Recent research shows that jellyfish share surprising similarities with humans, including a sleep pattern of approximately eight hours a day, complemented by short naps. Understanding the sleep behaviors of these marine creatures can shed light on the evolutionary significance of sleep.
“Interestingly, like humans, jellyfish spend about a third of their time sleeping,” states Lior Appelbaum from Bar-Ilan University in Israel.
In animals with brains, such as mammals, sleep is crucial for memory consolidation and the elimination of metabolic waste. However, it remains unclear why sleep evolved in jellyfish, which belong to the brainless cnidarian group and possess neurons arranged in simple networks.
Appelbaum and his team utilized high-resolution cameras to observe Cassiopeia Andromeda, an upside-down jellyfish, in a controlled aquarium environment. The jellyfish were subjected to cycles of light and darkness to replicate natural conditions.
During the simulated daytime, the jellyfish exhibited an average pulse rate of over 37 times per minute, demonstrating responsiveness to sudden stimuli. In contrast, their pulse rate decreased at night, and they became less reactive, indicating a sleep state. These pulsations are vital for nutrient distribution and oxygen supply within the jellyfish’s body, as explained by Appelbaum.
Overall, jellyfish typically sleep for about eight hours each night, interspersed with brief naps lasting one to two hours. Prior studies had confirmed nocturnal sleep in C. Andromeda, but the intricacies of their sleep cycles were previously unknown.
In another experiment, researchers simulated sleep disruption by pulsating water against the jellyfish, which led to even better sleep the following day. “It mirrors human behavior: when sleep-deprived at night, we tend to feel more fatigued during the day,” notes Appelbaum.
Crucially, further examination indicated that sleep in C. Andromeda is associated with reduced DNA damage. Sleep likely protects neurons from deterioration that might occur during wakefulness, as corroborated by the observation that exposing jellyfish to ultraviolet light—thereby increasing DNA damage—resulted in improved sleep patterns.
Future studies are required to determine whether similar sleep benefits apply to other jellyfish species or even mammals. The researchers also found comparable results with starlet sea anemones (Nematostella vectensis), marking a significant step in confirming sleep in these organisms, according to Appelbaum.
Recent Observations of the M87* Black Hole by the Event Horizon Telescope (EHT) – Eight Ground-Based Radio Telescopes (ALMA, APEX, Iram 30 m Telescope, James Clerk Maxwell Telescope, Lage Millimeter Telescope Alfonso Serrano, Submillimeter Array Telescope) – Unveil a dynamic environment with varying polarization patterns near black holes.
The EHT images show that the magnetic field of M87* spiraled in one direction in 2017, settled in 2018, and reversed direction in 2021. Image credit: EHT collaboration.
Messier 87 is a vast elliptical galaxy situated approximately 53 million light-years away in the Virgo constellation.
This galaxy, also known as M87, houses the M87*, an ultra-massive black hole with a mass exceeding 6 billion solar masses.
In 2017, the EHT Collaboration detected a helical polarization pattern, indicating large-scale twisted magnetic structures, confirming long-held hypotheses about black hole interactions and their surrounding environments.
However, by 2018, the polarization nearly vanished. In 2021, a faint remnant began to spiral in the opposite direction.
Astrophysicists are now grappling with the pivotal question: Why?
“Black holes hold mysteries tightly, yet we continue to seek answers from their grasp,” stated Professor Avery Broderick, an astrophysicist at the University of Waterloo and the Perimeter Institute.
“Our team at Waterloo is reconstructing images from EHT data and determining what we can confidently assert—distinguishing between realistic findings and potential instrumental artifacts.”
“We are at the forefront of deciphering how EHT images, particularly their evolution, can unveil astrophysical dramas unfolding in the most extreme gravitational conditions.”
Each year, EHT collaborations revisit M87*, capturing fleeting moments that reveal its ongoing evolution, providing deeper insights into its well-guarded secrets.
“What’s intriguing is that the ring sizes have remained consistent over the years, validating the shadows of black holes predicted by Einstein’s theory, while the polarization patterns change dramatically,” remarked Dr. Paul Thierde, an astronomer at the Harvard & Smithsonian Center for Astrophysics.
“This indicates that the magnetized plasma swirling near the event horizon is not static but dynamic and complex, challenging theoretical models.”
The stability of M87*’s shadow serves as evidence that “black holes have no hair,” implying that a black hole is a simple geometric entity defined exclusively by mass, spin, or charge.
“This simplicity makes it an intriguing object of study within gravity, allowing for precise predictions. Other astrophysical phenomena seem secondary,” elaborated Professor Broderick.
“However, the surrounding environment can exhibit ‘hair,’ with magnetic fields being notable examples.”
“We have long understood what types of magnetic structures could exist, but now we believe there’s a rich diversity of configurations that can change rapidly, similar to human hairstyles.”
“These findings illustrate how EHT is maturing into a full-fledged scientific observatory that not only produces unprecedented images but also fosters a continuous and coherent understanding of black hole physics.”
“Each new observational campaign broadens our understanding, from the dynamics of plasma and magnetic fields to the role of black holes in the evolution of cosmic structures.”
“This is a concrete demonstration of the extraordinary scientific potential of this infrastructure.”
The survey results will be published in the journal Astronomy and Astrophysics.
____
Kazunori Akiyama et al. (Event Horizon Telescope Collaboration). 2025. 2017-2021 Horizon scale variation of M87* from EHT observations. A&A in press; doi: 10.1051/0004-6361/202555855
“When you search for stock market prices, you may see patterns…”
Muhla1/Getty Images
Flipping through the front page of a newspaper, one is greeted by a myriad of numbers—metrics about populations, lengths, areas, and more. If you were to extract these figures and compile them into a list, it might seem like a random assortment.
However, these figures are not as arbitrary as they may appear. In reality, the leading digit of many numbers, such as total revenues or building heights, tends to be predominantly the number 1. While true randomness would suggest that each digit has an equal chance of leading, the actual data shows that about one-third of the time, the first digit is a 1. The number 9, interestingly, appears as the leading digit in about 5% of cases, with other digits following such a trend.
This phenomenon is referred to as Benford’s Law, which illustrates the expected distribution of first digits within a dataset of a certain type—especially those spanning a wide, unspecified range. Although values like human height (where numbers are confined within a limited spectrum) or dates (which also have defined limits) don’t follow this law, others do.
Consider checking your bank balance, numbering a house, or analyzing stock prices (as displayed). Such numbers commonly exhibit a distribution with varied digit lengths. In neighborhoods with just a handful of houses, you might see a balance of numbers, whereas in larger towns, hundreds may share similar leading digits.
Picture a street hosting nine houses. The proportion of leading digits resembles an even split among the nine options. Conversely, on a street with 19 houses, a larger fraction—often over fifty percent—will begin with 1. As the housing number increases, this pattern persists. With 100 houses, you would observe a fairly uniform distribution across all digits, yet with 200 occupants, once again, more than half will typically start with 1.
Due to the diverse origins of data in real-world collections, the average likelihood of seeing numbers that start with 1 fluctuates between these two extremes. Similar calculations can be made for other digits, resulting in an overall frequency distribution observable in extensive datasets.
This characteristic is particularly useful in identifying potential data fabrication. When analyzing a company’s financial records, a Benford-like distribution is expected in their sales figures. However, when someone generates random numbers, the frequency distribution of the leading digits lacks a defined curve. This principle serves as one of the many tools forensic accountants employ to root out dubious activities.
The next time you examine your bank statement or compare river lengths, take note of how often those numbers start with 1.
Katie Steckles is a mathematician, lecturer, YouTuber, and author based in Manchester, UK. She also contributes advice to Brent Wister, a puzzle column for New Scientist. Follow her @stecks
For additional projects, please visit newscientist.com/maker
Origami “Bloom” design unfolds into a flower-like structure
BYU Photos
A novel collection of origami-like petal structures may enhance the design of various systems, including telescopes and solar panels.
These origami structures, rooted in the traditional art of Japanese paper folding, are favored by engineers for their ability to collapse into compact forms while expanding into larger configurations. However, the complexity of some origami patterns can pose challenges in deployment.
Recently, Larry Howell from Brigham Young University in Utah and his team have introduced a new category of origami shapes known as Bloom Patterns, which unfurl in a single, smooth motion to create a bowl-like design resembling a flower. “We can develop innovative designs that have never existed before, all while crafting aesthetically pleasing forms,” Howell notes.
Although certain Bloom patterns were recognized by origami aficionados and scholars before, Howell and his colleagues identified them as part of a broader spectrum of shapes with shared attributes.
By categorizing the different variations of Bloom patterns and providing a mathematical framework for their functioning, the researchers successfully constructed operational versions using various materials, including thick acrylic and plastics, demonstrating that each shape can consistently unfold.
The ability to deploy everything at once presents a significant advantage for space structures, minimizing the risk of complete failure during the process, states Michael Bartlett from Virginia Tech. “Every component must function perfectly; if one element fails, the entire operation is compromised,” he emphasizes. “When I observe these [Bloom patterns], it becomes evident that deployment does not follow a strict sequential pattern to achieve full expansion.”
While space telescopes generally rely on flatter mirrors for observation, the curved geometry of the Bloom pattern can facilitate the deployment of dishes akin to those in ground-based telescopes, yielding more precise imaging, Howell explains.
Having a mathematical model detailing the unfolding mechanism of these Bloom patterns could expedite the design process for functional origami structures, remarks Jamie Pike from the Swiss Federal Institute of Technology in Lausanne. “This provides us with insights to better anticipate the appearance of potential inventions and determine whether to pursue a certain direction or explore alternatives.”
The lines of galaxies that emerged after the collision of the two dwarf galaxies, which tore gases from one another.
Keim et al./Decals
A curious dwarf galaxy may have originated from a bullet-like collision in the universe.
Michael Keim from Yale University and his team employed the Keck Observatory in Hawaii to examine the distinctive trails of 12 small dwarf galaxies located approximately 75 million light-years from the Milky Way.
The orientation and velocity of the galaxies indicate that they resulted from a head-on impact between two galaxies known as NGC 1052-DF2 and NGC 1052-DF4. This collision expelled gas, which eventually coalesced into a group of stars due to gravitational attraction.
“They’re exceptionally unique,” states Kayme. “This is the only known system of its kind.”
Keim and his colleagues named this system after a similar cluster of large galaxies referred to as Bullet Clusters.
It is believed that the two galaxies collided at a speed of 350 kilometers per second around 9 billion years ago. As they passed through one another, gas was stripped from each galaxy. “While it’s improbable for two stars to collide,” notes Kayme, “the same does not apply to gas clouds.”
Interestingly, the remnants of stars left after the collision appear to lack dark matter. This is quite unusual, as most galaxies contain a substantial amount of dark matter, often comprising over 90% of their total mass.
Keim and his team theorize that this anomaly may stem from dark matter’s inability to interact with regular matter during the gas stripping process or because it remained unaffected by the interaction.
This finding may challenge alternative theories regarding dark matter, which posit that discrepancies in stellar and galactic behavior stem from gravitational effects rather than the existence of dark matter particles. “This suggests that dark matter is indeed a particle that can be separated from a galaxy,” explains Kayme.
Research has revealed a significant decline in the use of evidence-based language in American political speeches since the 1970s.
Findings published in the journal Natural human behavior stemmed from an analysis of over 8 million speeches delivered in the US Congress over the last 140 years.
“We wanted to understand why some politicians who frequently lie are perceived as honest,” stated Dr. Segun Aroyehun, the lead author of the study and a postdoctoral researcher at the University of Constance in Germany, as quoted in BBC Science Focus. “Often, it is because they speak about their beliefs and come across as genuine.”
Earlier research by Aroyehun and colleagues highlighted a shift in language usage among US Congress members towards belief-driven and intuitive language, departing from evidence-based language.
“There is a clear distinction between evidence-based truth and intuitive truth, where emotions play a crucial role,” Aroyehun explained.
To delve deeper, the team probed historical records to ascertain if this shift was a recent occurrence.
Utilizing machine learning models, the researchers combed through almost 150 years of Congress speeches, establishing a scoring system based on keywords signifying evidence-based or intuition-based language.
While evidence-based keywords comprised terms like “analysis”, “data”, “study results”, and “study”, intuition-based language included phrases such as “perspective”, “common sense”, “prediction”, and “believe”.
Both Republicans and Democrats have exhibited similar language changes in their political speeches over the past 140 years. – Getty
Each speech was assessed based on the evidence-intuition language ratio.
The results were striking. While the ratio fluctuated over the 140-year period, evidence-based language predominated until the 1940s, 1950s, and 1960s before a shift took place. Since the 1970s, intuition-based language has gradually gained prominence.
Aroyehun noted that this trend applied to both Democratic and Republican politicians, with a recent uptick observed in evidence-based language among Democrats.
He underscored that the ratio does not determine the veracity of the speech content.
Nonetheless, these linguistic shifts have had repercussions. The team juxtaposed these changes with measures of legislative polarization and income inequality, observing a simultaneous decline in parliamentary productivity—measured by statute quantity and quality—over this period.
“The core message here is the significance of rhetoric,” Aroyehun emphasized. “The nature of truth pursuit reflected in US Congress language is integral to gauging social and political well-being.”
The team aims to employ similar methodologies to analyze speeches in Germany and Italy, tracking trends across diverse democracies.
About our experts
Segun Aroyehun is a postdoctoral researcher affiliated with the Social Data Science Group at the University of Constance. He holds a PhD from Centro derestigación Computación, IPN, focusing on devising robust strategies to combat offensive content on social media. His research has been featured in publications like Natural human behavior and Natural Communication.
Humpback whale songs have statistical patterns in their structure, but they are very similar to those found in human language. This does not mean that songs convey complex meanings like our sentences, but that whales may learn songs in a similar way to how human infants begin to understand language. It suggests.
Only male humpback whales (Megaptera novaeangliae) When you sing, actions are considered important to attract peers. The songs are constantly evolving, and new elements appear and spread in the population until old songs are replaced with completely new ones.
“I think it's like a standardized test. Everyone has to do the same task, but changing or decorating to show that they're better at tasks than others can be done. You can do it.” Jenny Allen At Griffith University, in the Gold Coast, Australia.
Instead of trying to find meaning in songs, Allen and her colleagues were looking for innate structural patterns similar to those found in human language. They analyzed eight years of whale songs recorded around New Caledonia in the Pacific Ocean.
The researchers began by creating alphanumeric codes to represent all the songs on every recording, including a total of around 150 unique sounds. “Essentially it's a different sounding group, so maybe a year will make a groaning cry. So we may have an AAB.
Once all the songs were encoded, a team of linguists had to understand how best to analyze so much of the data. The breakthrough occurred when researchers decided to use an analytical technique that applies to methods of discovering words called transition probability.
“The speech is continuous and there is no pause between words, so infants must discover the boundaries of the word.” Invalanon At Hebrew University in Jerusalem. “To do this, use low-level statistics. Specifically, if they are part of the same word, the sounds are more likely to occur together. Infants Use these dips in the possibility of discovering the boundaries of words following another sound.”
For example, the phrase “cute flower” intuitively recognizes that the syllable “pre” and “tty” are more likely to go together than “tty” or “flow.” “If there is a similar statistical structure in a whale song, these cues should also help segment it,” Arnon says.
Using the alphanumeric version of Whale Song, the team calculated the probability of transition between successive sound elements and cut it when the previous sound elements were amazing.
“These cuts divide the song into segmented subsequences,” Arnon says. “We then looked at their distribution and, surprisingly, discovered that they follow the same distribution as seen in all human languages.”
In this pattern called Zipfian distribution, the prevalence of less common words drops in a predictable way. Another impressive finding is that the most common whale sounds tend to be shorter, as is the case with the most common human language.
Nick Enfield At the University of Sydney, who was not involved in the research, it says it is a novel way to analyze whale songs. “What that means is when you analyze it War and peacethe most frequent words are the next twice as often, and researchers have identified similar patterns in whale songs,” he says.
Team Members Simon Carby The University of Edinburgh in the UK says he didn't think this would work. “I will never forget the moment the graph appears. It appears to be familiar from human language,” he says. “This has made me realize that it uncovered a deep commonality between these two species, separated by tens of millions of years of evolution.”
However, researchers emphasize that this statistical pattern does not lead to the conclusion that whale songs are languages that convey meaning as we understand them. They suggest that the possible reason for commonality is that both whale songs and human languages are culturally learned.
“The physical distribution of words and sounds in languages is a truly fascinating feature, but there are millions of other things about languages that are completely different from whale songs,” Enfield says.
In another study It was released this week, Mason Young Blood At Stony Brook University in New York, we found that other marine mammals may also have structural similarities to human language in communication.
Menzeras' law predicting that sentences with more words should consist of shorter words were present in 11 of the 16 species of disease studied. The ZIPF abbreviation law was discovered in two of the five types in which the available data can now be detected.
“To sum up, our research suggests that humpback whale songs have evolved to be more efficient and easier to learn, and that these features can be found in the level of notes within the phrase, phrases within the song. I'm doing it,” Youngblood says.
“Importantly, the evolution of these songs is also biological and cultural. Although some features, such as Menzerath's Law, can emerge through the biological evolution of voice devices, Other features such as the rank frequency method of ZIPF are [the Zipfian distribution]there may be times when cultural communication of songs between individuals is necessary,” he says.
In the new study, archaeologists analyzed five inscribed artifacts from the Paleolithic period in central Levantin. Two engraved levalovacores from the Manot and Kahuze caves, engraved plackets from the site of Kneitra, and flakes and cortical blades from the Amdo caves. Their findings highlight the intentionality behind the sculpture and provide important insights into the development of abstract thinking and the cultural complexity of mid-Paleolithic society.
Carved cortical revarova core of the Manot Cave. Image credit: E. Ostrovsky/M. Smelansky/E. Paixão/L. Schunk.
Until now, the intentionality of central Paleolithic incised stone artifacts has been widely accepted and not fully supported by empirical testing.
Many archaeologists view these marks as functional and were created through the use of tools or natural wear.
Being skeptical of the existence of abstract or symbolic thinking in early hominins, understanding that symbolic actions such as art and abstract expressions appear much later than human evolution and are particularly relevant to modern people. I have.
Current research challenges the view by providing evidence of intentional and symbolic sculptures before global colonization by modern humans.
This study focuses on artifacts from major Levantin sites, including Dr. May Goldberger, an archaeologist at Hebrew and Ben Gurion University, as well as the outdoor sites of Manot Cave, Amdo Cave, Kahuze Cave and Queneitra. I guessed it.
Using advanced 3D surface analysis, the researchers examined the shape and pattern of the incision to distinguish intentional engraving from functional marks.
The findings reveal significant differences. The artifacts of Manot, Kahuze and Queneitra feature careful sculptures with geometric patterns that match the surface topography, highlighting aesthetic and symbolic intent.
In contrast, the incisions of artifacts from Amud Cave are shallow and unscattered, consistent with their functional use as an appraider.
“Abstract thinking is the basis of human cognitive evolution,” said Dr. Goder-Goldberger.
“The intentional sculpture found in these artifacts emphasizes the ability to represent symbolic representation and proposes a society with high conceptual capabilities.”
“The methodology we employed not only emphasize the intentional nature of these sculptures, but also provides for the first time a comparative framework for studying similar artifacts, enriching understanding of mid-term paleolithic society.” Zentrum für Archäogie, University of Johannes Gutenberg, University of Algarve.
“The inscribed artifacts of Qafzeh, Queneitra, and Manot are isolated initiatives within time series and geographical contexts, but the similarity of the shared properties and pattern structure of the incision itself suggests intentional and pre-determined behavior. I am.
“These findings provide a greater understanding of symbolic behavior and provide important insights into the cognitive and cultural development of early hominins.”
“This study illustrates an important step in understanding the scope of our ancestors' symbolic behavior and bridging the gap between the use of functional tools and abstract representation.”
Team paper Published in the journal Archaeological and anthropological sciences.
____
M. Goder-Goldberger et al. 2025. An incised stone craft from the complexity of ancient stones and human behavior in the central Levantin. Archaeol Anthropol Sci 17, 27; doi:10.1007/s12520-024-02111-4
In a new study, paleontologists used synchrotron X-ray tomography of annual growth in dental cementum from fossil mammals belonging to three Jurassic animal groups to elucidate the origin of mammalian growth patterns that are intrinsically linked to mammals being warm-blooded.
“This is the first time we've been able to reconstruct the growth patterns of early mammals in such detail,” said Dr Elise Newnham, a postdoctoral researcher at Queen Mary, University of London and the University of Bonn.
“By studying the spacing and texture of these growth rings, we can not only tell us how fast they grew at different stages of their life, but also make inferences about their metabolism and overall lifespan.”
The study calls into question previous assumptions about the growth patterns of our mammalian ancestors and the idea that these animals may have grown in a way similar to modern mammals.
Instead, the study answers a question raised by similar recent studies of early mammalian ancestors: when did modern mammalian life cycles evolve?
The researchers found that the first signs of modern mammalian growth patterns — high growth rates in young animals that stop at puberty — began in the earliest true mammals about 130 million years ago, compared with relatively little change throughout their lives in previously evolved mammalian forms.
However, like mammals, these animals grow slower and live much longer than modern small mammals such as mice and mice, with a maximum lifespan of 8 to 14 years.
The timing of this change in growth rate, combined with changes in tree-ring structure, indicates when these animals reached puberty and possibly sexual maturity.
“These data suggest that while all living small mammals reach sexual maturity within a few months of birth, the earliest mammals took several years to reach sexual maturity, supporting the results of a recent study on one of our study animals. Cruxatodon” Dr Pam Gill, a researcher at the Natural History Museum and University of Bristol, said:
“What's more, we find that this long, drawn-out life history was common to early mammals throughout the Jurassic Period.”
“Our results suggest that distinctive mammalian life history traits, such as high metabolic rate and extended parental care, evolved gradually over millions of years,” Dr Newnham said.
“The Jurassic period appears to have been a pivotal period in this evolution.”
The researchers used a technique called synchrotron X-ray tomography to image tiny growth rings in fossilized root cementum, the bone tissue that attaches teeth to the jaw. These rings are similar to those found in trees, but on a microscopic scale.
By counting the growth rings and analysing their thickness and texture, they were able to reconstruct the growth patterns and lifespan of the extinct animals.
“This work is a great example of how new technologies are revolutionizing our understanding of the distant past,” said Professor Thomas Martin from the University of Bonn.
“By closely examining these fossilized teeth, we can gain valuable insight into the lives of organisms that lived millions of years ago.”
“We are incredibly excited to be involved in this project,” said researcher Dr Jen Bright, from the University of Hull.
“Putting Jurassic fossils in a particle accelerator (synchrotron) to reconstruct the past sounds like science fiction, but it's actually possible!”
This skull belonged to Homo erectus, the first human species to leave Africa about 2.1 million years ago. When Homo erectus migrated from Africa, the climate in the northeast of the continent was wetter and more lush than it is today, according to a new study. Climate cycles combined to form green corridors, which our early ancestors likely took advantage of during migration. Credit: Mizmareck / FlickrThe green corridor that runs through the Sahara desert emerged just as our ancestors migrated from Africa. This is shown by the following new research. Aarhus University.About 6 million years ago, something amazing happened in the deep forests of eastern Africa. Chimpanzees, our closest relatives in the animal kingdom, evolved in one direction, while our first ancestors continued to evolve in another direction.Over the next millions of years, the differences between early humans and chimpanzees grew larger and larger. Our ancestors climbed down from trees and began walking upright on two legs, freeing their hands to use tools.This was the beginning of a development that would end with humanity conquering most of the Earth.About 2.1 million years ago, the first humans, Homo erectus, migrated from Africa. The journey took them through northeastern Africa and the Middle East (areas today mostly covered in desert), and on to Europe and Asia.Black dots in the Mediterranean indicate where sediment cores were collected. This area is supplied with terrestrial material from northeastern Africa, but the landscape and vegetation changed under the influence of the African Wet Period.Credit: Nature Communications Earth and EnvironmentFor years, researchers have speculated about how Homo erectus was able to traverse the arid, unforgiving desert with no food, water or shade.New research from Aarhus University suggests Homo erectus may not have been walking through deserts when it left Africa, says Rachel Lupien, one of the researchers who contributed to the new results. explain.“We know that there are repeated periods of changing climate in the Sahara Desert. We call this phenomenon the “Green Sahara” or the “African Wet Period.” During the green season, the desert shrinks significantly, transforming into a landscape resembling the East African savanna we know today,” she says, adding:”Our results show that the Sahara was greener at the very time Homo erectus first migrated than at any time in the 4.5 million years we studied. most likely could have walked through the green corridor outside.”the race that conquered the worldThe first humans were seed Homo erectus appeared in eastern Africa more than 2 million years ago.Homo erectus was the first hominin to learn how to carve an ax out of stone. These axes were probably used as weapons for killing prey and cutting meat from bones. They were probably also the first to learn how to control fire.Homo erectus was slightly shorter than modern humans, but more muscular. They had wider hips and elongated skulls. Additionally, their brains were significantly smaller, about half the size of ours.For more than 1.5 million years, Homo erectus lived and spread throughout most of the planet. From Africa, through Europe and Asia, across the Strait of Malacca to some islands in Indonesia. This made Homo erectus the longest-lived human species. We, Homo sapiens, evolved about 300,000 years ago.sauce: natural history museumThe ocean floor reveals past climateThe Sahara Desert as we know it today is in one of its dry seasons. The duration of these periods varies, but approximately every 20,000 years, the continent goes through both wet and dry cycles. These rainy seasons are what Rachel Lupyan has called “Africa’s wet seasons.””How wet it gets during the wet green period varies. In fact, there are two other cycles involved, one lasting 100,000 years and one lasting 400,000 years. So , over a period of 100,000 years, the wet period will vary, becoming wetter or drier than usual. The same is true for 400,000-year intervals,” says Rachel Lupyan.But how do we actually know what Africa’s climate was like hundreds of thousands of years ago?The ocean floor tells us, and for this very reason, we actually already know a lot about past climates, she explains.”Using core samples from the Mediterranean Sea, we can learn what the climate was like millions of years ago. Layers of sediment have formed on the ocean floor, and these layers contain Small molecules can tell us a great deal about what the climate was like in the past.”Substances that make leaves shineOver time, material ejected from North Africa forms a new layer on the ocean floor that slowly descends across the ocean. Therefore, the buried ocean floor acts as a kind of logbook that can tell us what the climate was like in the past.The layer has a set of biomarkers that store information about past climate. One of these markers is a set of molecules that plants use to protect their leaves. They are also called leaf wax, explains Rachel Lupyan.”Waxes coat trees, bushes, and blades of grass, making them shine. When a plant dies, most parts of the plant decompose rapidly, but wax molecules can survive for long periods of time. That is why such molecules are often found in sediments that are millions of years old.”The chemical composition of wax molecules can tell us what the climate was like when that layer formed. For example, the hydrogen molecules in the wax can give some information about how much precipitation there was.“Water contains hydrogen, so hydrogen can be used to circulate water. Water on Earth contains both regular hydrogen and deuterium (deuterium). “When it rains a lot, plants can absorb relatively less deuterium, but when it’s dry they absorb more,” she says.Carbon holds important knowledgeRachel Lupyan and her colleagues could tell by the amount of deuterium in the wax of leaves during wet and dry times. But hydrogen doesn’t tell us anything about which plants grew in humid climates.But it is present in the carbon atoms found in leaf wax, she explains.“There are two main types of plants. We also refer to them as C3 and C4 plants,” she says.”About 90 percent of all plants are C3 plants. They live in most areas of the earth, except in extremely dry or very hot regions. C4 plants, on the other hand, They specialize in surviving in areas with high temperatures.”C3 and C4 plants produce leaf wax containing different amounts of heavy carbon, allowing researchers to distinguish between them in samples. In this way, you can “read” which types of plants were most dominant at the time.”At the time Homo erectus migrated out of Africa, more C3 was detected in samples than during any other humid period in the past 4.5 million years. It shows a change to grassland or savannah,” she says.3 types of photosynthesisBroadly speaking, there are three different methods in the plant kingdom. photosynthesis. There is a C3 plant, a C4 plant, and his third variant called the CAM plant.90% of all plants are C3 plants, 6% are CAM plants, and only 3-4% are C4 plants. However, this is not the case in Africa. In Africa, vast grasslands have a much higher proportion of C4 plants.Differences among plants are due to different coping strategies when moisture in the air or soil is limited.When it gets too dry, C3 plants close the small stomata in their leaves and absorb CO2. When the hole closes, the plant can no longer photosynthesize and begins burning stored carbon, expelling water and carbon dioxide. If this continues for too long, the plant will die.On the other hand, C4 plants can photosynthesize even in dry conditions. Even though the stomata are closed, they continue to convert CO2 into energy. They can do this with the help of a molecule with four carbon atoms, which gives the plant species its name. CAM plants use his third method and can cope even with drier regions.Wheat, oats, rice, and sunflowers are examples of C3 plants. His known C4 plants are corn, sugar cane, and amaranth, while succulents, cacti, and pineapple are his CAM plants.sauce: khan academy, biology dictionary and rex.dkGreenest 2.1 million years agoGreen periods in Africa, similar to ice ages in northern latitudes, are caused by small fluctuations in the Earth’s orbit around the sun. Geologists call these fluctuations Milankovitch cycles.And two of these changes in particular will play an important role as the Sahara desert receives more rainfall, explains Rachel Lupyan.”The Earth wobbles a bit in its orbit around the sun.…
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