust , also known as ice needles or ice crystals, forms at temperatures approaching −40 °C (−40 °F) due to air with slightly higher moisture from above mixing with colder, surface-based air. They are made of simple hexagonal ice crystals. The Swedish Meteorological Institute (SMHI) defines thermal winter as when

3900-449: The hole is poorly insulated, the lemur's body temperature fluctuates widely, passively following the ambient temperature; if well insulated, the body temperature stays fairly constant and the animal undergoes regular spells of arousal. Dausmann found that hypometabolism in hibernating animals is not necessarily coupled with low body temperature. Historically it was unclear whether or not bears truly hibernate, since they experience only

3978-484: The individual's body-condition. Before entering hibernation, animals need to store enough energy to last through the duration of their dormant period, possibly as long as an entire winter. Larger species become hyperphagic , eating a large amount of food and storing the energy in their bodies in the form of fat deposits. In many small species, food caching replaces eating and becoming fat. Some species of mammals hibernate while gestating young, which are born either while

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4056-458: The insulating effects of snow by being buried in it. Larger plants, particularly deciduous trees , usually let their upper part go dormant, but their roots are still protected by the snow layer. Few plants bloom in the winter, one exception being the flowering plum , which flowers in time for Chinese New Year . The process by which plants become acclimated to cold weather is called hardening . Humans are sensitive to winter cold, which compromises

4134-527: The last day of February. In many countries in the Southern Hemisphere , including Australia , New Zealand , and South Africa , winter begins on 1 June and ends on 31 August. In Celtic nations such as Ireland (using the Irish calendar ) and in Scandinavia, the winter solstice is traditionally considered as midwinter, with the winter season beginning 1 November, on All Hallows , or Samhain . Winter ends and spring begins on Imbolc , or Candlemas , which

4212-459: The late 20th century, since it is dissimilar from hibernation seen in rodents. Obligate hibernators are animals that spontaneously, and annually, enter hibernation regardless of ambient temperature and access to food. Obligate hibernators include many species of ground squirrels , other rodents , European hedgehogs and other insectivores , monotremes , and marsupials . These species undergo what has been traditionally called "hibernation":

4290-402: The lower altitude of the Sun causes the sunlight to hit the Earth at an oblique angle. Thus a lower amount of solar radiation strikes the Earth per unit of surface area. Furthermore, the light must travel a longer distance through the atmosphere, allowing the atmosphere to dissipate more heat. Compared with these effects, the effect of the changes in the distance of the Earth from the Sun (due to

4368-548: The lowest average temperatures. This corresponds to the months of December, January and February in the Northern Hemisphere , and June, July and August in the Southern Hemisphere . The coldest average temperatures of the season are typically experienced in January or February in the Northern Hemisphere and in June, July or August in the Southern Hemisphere. Nighttime predominates in the winter season, and in some regions, winter has

4446-666: The mother hibernates or shortly afterwards. For example, female black bears go into hibernation during the winter months in order to give birth to their offspring. The pregnant mothers significantly increase their body mass prior to hibernation, and this increase is further reflected in the weight of the offspring. The fat accumulation enables them to provide a sufficiently warm and nurturing environment for their newborns. During hibernation, they subsequently lose 15–27% of their pre-hibernation weight by using their stored fats for energy. Ectothermic animals also undergo periods of metabolic suppression and dormancy , which in many invertebrates

4524-400: The muscle, as well as regulate the transcription of a suite of genes that limit muscle wasting. A study by G. Edgar Folk, Jill M. Hunt and Mary A. Folk compared EKG of typical hibernators to three different bear species with respect to season, activity and dormancy, and found that the reduced relaxation (QT) interval of small hibernators was the same for the three bear species. They also found

4602-420: The old Julian equinox and solstice dates. Also, Valentine's Day (14 February) is recognized by some countries as heralding the first rites of spring, such as flowers blooming. The three-month period associated with the coldest average temperatures typically begins somewhere in late November or early December in the Northern Hemisphere and lasts through late February or early March. This "thermological winter"

4680-475: The polar regions differ from the date of the winter solstice and depend on latitude. They differ due to the variation in the solar day throughout the year caused by the Earth's elliptical orbit (see: earliest and latest sunrise and sunset ). The English word winter comes from the Proto-Germanic noun *wintru- , whose origin is unclear. Several proposals exist, a commonly mentioned one connecting it to

4758-413: The prevernal season as early as late January in mild temperate climates. To survive the harshness of winter, many animals have developed different behavioral and morphological adaptations for overwintering : Some annual plants never survive the winter. Other annual plants require winter cold to complete their life cycle; this is known as vernalization . As for perennials , many small ones profit from

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4836-560: The question of why hibernators may return periodically to normal body temperatures has plagued researchers for decades, and while there is still no clear-cut explanation, there are multiple hypotheses on the topic. One favored hypothesis is that hibernators build a " sleep debt " during hibernation, and so must occasionally warm up to sleep. This has been supported by evidence in the Arctic ground squirrel . Other theories postulate that brief periods of high body temperature during hibernation allow

4914-529: The schedules of schoolchildren and workers. Others push the dance further back into the summer, leading to what some dub a "Bear Dance season" that stretches from April into September. The event is generally open to the public. During the COVID-19 pandemic , the 2020 Bear Dance was cancelled, with Utes using social media to share photos and videos of previous Bear Dances. Some musicians performed Bear Dance chants in "otherwise empty arenas", so people could come hear

4992-429: The season, but seasonal lag means that the coldest period normally follows the solstice by a few weeks. In some cultures, the season is regarded as beginning at the solstice and ending on the following equinox . In the Northern Hemisphere, depending on the year, this corresponds to the period between 20, 21 or 22 December and 19, 20 or 21 March. In an old Norwegian tradition, winter begins on 14 October and ends on

5070-408: The songs even if dancing did not occur. In 2021, some groups put on a "pared down" Bear Dance, with COVID-19 screenings, encouraging of face masks, and vaccine distribution. Ute children often learn about the dance and its etiquette at school. Some modern adaptations include the use of technology both to promote the event and during the event, such as the use of loudspeakers. The master of ceremonies

5148-452: The songs played by the Ute show respect to the bears spirits. Instruments used include wooden notched sticks, musical rasps, and drums. The songs are meant to sound like bears scratching and growling. When the drums are played, they sing an incantation. They believe the incantation takes the noises to the caves of the bears which are then transformed into thunder. Following the ceremony, recreational dancing, socializing, and feasting occur. At

5226-512: The southerly Patagonia region of South Argentina. Snow occurs year-round in Antarctica . In the Northern Hemisphere , some authorities define the period of winter based on astronomical fixed points (i.e., based solely on the position of the Earth in its orbit around the Sun), regardless of weather conditions. In one version of this definition, winter begins at the winter solstice and ends at

5304-434: The spring. These species have evolved freeze tolerance mechanism such as antifreeze proteins . Hibernation induction trigger (HIT) proteins isolated from mammals have been used in the study of organ recovery rates. One study in 1997 found that delta 2 opioid and hibernation induction trigger (HIT) proteins were not able to increase the recovery rate of heart tissue during ischemia. While unable to increase recovery rates at

5382-412: The term hibernal for this period of the year (the other ecological seasons being prevernal, vernal, estival, serotinal, and autumnal). The hibernal season coincides with the main period of biological dormancy each year whose dates vary according to local and regional climates in temperate zones of the Earth. The appearance of flowering plants like the crocus can mark the change from ecological winter to

5460-488: The term "seed hibernation" to refer to a form of seed dormancy . There is a variety of definitions for terms that describe hibernation in mammals, and different mammal clades hibernate differently. The following subsections discuss the terms obligate and facultative hibernation. The last two sections point out in particular primates, none of whom were thought to hibernate until recently, and bears, whose winter torpor had been contested as not being "true hibernation" during

5538-801: The time of ischemia, the protein precursors were identified to play a role in the preservation of veterinary organ function. Recent advances in recombinant protein technology make it possible for scientists to manufacture hibernation induction trigger (HIT) proteins in the laboratory without the need for animal euthanasia. Bioengineering of proteins can aid in the protection of vulnerable populations of bears and other mammals that produce valuable proteins. Protein sequencing of HIT proteins, such as α 1-glycoprotein-like 88 kDa hibernation-related protein HRP, contributes to this research pool. A study in 2014 utilizes recombinant technology to construct, express, purify, and isolate animal proteins (HP-20, HP-25, and HP-27) outside of

5616-444: The timing and extent of the seasonal diapause seem particularly variable, currently evolving as a response to climate change . As typical with hibernation, it evolved after the increased influence of seasonality as arthropods colonized terrestrial environments as a mechanism to keep energy costs low, particularly in harsher than normal environments, as well as being a good way to time the active or reproductive periods in arthropods. It

5694-440: The transition from ectothermy to endothermy. This is opposed to the previously dominant hypothesis that hibernation evolved after endothermy in response to the emergence of colder habitats. Body size also had an effect on the evolution of hibernation, as endotherms which grow large enough tend to lose their ability to be selectively heterothermic, with bears being one of very few exceptions. After torpor and hibernation diverged from

5772-403: The winter tend to have higher survival rates and slower aging. Reptiles evolved to exploit their ectothermy to deliberately cool their internal body temperatures. As opposed to mammals or birds, which will prepare for their hibernation but not directly cause it through their behavior, reptiles will trigger their own hibernation through their behavior. Reptiles seek out colder temperatures based on

5850-536: The winter. The mechanism for evolution of metabolic suppression in fish is unknown. Most fish that are dormant in the winters save enough energy by being still and so there is not a strong selective pressure to develop a metabolic suppression mechanism like that which is necessary in hypoxic conditions. Winter Winter is the coldest and darkest season of the year in polar and temperate climates . It occurs after autumn and before spring . The tilt of Earth's axis causes seasons; winter occurs when

5928-422: Was known to hibernate until the discovery of hibernation in the fat-tailed dwarf lemur of Madagascar, which hibernates in tree holes for seven months of the year. Malagasy winter temperatures sometimes rise to over 30 °C (86 °F), so hibernation is not exclusively an adaptation to low ambient temperatures. The hibernation of this lemur is strongly dependent on the thermal behaviour of its tree hole: If

6006-499: Was once thought that basking sharks settled to the floor of the North Sea and became dormant, but research by David Sims in 2003 dispelled this hypothesis, showing that the sharks traveled long distances throughout the seasons, tracking the areas with the highest quantity of plankton . Epaulette sharks have been documented to be able to survive for three hours without oxygen and at temperatures of up to 26 °C (79 °F) as

6084-414: Was possible in early hominid species. As the ancestors of birds and mammals colonized land, leaving the relatively stable marine environments, more intense terrestrial seasons began playing a larger role in animals' lives. Some marine animals do go through periods of dormancy, but the effect is stronger and more widespread in terrestrial environments. As hibernation is a seasonal response, the movement of

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