Octopuses are known to sleep and to change color while they do it. Now, a study published on March 25, 2021, in the journal iScience finds that these color changes are characteristic of two major alternating sleep states: an “active sleep” stage and a “quiet sleep” stage. The researchers say that the findings have implications for the evolution of sleep and might indicate that it’s possible for octopuses to experience something akin to dreams.
Scientists used to think that only mammals and birds had two sleep states. More recently, it was shown that some reptiles also show non-REM and REM sleep. A REM-like sleep state was reported also in cuttlefish, a cephalopod relative of the octopus.
“That led us to wonder whether we might see evidence of two sleep states in octopuses, too,” says senior author Sidarta Ribeiro of the Brain Institute of the Federal University of Rio Grande do Norte, Brazil. “Octopuses have the most centralized nervous system of any invertebrate and are known to have a high learning capacity.”
To find out, the researchers captured video recordings of octopuses in the lab. They found that during ‘quiet sleep’ the animals were still and quiet, with pale skin and eye pupils contracted to a slit. During ‘active sleep,’ it was a different story. The animals dynamically changed their skin color and texture. They also moved their eyes while contracting their suckers and body with muscular twitches.
“What makes it more interesting is that this ‘active sleep’ mostly occurs after a long ‘quiet sleep’ — generally longer than 6 minutes — and that it has a characteristic periodicity,” Ribeiro says.
The cycle would repeat at about 30- to 40-minute intervals. To establish that these states indeed represented sleep, the researchers measured the octopuses’ arousal threshold using visual and tactile stimulation tests. The results of those tests showed that in both ‘active’ and ‘quiet sleep’ states, the octopuses needed a strong stimulus to evoke a behavioral response in comparison with the alert state. In other words, they were sleeping.
The findings have interesting implications for octopuses and for the evolution of sleep. They also raise intriguing new questions.
“The alternation of sleep states observed in the Octopus insularis seems quite similar to ours, despite the enormous evolutionary distance between cephalopods and vertebrates, with an early divergence of lineages around 500 million years ago,” says first author and graduate student Sylvia Medeiros of the Brain Institute of the Federal University of Rio Grande do Norte, Brazil.
“If in fact two different sleep states evolved twice independently in vertebrates and invertebrates, what are the essential evolutionary pressures shaping this physiological process?” she asks. “The independent evolution in cephalopods of an ‘active sleep’ analogous to vertebrate REM sleep may reflect an emerging property common to centralized nervous systems that reach a certain complexity.”
Medeiros also says that the findings raise the possibility that octopuses experience something similar to dreaming. “It is not possible to affirm that they are dreaming because they cannot tell us that, but our results suggest that during ‘active sleep’ the octopus might experience a state analogous to REM sleep, which is the state during which humans dream the most,” she says. “If octopuses indeed dream, it is unlikely that they experience complex symbolic plots like we do. ‘Active sleep’ in the octopus has a very short duration — typically from a few seconds to one minute. If during this state there is any dreaming going on, it should be more like small videoclips, or even gifs.”
In future studies, the researchers would like to record neural data from cephalopods to better understand what happens when they sleep. They’re also curious about the role of sleep in the animals’ metabolisms, thinking, and learning.
“It is tempting to speculate that, just like in humans, dreaming in the octopus may help to adapt to environmental challenges and promote learning,” Ribeiro says. “Do octopuses have nightmares? Could octopuses’ dreams be inscribed on their dynamic skin patterns? Could we learn to read their dreams by quantifying these changes?”
Reference: “Cyclic alternation of quiet and active sleep states in the octopus” by Sylvia Lima de Souza Medeiros, Mizziara Marlen Matias de Paiva, Paulo Henrique Lopes, Wilfredo Blanco, Françoise Dantas de Lima, Jaime Bruno Cirne de Oliveira, Inácio Gomes Medeiros, Eduardo Bouth Sequerra, Sandro de Souza, Tatiana Silva Leite and Sidarta Ribeiro, 25 March 2021, iScience.
This work was supported by the State University of Rio Grande do Norte (UERN), the Coordenação de Aperfeicoamento de Pessoal de Nível Superior (CAPES), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), and from the São Paulo Research Foundation (FAPESP) Center for Neuromathematics.
NASA's Perseverance Mars Rover Extracts First Oxygen from Red Planet – Stockhouse
WASHINGTON , April 21, 2021 /PRNewswire/ — The growing list of “firsts” for Perseverance, NASA’s newest six-wheeled robot on the Martian surface, includes converting some of the Red Planet’s thin, carbon dioxide-rich atmosphere into oxygen. A toaster-size, experimental instrument aboard Perseverance called the Mars Oxygen In-Situ Resource Utilization Experiment ( MOXIE ) accomplished the task. The test took place April 20 , the 60th Martian day, or sol, since the mission landed Feb. 18 .
While the technology demonstration is just getting started, it could pave the way for science fiction to become science fact – isolating and storing oxygen on Mars to help power rockets that could lift astronauts off the planet’s surface. Such devices also might one day provide breathable air for astronauts themselves. MOXIE is an exploration technology investigation – as is the Mars Environmental Dynamics Analyzer ( MEDA ) weather station – and is sponsored by NASA’s Space Technology Mission Directorate (STMD) and Human Exploration and Operations Mission Directorate.
“This is a critical first step at converting carbon dioxide to oxygen on Mars,” said Jim Reuter , associate administrator for STMD. “MOXIE has more work to do, but the results from this technology demonstration are full of promise as we move toward our goal of one day seeing humans on Mars. Oxygen isn’t just the stuff we breathe. Rocket propellant depends on oxygen, and future explorers will depend on producing propellant on Mars to make the trip home.”
For rockets or astronauts, oxygen is key, said MOXIE’s principal investigator, Michael Hecht of the Massachusetts Institute of Technology’s Haystack Observatory.
To burn its fuel, a rocket must have more oxygen by weight. Getting four astronauts off the Martian surface on a future mission would require approximately 15,000 pounds (7 metric tons) of rocket fuel and 55,000 pounds (25 metric tons) of oxygen. In contrast, astronauts living and working on Mars would require far less oxygen to breathe. “The astronauts who spend a year on the surface will maybe use one metric ton between them,” Hecht said.
Hauling 25 metric tons of oxygen from Earth to Mars would be an arduous task. Transporting a one-ton oxygen converter – a larger, more powerful descendant of MOXIE that could produce those 25 tons – would be far more economical and practical.
Mars’ atmosphere is 96% carbon dioxide. MOXIE works by separating oxygen atoms from carbon dioxide molecules, which are made up of one carbon atom and two oxygen atoms. A waste product, carbon monoxide, is emitted into the Martian atmosphere.
The conversion process requires high levels of heat to reach a temperature of approximately 1,470 degrees Fahrenheit (800 Celsius). To accommodate this, the MOXIE unit is made with heat-tolerant materials. These include 3D-printed nickel alloy parts, which heat and cool the gases flowing through it, and a lightweight aerogel that helps hold in the heat. A thin gold coating on the outside of MOXIE reflects infrared heat, keeping it from radiating outward and potentially damaging other parts of Perseverance.
In this first operation, MOXIE’s oxygen production was quite modest – about 5 grams, equivalent to about 10 minutes worth of breathable oxygen for an astronaut. MOXIE is designed to generate up to 10 grams of oxygen per hour.
This technology demonstration was designed to ensure the instrument survived the launch from Earth, a nearly seven-month journey through deep space, and touchdown with Perseverance on Feb. 18 . MOXIE is expected to extract oxygen at least nine more times over the course of a Martian year (nearly two years on Earth).
These oxygen-production runs will come in three phases. The first phase will check out and characterize the instrument’s function, while the second phase will run the instrument in varying atmospheric conditions, such as different times of day and seasons. In the third phase, Hecht said, “we’ll push the envelope” – trying new operating modes, or introducing “new wrinkles, such as a run where we compare operations at three or more different temperatures.”
“MOXIE isn’t just the first instrument to produce oxygen on another world,” said Trudy Kortes , director of technology demonstrations within STMD. It’s the first technology of its kind that will help future missions “live off the land,” using elements of another world’s environment, also known as in-situ resource utilization .
“It’s taking regolith, the substance you find on the ground, and putting it through a processing plant, making it into a large structure, or taking carbon dioxide – the bulk of the atmosphere – and converting it into oxygen,” she said. “This process allows us to convert these abundant materials into useable things: propellant, breathable air, or, combined with hydrogen, water.”
More About Perseverance
A key objective of Perseverance’s mission on Mars is astrobiology , including the search for signs of ancient microbial life. The rover will characterize the planet’s geology and past climate, pave the way for human exploration of the Red Planet, and be the first mission to collect and cache Martian rock and regolith (broken rock and dust).
Subsequent NASA missions, in cooperation with ESA (European Space Agency), would send spacecraft to Mars to collect these sealed samples from the surface and return them to Earth for in-depth analysis.
The Mars 2020 Perseverance mission is part of NASA’s Moon to Mars exploration approach, which includes Artemis missions to the Moon that will help prepare for human exploration of the Red Planet.
NASA’s Jet Propulsion Laboratory in Southern California , which is managed for NASA by Caltech in Pasadena, California , built and manages operations of the Perseverance rover.
For more about Perseverance:
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Breathtaking NASA Image Shows a Magical ‘Sea of Dunes’ on Mars
It also shows wind-sculpted lines surrounding Mars’ frosty northern polar cap.
The section captured in the shot represents an area that is 31 kilometers (19 miles) wide, NASA said. The sea of dunes, however, actually covers an area as large as Texas.
The photo is a false color image, meaning that the colors are representative of temperatures. Blue represents cooler climes, and the shades of yellow mark out “sun-warmed dunes,” the US space agency wrote.
The photo is made of a combination of images captured by the Thermal Emission Imaging System instrument on the Mars Odyssey orbiter, NASA wrote.
Captured during the period from December 2002 to November 2004, the breathtaking images have been released to mark the 20th anniversary of Odyssey.
The Mars Odyssey orbiter is a robotic spacecraft circling Mars that uses a thermal imager to detect evidence of water and ice on the planet.
It was launched in 2001, making it the longest-working Mars spacecraft in history.
Humans actually hunted large animals and ate mostly meat for 2 millions years: study – CTV News
Despite a widespread belief that humans owe their evolution to the dietary flexibility in eating both meat and vegetables, researchers in Israel suggest that early humans were actually apex predators who hunted large animals for two million years before they sought vegetables to supplement their diet.
In a study recently published in the American Journal of Physical Anthropology, academics from Tel Aviv University in Israel and the University of Minho in Portugal examined modern biology to determine if stone-age humans were specialized carnivores or generalist omnivores.
“So far, attempts to reconstruct the diet of Stone-Age humans were mostly based on comparisons to 20th century hunter-gatherer societies,” one of the study’s authors, Miki Ben-Dor, a researcher at Tel Aviv University, said in a press release.
“This comparison is futile, however, because two million years ago hunter-gatherer societies could hunt and consume elephants and other large animals – while today’s hunter gatherers do not have access to such bounty.”
Instead, the researchers looked at approximately 400 previous scientific studies on human anatomy and physiology as well as archeological evidence from the Pleistocene period, or “Ice Age” period, which began about 2.6 million years ago, and lasted until 11,700 years ago.
“We decided to use other methods to reconstruct the diet of Stone-Age humans: to examine the memory preserved in our own bodies, our metabolism, genetics and physical build,” Ben-Dor said.
“Human behaviour changes rapidly, but evolution is slow. The body remembers.”
They discovered 25 lines of evidence from the studied papers on human biology that seem to show that earlier Homo sapiens were apex predators at the top of the food chain.
For example, the academics explained that humans have a high acidity in their stomachs when compared to omnivores or even other predators, which is important for consuming animal products.
“Strong acidity provides protection from harmful bacteria found in meat, and prehistoric humans, hunting large animals whose meat sufficed for days or even weeks, often consumed old meat containing large quantities of bacteria, and thus needed to maintain a high level of acidity,” Ben-Dor said.
Another piece of evidence, according to the study, is the structure of human fat cells.
“In the bodies of omnivores, fat is stored in a relatively small number of large fat cells, while in predators, including humans, it’s the other way around: we have a much larger number of smaller fat cells,” Ben-Dor said.
In addition to the evidence they collected by studying human biology, the researchers said archeological evidence from the Pleistocene period supports their theory.
In one example, the study’s authors examined stable isotopes in the bones of prehistoric humans as well as their hunting practices and concluded these early humans specialized in hunting large and medium-sized animals with high fat content.
“Comparing humans to large social predators of today, all of whom hunt large animals and obtain more than 70% of their energy from animal sources, reinforced the conclusion that humans specialized in hunting large animals and were in fact hypercarnivores,” the academics noted.
Ben-Dor said Stone-Age humans’ expertise in hunting large animals played a major role in the extinction of certain large animals, such as mammoths, mastodons, and giant sloths.
“Most probably, like in current-day predators, hunting itself was a focal human activity throughout most of human evolution. Other archeological evidence – like the fact that specialized tools for obtaining and processing vegetable foods only appeared in the later stages of human evolution – also supports the centrality of large animals in the human diet, throughout most of human history,” he said.
This is not to say, however, that humans during this period didn’t eat any plants. Ben-Dor said they also consumed plants, but they weren’t a major component of their diet until the end of the era when the decline of animal food sources led humans to increase their vegetable intake.
Eventually, the researchers said humans had no choice but to domesticate both plants and animals and become farmers.
Ran Barkai, one of the study’s authors and a professor at Tel Aviv University, said their findings have modern-day implications.
“For many people today, the Paleolithic diet is a critical issue, not only with regard to the past, but also concerning the present and future. It is hard to convince a devout vegetarian that his/her ancestors were not vegetarians, and people tend to confuse personal beliefs with scientific reality,” he said.
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