News Article | February 15, 2017
An ancient continent that was once sandwiched between India and Madagascar now lies scattered on the bottom of the Indian Ocean. The first clues to the continent’s existence came when some parts of the Indian Ocean were found to have stronger gravitational fields than others, indicating thicker crusts. One theory was that chunks of land had sunk and become attached to the ocean crust below. Mauritius was one place with a powerful gravitational pull. In 2013, Lewis Ashwal at the University of the Witwatersrand in South Africa and his colleagues proposed that the volcanic island was sitting on a piece of old, sunken continent. Although Mauritius is only 8 million years old, some zircon crystals on the island’s beaches are almost 2 billion years old. Volcanic eruptions may have ejected the zircon from ancient rock below. Now, Ashwal and his team have found zircon crystals in Mauritius that are up to 3 billion years old. Through detailed analyses they have reconstructed the geological history of the lost continent, which they named Mauritia. Until about 85 million years ago, Mauritia was a small continent — about a quarter of the size of Madagascar — nestled between India and Madagascar, which were much closer than they are today. Then, India and Madagascar began to move apart, and Mauritia started to stretch and break up. “It’s like plasticine: when continents are stretched they become thinner and split apart,” says Martin Van Kranendonk at the University of New South Wales in Australia. “It’s these thin pieces that sink below the ocean.” There is evidence that other volcanic islands in the Indian Ocean, including the Cargados Carajos, Laccadive and Chagos islands, also sit on fragments of Mauritia. More and more remnants of other old continents are being uncovered, says Alan Collins at the University of Adelaide in Australia. Several pieces have recently been found off Western Australia and underneath Iceland, he says. “It’s only now as we explore more of the deep oceans that we’re finding all these bits of ancient continents around the place.”
News Article | March 2, 2017
Elephants sleep an average of two hours a day — the shortest-known sleep time of any mammal on land, a new study has found. They also regularly go almost two days without shuteye, a research team from the University of the Witwatersrand in South Africa discovered. African elephants are the largest terrestrial animal, and evidence suggests that larger mammals are likely to sleep less. Many other studies, however, only probed their sleep in captive environments and also mistook mere rest for sleep. Lead researcher and professor Paul Manger and his colleagues tracked two free-roaming African elephant matriarchs living in Botswana’s Chobe National Park for 35 days. They outfitted the subjects with an actiwatch — much like the fitness and health tracker Fitbit — to monitor sleep accurately and a GPS collar with a gyroscope to track and monitor position. “[M]easuring the activity of the trunk, the most mobile and active appendage of the elephant, would be crucial, making the reasonable assumption that if the trunk is still for five minutes or more, the elephant is likely to be asleep,” said Manger in a statement. The two elephants turned out to sleep two hours a day on average, with the sleep occurring mostly at pre-dawn. They went without sleep for up to 46 hours, traveling long distances of about 30 kilometers during those times, likely because of threats such as poaching or predation. According to data, sleep in these wild creatures appear to be unrelated to sunrise or sunset, but rather are tied to environmental factors such as temperature and humidity. They could also sleep while either standing up or lying down, which happened only every three or four days and for around an hour. It was in lying down that the elephants could reach rapid eye movement (REM) or dream sleep, which is believed to be vital for memory consolidation. “The elephant has well-documented long-term memories,” explained Manger, “but does not need REM sleep every day to form these memories.” The findings were discussed in the journal PLOS ONE. Probing sleep in animals proves critical not only for stumbling upon new information for better wildlife conservation and management practices. In an important nature reserve in Central Africa, researchers recently found that around 25,000 or 81 percent of the forest elephant population had been wiped out by poaching. The remote, 2,900-square-mile Minkébé in Gabon, supposedly the frontliner in the battle against poaching that buoys the ivory demand in Asia, saw its elephant population disappearing fast from 2004 to 2014. It is threatened not just by Gabonese poachers, but by hunters from neighboring nations such as Cameroon. These animal sleep studies also offer a better understanding of our own sleep as humans. While it remains a mystery why we sleep, new research considers sleep a way to forget certain things learned throughout the day in order to grow neural connections that will store new memories. A four-year experiment detected the shrinking of synapses or neural connections in mice while they slept, therefore positioning sleep as a way for the brain to keep learning new things and forming new memories. © 2017 Tech Times, All rights reserved. Do not reproduce without permission.
News Article | February 15, 2017
Africa is a tough place. It always has been. Especially if you have to fend off gigantic predators like sabre-toothed carnivores in order to survive. And, when you're a small, dog-sized pre-mammalian reptile, sometimes the only way to protect yourself against these monsters is to turn your saliva into a deadly venomous cocktail. That is exactly what a distant, pre-mammalian reptile, the therapsid Euchambersia, did about 260 million years ago, in order to survive the rough conditions offered by the deadly South African environment. Living in the Karoo, near Colesberg in South Africa, the Euchambersia developed a deep and circular fossa, just behind its canine teeth in the upper jaw, in which a deadly venomous cocktail was produced, and delivered directly into the mouth through a fine network of bony grooves and canals. "This is the first evidence of the oldest venomous vertebrate ever found, and what is even more surprising is that it is not in a species that we expected it to be, " says Dr Julien Benoit, researcher at the Bernard Price Institute for Palaeontological Research at the University of the Witwatersrand in South Africa. "Today, snakes are notorious for their venomous bite, but their fossil record vanishes in the depth of geological times at about 167 million years ago, so, at 260 million years ago, the Euchambersia evolved venom more than a 100 million years before the very first snake was even born. " As venom glands don't fossilise, Benoit and his colleagues from at Wits University, in association with the Natural History Museum of London used cutting edge CT scanning and 3D imagery techniques to analyse the only two fossilised skulls of the Euchambersia ever found, and discovered stunning anatomical adaptions that are compatible with venom production. Their results were published in the open access journal, PlosOne, in February. "First, a wide, deep and circular fossa (a space in the skull) to accommodate a venom gland was present on the upper jaw and was connected to the canine and the mouth by a fine network of bony grooves and canals," says Benoit. "Moreover, we discovered previously undescribed teeth hidden in the vicinity of the bones and rock: two incisors with preserved crowns and a pair of large canines, that all had a sharp ridge. Such a ridged dentition would have helped the injection of venom inside a prey. " Unlike snakes like vipers or cobras, which actively inject their prey with venom through needle-like grooves in their teeth, the Euchambersia's venom flowed directly into its mouth, and the venom was passively introduced into its victim through ridges on the outside of its canine teeth. "Euchambersia could have used its venom for protection or hunting. Most venomous species today use their venom for hunting, so I would rather go for this option. In addition, animals at that time were not all insectivorous, particularly among therapsids, which were very diverse." The first Euchambersia fossil was found in 1932, and the second in 1966. The two fossils were both found on the farm Vanwyksfontein, near Colesberg in the Eastern Cape, and while they were found more than 34 years apart from each other, for millions of years, they were lying only a few metres apart. The life and times of the Euchambersia According to measurements of the two fossils, the Euchambersia was a small dog-like pre-mammalian reptile that grew between 40 and 50cm long, and lived well before the first dinosaur even appeared. What is intriguing is that Euchambersia is related to early mammals, not snakes. More and more venom producing mammals are discovered every year, including shrews and primates like the Loris of South East Asia. Researchers believe that mammals that lived millions of years ago used to be venomous, but lost this ability in time. However, in some mammals, the genes responsible for venom production were activated again at a later stage. The first evidence of snakes date back to 167 million years ago. There are two hypotheses as to how and when snakes became venomous. The first suggests that snakes like cobras and vipers became venomous independently about 20 million years ago. However, other researchers suggest that the common ancestors of snakes and lizards became venomous about 250 million years ago, which means the Euchambersia became venomous about 100 million years before snakes did.
News Article | February 14, 2017
Africa is a tough place. It always has been. Especially if you have to fend off gigantic predators like sabre-toothed carnivores in order to survive. And, when you're a small, dog-sized pre-mammalian reptile, sometimes the only way to protect yourself against these monsters is to turn your saliva into a deadly venomous cocktail. That is exactly what a distant, pre-mammalian reptile, the therapsid Euchambersia, did about 260 million years ago, in order to survive the rough conditions offered by the deadly South African environment. Living in the Karoo, near Colesberg in South Africa, the Euchambersia developed a deep and circular fossa, just behind its canine teeth in the upper jaw, in which a deadly venomous cocktail was produced, and delivered directly into the mouth through a fine network of bony grooves and canals. "This is the first evidence of the oldest venomous vertebrate ever found, and what is even more surprising is that it is not in a species that we expected it to be, " says Dr Julien Benoit, researcher at the Bernard Price Institute for Palaeontological Research at the University of the Witwatersrand in South Africa. "Today, snakes are notorious for their venomous bite, but their fossil record vanishes in the depth of geological times at about 167 million years ago, so, at 260 million years ago, the Euchambersia evolved venom more than a 100 million years before the very first snake was even born. " As venom glands don't fossilise, Benoit and his colleagues from at Wits University, in association with the Natural History Museum of London used cutting edge CT scanning and 3D imagery techniques to analyse the only two fossilised skulls of the Euchambersia ever found, and discovered stunning anatomical adaptions that are compatible with venom production. Their results were published in the open access journal, PLOS One, in February. "First, a wide, deep and circular fossa (a space in the skull) to accommodate a venom gland was present on the upper jaw and was connected to the canine and the mouth by a fine network of bony grooves and canals," says Benoit. "Moreover, we discovered previously undescribed teeth hidden in the vicinity of the bones and rock: two incisors with preserved crowns and a pair of large canines, that all had a sharp ridge. Such a ridged dentition would have helped the injection of venom inside a prey. " Unlike snakes like vipers or cobras, which actively inject their prey with venom through needle-like grooves in their teeth, the Euchambersia's venom flowed directly into its mouth, and the venom was passively introduced into its victim through ridges on the outside of its canine teeth. "Euchambersia could have used its venom for protection or hunting. Most venomous species today use their venom for hunting, so I would rather go for this option. In addition, animals at that time were not all insectivorous, particularly among therapsids, which were very diverse."
News Article | March 1, 2017
Why we sleep is one of the enduring unanswered mysteries of modern science. Along with such activities as eating, protecting oneself and reproducing, sleep is one of the major biological imperatives of existence. Although being asleep precludes these other activities, all animals do sleep. Some, like whales, dolphins, seals and certain birds, do it in a very unusual manner, sleeping with only half their brain at a time, while some sleep quite a lot and others less so. "While there are many hypotheses regarding the function of sleep, the ultimate purpose of sleep is yet to be discovered," says Prof. Paul Manger, from the School of Anatomical Sciences at Wits University. The lack of sleep can -- even over a relatively short term - lead to brain damage, and in the longer term death, as can be seen in the human conditions fatal familial insomnia and sporadic fatal insomnia. Generally, larger animals tend to sleep less than smaller animals, but do elephants fit this trend? Behavioural studies of elephant sleep in zoos record that they sleep around four hours per day and can sleep standing up or lying down -- but how much do they sleep and how do they sleep in their natural environment? Working in the Chobe national Park in Botswana, Manger, Dr Nadine Gravett and Dr Adhil Bhagwandin at the University of the Witwatersrand, along with their colleagues from the NGO Elephants Without Borders, Botswana, and the University of California, Los Angeles, made use of small activity data loggers, scientific versions of the well-known consumer fitness and wellness tracker, Fitbit, to study the sleeping patterns of elephants in the wild. "We reasoned that measuring the activity of the trunk, the most mobile and active appendage of the elephant, would be crucial, making the reasonable assumption that if the trunk is still for five minutes or more, the elephant is likely to be asleep," says Manger. The team outfitted two matriarch elephants, noting when they used their trunk by an implanted activity data logger, when they moved around and - by installing a GPS collar with a gyroscope around their necks - where and when they were lying down to sleep. The main finding of the study, recently published in the journal PLOS ONE, was that the two matriarch elephants slept only two hours per day on average, and this sleep occurred mostly in the early hours of the morning, well before dawn. "The data also indicates that environmental conditions (temperature and humidity, but not sunlight) are related to when the elephants fell asleep and when they woke up (which happens well before dawn)," says Manger. "This finding is the first that indicates that sleep in wild animals is likely not to be related to sunrise and sunset, but that other environmental factors are more crucial to the timing of sleep." The team also found that the wild elephants could sleep while standing up, or while lying down. Lying down to sleep only happened every three or four days and for about an hour, and it is likely that when the elephants were lying to sleep were the only times they could go into REM, or dreaming, sleep, meaning elephants possibly don't dream on a daily basis like we do, but may dream only every few days. "REM sleep (or dreaming) is thought to be important for consolidating memories, but our findings are not consistent with this hypothesis of the function of REM sleep, as the elephant has well-documented long-term memories, but does not need REM sleep every day to form these memories," says Manger. Lastly, they found that the two elephants, when disturbed by such things as predators, poachers, or a bull elephant in musth, could go without sleep for up to 48 hours, and following the start of the disturbance would walk up to 30 km from where the disturbance occurred. This put a great deal of distance between the elephant herd and any source of danger, but at the expense of a loss of a night's sleep. "Understanding how different animals sleep is important for two reasons. First, it helps us to understand the animals themselves and discover new information that may aid the development of better management and conservation strategies, and, second, knowing how different animals sleep and why they do so in their own particular way, helps us to understand how humans sleep, why we do, and how we might get a better night's sleep."
News Article | March 2, 2017
Wild African elephants sleep for the shortest time of any mammal, according to a study. Scientists tracked two elephants in Botswana to find out more about the animals' natural sleep patterns. Elephants in zoos sleep for four to six hours a day, but in their natural surroundings the elephants rested for only two hours, mainly at night. The elephants, both matriarchs of the herd, sometimes stayed awake for several days. During this time, they travelled long distances, perhaps to escape lions or poachers. They only went into rapid eye movement (REM, or dreaming sleep, at least in humans) every three or four days, when they slept lying down rather than on their feet. A way to lift an elephant's mood How to put an elephant to sleep Prof Paul Manger of the University of the Witwatersrand, South Africa, said this makes elephant sleep unique. "Elephants are the shortest sleeping mammal - that seems to be related to their large body size," he told BBC News. "It seems like elephants only dream every three to four days. Given the well-known memory of the elephant this calls into question theories associating REM sleep with memory consolidation." Elephants living in captivity have been widely studied. To find out more about their sleeping habits in the wild, Prof Manger and his research team fitted the scientific equivalent of a fitness tracker under the skin of the animals' trunks. The device was used to record when the elephants were sleeping, based on their trunk staying still for five minutes or more. The two elephants were also fitted with a gyroscope to assess their sleeping position. Both elephants were followed for five weeks, giving new insights into their natural sleep patterns. "We had the idea that elephants should be the shortest sleeping mammal because they're the largest," said Prof Manger. "Why this occurs, we're not really sure. Sleep is one of those really unusual mysteries of biology, that along with eating and reproduction, it's one of the biological imperatives. We must sleep to survive." Generally, smaller-bodied mammals sleep for longer than larger ones. For example, sloths sleep for around 14 hours a day, while humans sleep for around 8 hours. How elephants survive on so little sleep remains a mystery. The researchers are planning follow-up studies on more elephants, including males. They also want to find out more about REM sleep in elephants. REM sleep is believed to be critical in laying down memories. It is a type of sleep seen across the animal kingdom, in mammals and birds and even lizards. Most mammals go into REM sleep every day.
News Article | March 1, 2017
It’s another sleepless night in the savannah. Wild elephants average just 2 hours of sleep a night, making them the lightest-known snoozers of any mammal. Previous studies have looked at such habits in captive elephants, which sleep for 3 to 7 hours a day. But with more dangers and pressure to find food, wild animals tend to sleep less. So Paul Manger at the University of the Witwatersrand, Johannesburg in South Africa and his colleagues set out to monitor sleep in wild African elephants in Chobe National Park in northern Botswana. The most reliable way to measure sleep is to use electrical recordings of the brain, but this isn’t possible in elephants. Their thick skulls mean that surface electrodes are ineffective, and putting electrodes under the skull would require invasive surgery. Instead, the researchers fitted motion sensors to elephants’ trunks. The trunk is the most active part of the elephant’s body, and is rarely idle while the animal is awake. “We figured when it hadn’t been used for 5 minutes, the elephant was probably asleep,” says Manger. The team monitored two matriarchs for 35 continuous days. The elephants slept for an average of 2 hours a night, not in a single slumber but in four to five short bursts – a pattern known as polyphasic sleep. Most of their sleep occurred between 1.00 and 6.00 am, and the elephants snoozed in different places every night. On four days, the elephants didn’t get any shut-eye at all, resulting in them being awake for up to 48 hours continuously. During these periods, they travelled long distances of around 30 kilometres, possibly to evade lions or poachers. But they didn’t appear to compensate with extra sleep after going a night without. Although the sample size is very small, Manger thinks these findings give a reasonably reflective view of wild elephants’ typical sleep habits. “I think what we’ve got is pretty close to the mark,” he says. “Obviously it would be nice to do a lot more animals, but there are ethical considerations and the bottom line is getting enough funding.” The elephants also wore a collar with a gyroscope attached to it, which told the researchers whether they were standing up or lying down. Each elephant slept lying down on only 10 of the 35 days. This finding implies that the animals spent very little time in rapid-eye-movement (REM) sleep, the stage when we have vivid dreams that is thought to be important for memory consolidation. During REM, the muscles usually relax, making it impossible to remain standing. Either elephants only experience REM every few days, or they can enter this phase in short bursts of 5 to 10 seconds while standing, as birds do, says Manger. Alternatively, like whales and dolphins, they may not need REM at all. “We’re not sure which of those is true yet and that’s something we’d like to follow up and discover,” he says. Bigger animals generally tend to sleep less, probably because they have to spend so much time eating. “Elephants can eat up to 300 kilograms of food a day, so obviously it takes a long time for the trunk to get all that into their mouths, and that leaves less time for sleep,” says Manger. But even among large mammals, elephants seem to be light sleepers. The considerably larger grey whale sleeps for 9 hours a day and the giraffe for almost 5 hours. The domestic horse, at nearly 3 hours, is its closest rival. The use of trunk motion to infer sleep state is clever, says John Lesku at La Trobe University in Melbourne, Australia, but he adds that it will be important to learn more about how posture and trunk movement reflect waking, sleeping and REM sleep. “For instance, ruminants can stand, have their eyes partially open and even continue to chew their cud during non-REM sleep, raising the possibility that elephants might have more sleep than appreciated,” he says. Read more: Why brainy animals need more REM sleep after all; Sleep and dreaming: The how, where and why
News Article | March 2, 2017
—If you’ve ever felt tired and overworked, be thankful you’re not an elephant. The lumbering giants may get by on at little as two hours a night, according to scientists. The first sleep study of wild elephants, published in journal PLOS ONE on Wednesday, concluded that elephants may get less sleep than any other mammal, including new human parents. What’s more, they regularly skip nights and often sleep standing up, leaving little chance to dream. The research contributes to a growing understanding of the relationship between body size and sleep time, but complicates science’s quest to understand the ultimate purpose of sleep. Scientists had previously observed captive elephants sleeping 4 to 6 hours a day, but catching some extra z’s while unemployed and with nothing to do in an enclosed area perhaps isn’t so surprising. Wild animals have to feed themselves, avoid threats, and in the case of the two matriarch subjects of this study, lead their herd. "Sleep needs to be studied in an animal's natural environment if we are truly to understand it," said Paul Manger, a research professor in the School of Anatomical Sciences at the University of the Witwatersrand in South Africa who led the study, in an interview with Reuters. To get a more accurate picture of wild behavior, researchers tagged two female leaders known as matriarchs with a gyroscope-equipped GPS collar to track location and position, and surgically implanted a benign Fitbit-like movement tracker into each elephant’s trunk. Embedding an electrical device to monitor the brain directly into the animals’ thick skulls was deemed to be too invasive, so researchers used trunk movement as an approximation of wakefulness, the New Scientist reports. “We reasoned that measuring the activity of the trunk, the most mobile and active appendage of the elephant, would be crucial, making the reasonable assumption that if the trunk is still for five minutes or more, the elephant is likely to be asleep,” said Dr. Manger in a press release. The month-long study found that the elephants slept an average of two hours each day, a full hour less than the previous mammalian record holder, the domestic horse. Those two hours generally fell in the early hours before dawn and were spread out over four to five short nap sessions, like Spaniards but with more siestas. On multiple occasions, the animals walked through the night, staying awake for up to two days straight and covering distances as far as 19 miles. Researchers suspect they may have been avoiding predators such as lions or poachers. Unlike most humans, the elephants didn’t log any extra catch-up time the day after an all-nighter. When the giants did sleep, it was in a different spot each night, and often standing up. Because they only laid down for about an hour every three to four days, researchers concluded that elephants don’t enter REM sleep daily like humans. While dreaming, most mammals relax their muscles, making it difficult to stand. However, Manger told New Scientist that birds can dream in sub-minute bursts, and whales and dolphins appear to go without REM sleep entirely. Since this investigation only studied trunk movement, it’s impossible to know for sure when and if the elephants dreamt. “We’re not sure which of those is true yet and that’s something we’d like to follow up and discover,” he said. The short sleep time didn’t come as a surprise, though. The relationship between body size and sleep duration is still debated, but the authors used data on other captive plant-eating mammals to predict that elephants would sleep about 2.5 to 3 hours per day. It seems that larger animals tend to sleep less, perhaps because they have to spend so much time eating. What was more surprising was the possibility that elephants don’t dream very often. The purpose of sleep remains mysterious, but one proposed function is the re-writing of memories during REM. “REM sleep (or dreaming) is thought to be important for consolidating memories, but our findings are not consistent with this hypothesis of the function of REM sleep, as the elephant has well-documented long-term memories, but does not need REM sleep every day to form these memories,” said Manger. In the paper, the team wrote that the “current study has produced a number of exciting and interesting results,” but highlights a few potential biases in their data. The study recorded sleep times in only two individuals, and matriarchs at that. As any president can confirm, leaders don’t often get to sleep in. One was also nursing a 1-year-old calf. However, they also suspect that using trunk movement may have lead to an overestimate of sleep time, including those moments when the animal was motionless but hadn't yet drifted off. Despite these drawbacks, Manger thinks the team’s results are representative. “I think what we’ve got is pretty close to the mark,” he told New Scientist. “Obviously it would be nice to do a lot more animals, but there are ethical considerations and the bottom line is getting enough funding.
News Article | March 2, 2017
FILE PHOTO - A male elephant grazes during an exercise to fit them with advanced satellite radio tracking collar to monitor their movement and control human-wildlife conflict near Mt. Kilimanjaro at the Amboseli National Park, in Kenya on November 2, 2016. REUTERS/Thomas Mukoya/File Photo WASHINGTON (Reuters) - There's an old saying that elephants never forget. You also can say they almost never sleep. Scientists on Wednesday said a first-of-its-kind study tracking the sleep behavior of wild elephants found the world's largest land mammal sleeps two hours per day on average, and some days not at all, and does so mostly standing up. This represented the shortest-known sleep time of any mammal. Previous research showed captive elephants got four to six hours daily. "Sleep needs to be studied in an animal's natural environment if we are truly to understand it," said Paul Manger, a research professor in the School of Anatomical Sciences at the University of the Witwatersrand in South Africa who led the study published in the journal PLOS ONE. The researchers monitored two free-roaming female African elephants in Botswana's Chobe National Park for 35 days. They got data to track sleep accurately from a wristwatch-sized device implanted under the skin of the trunk that was not harmful to the animals. They used a satellite-tracking collar with a gyroscope to monitor their location and sleep position. "We do feel these two elephants are representative of the broader population," Manger said, adding he hoped future research could be done with larger numbers of wild elephants, including males. The elephants sometimes went up to 46 hours without sleep while walking distances of about 19 miles (30 km), possibly to avoid threats like lions or human poachers. They typically slept somewhere between 2 a.m. and 6 a.m. After a sleepless night, they had no extra sleep the next night. The maximum sleep recorded was five hours in a day. They spent just 17 percent of their sleeping time lying down. The next shortest sleepers among mammals may be domestic horses, which get under three hours daily. Some mammals have been shown in captivity to sleep most of the day, including the little brown bat (19 hours), opossum (18 hours) and armadillo (17 hours), Manger said. People average roughly six to nine hours, Manger said. The elephants appeared to experience rapid eye movement (REM) sleep, associated with more dreaming and body movements and loss of muscle tone, only every three to four nights. "REM sleep is often associated with the consolidation of memories. However, we do know elephants have good memories, so this finding contradicts one central hypothesis of REM sleep function," Manger said.
News Article | March 3, 2017
Fitbit-style tracking of two wild African elephants suggests their species could break sleep records for mammals. The elephants get by just fine on about two hours of sleep a day. Much of that shut-eye comes while standing up — the animals sleep lying down only once every three or four days, new data show. Most of what scientists previously knew about sleeping elephants came from captive animals, says neuroethologist Paul Manger of the University of the Witwatersrand, Johannesburg. In zoos and enclosures, elephants have been recorded snoozing about three hours to almost seven over a 24-hour period. Monitoring African elephants in the wild, however, so far reveals more extreme behavior. Data are hard to collect, but two females wearing activity recorders for about a month averaged less sleep than other recorded mammals. Especially intriguing is the elephants’ ability to skip a night’s sleep without needing extra naps later, Manger and colleagues report March 1 in PLOS ONE. “The remarkably short amount of sleep in wild elephants is a real elephant in the room for several theories for the function of sleep,” says Niels Rattenborg of the Max Planck Institute for Ornithology in Seewiesen, Germany. Ideas that sleep restores or resets aspects of the brain for peak performance can’t explain animals that sleep only a little and don’t need catch-up rest, says Rattenborg, who wasn’t involved in the elephant study. The results also don’t fit well with the thought that animals need sleep to consolidate memories. “Elephants are usually not considered to be forgetful animals,” he says. Before the latest elephant sleep stats, horses were the record-holders among mammals for the shortest sleep requirement at 2 hours, 53 minutes, Manger says. Donkeys weren’t far behind at 3 hours, 20 minutes. Game rangers familiar with wild African elephants, however, claimed the pachyderms virtually never slept. To investigate, Manger and colleagues implanted activity monitors in the trunks of the matriarchs of two herds in the Chobe National Park in northern Botswana. An implant about the size of a Fitbit activity tracker shouldn’t bother an elephant trunk, Manger says, because it’s “250 pounds of muscle.” Trunks, like human hands, are important for exploring and manipulating the world, so they’re rarely still for long. The researchers assumed that a trunk monitor motionless for at least five minutes probably meant the animal was asleep. Gyroscopes in neck collars helped researchers figure out whether animals were standing up or lying down. The trunk implants caught occasions when the matriarchs went as long as 46 hours without any form of sleep. A predator, poacher or a bull elephant loose in the neighborhood might explain the restlessness, Manger says. Animals in captivity don’t face the same dangers. African elephants’ low sleep requirements join a growing body of results showing that wild animals don’t need as much sleep as studies of captive animals suggest, Rattenborg says. His monitoring of wild sloths has revealed they aren’t as slothful as captives. And other work finds that great frigate birds and pectoral sandpipers still perform well on less than two hours of sleep a day. Still, it’s unclear how these findings for two females will translate to entire elephant populations. But the results do fit a trend that links larger species with shorter sleep and smaller species with longer sleep, Manger says. Some bats, for example, routinely sleep 18 hours a day. He and colleagues are toying with the idea that sleep duration might be related to a daily time budget. Bigger animals may sleep less as they need that time for tasks to sustain their size. Building and maintaining an elephant body, for example, may take more feeding time than maintaining a little bat body, Manger says.