Mar 20, 2018

Mars' oceans formed early, possibly aided by massive volcanic eruptions

The early ocean known as Arabia (left, blue) would have looked like this when it formed 4 billion years ago on Mars, while the Deuteronilus ocean, about 3.6 billion years old, had a smaller shoreline. Both coexisted with the massive volcanic province Tharsis, located on the unseen side of the planet, which may have helped support the existence of liquid water. The water is now gone, perhaps frozen underground and partially lost to space, while the ancient seabed is known as the northern plains.
A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million years earlier and were not as deep as once thought.

The proposal by geophysicists at the University of California, Berkeley, links the existence of oceans early in Mars history to the rise of the solar system's largest volcanic system, Tharsis, and highlights the key role played by global warming in allowing liquid water to exist on Mars.

"Volcanoes may be important in creating the conditions for Mars to be wet," said Michael Manga, a UC Berkeley professor of earth and planetary science and senior author of a paper appearing in Nature this week and posted online March 19.

Those claiming that Mars never had oceans of liquid water often point to the fact that estimates of the size of the oceans don't jibe with estimates of how much water could be hidden today as permafrost underground and how much could have escaped into space. These are the main options, given that the polar ice caps don't contain enough water to fill an ocean.

The new model proposes that the oceans formed before or at the same time as Mars' largest volcanic feature, Tharsis, instead of after Tharsis formed 3.7 billion years ago. Because Tharsis was smaller at that time, it did not distort the planet as much as it did later, in particular the plains that cover most of the northern hemisphere and are the presumed ancient seabed. The absence of crustal deformation from Tharsis means the seas would have been shallower, holding about half the water of earlier estimates.

"The assumption was that Tharsis formed quickly and early, rather than gradually, and that the oceans came later," Manga said. "We're saying that the oceans predate and accompany the lava outpourings that made Tharsis."

It's likely, he added, that Tharsis spewed gases into the atmosphere that created a global warming or greenhouse effect that allowed liquid water to exist on the planet, and also that volcanic eruptions created channels that allowed underground water to reach the surface and fill the northern plains.

Following the shorelines

The model also counters another argument against oceans: that the proposed shorelines are very irregular, varying in height by as much as a kilometer, when they should be level, like shorelines on Earth.

This irregularity could be explained if the first ocean, called Arabia, started forming about 4 billion years ago and existed, if intermittently, during as much as the first 20 percent of Tharsis's growth. The growing volcano would have depressed the land and deformed the shoreline over time, which could explain the irregular heights of the Arabia shoreline.

Similarly, the irregular shoreline of a subsequent ocean, called Deuteronilus, could be explained if it formed during the last 17 percent of Tharsis's growth, about 3.6 billion years ago.

"These shorelines could have been emplaced by a large body of liquid water that existed before and during the emplacement of Tharsis, instead of afterwards," said first author Robert Citron, a UC Berkeley graduate student. Citron will present a paper about the new analysis on March 20 at the annual Lunar and Planetary Science conference in Texas.

Tharsis, now a 5,000-kilometer-wide eruptive complex, contains some of the biggest volcanoes in the solar system and dominates the topography of Mars. Earth, twice the diameter and 10 times more massive than Mars, has no equivalent dominating feature. Tharsis's bulk creates a bulge on the opposite side of the planet and a depression halfway between. This explains why estimates of the volume of water the northern plains could hold based on today's topography are twice what the new study estimates based on the topography 4 billion years ago.

New hypothesis supplants old

Manga, who models the internal heat flow of Mars, such as the rising plumes of molten rock that erupt into volcanoes at the surface, tried to explain the irregular shorelines of the plains of Mars 11 years ago with another theory. He and former graduate student Taylor Perron suggested that Tharsis, which was then thought to have originated at far northern latitudes, was so massive that it caused the spin axis of Mars to move several thousand miles south, throwing off the shorelines.

Since then, however, others have shown that Tharsis originated only about 20 degrees above the equator, nixing that theory. But Manga and Citron came up with another idea, that the shorelines could have been etched as Tharsis was growing, not afterward. The new theory also can account for the cutting of valley networks by flowing water at around the same time.

"This is a hypothesis," Manga emphasized. "But scientists can do more precise dating of Tharsis and the shorelines to see if it holds up."

NASA's next Mars lander, the InSight mission (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport), could help answer the question. Scheduled for launch in May, it will place a seismometer on the surface to probe the interior and perhaps find frozen remnants of that ancient ocean, or even liquid water.

Read more at Science Daily

Fish accounted for surprisingly large part of the Stone Age diet

Sturgeon fish.
New research at Lund University in Sweden can now show what Stone Age people actually ate in southern Scandinavia 10 000 years ago. The importance of fish in the diet has proven to be greater than expected. So, if you want to follow a Paleo diet -- you should quite simply eat a lot of fish.

Osteologists Adam Boethius and Torbjörn Ahlström have studied the importance of various protein sources in the human diet across three millennia, from around 10 500 to 7 500 years ago. This was done by combining chemical analyses of human bones from over 80 individuals, whose skeletons are the oldest discovered in Scandinavia, with osteological analyses of animal bone material.

The study is part of a doctoral thesis that has used various methods to examine the significance of fishing for the people who settled in southern Scandinavia during the millenniums after the ice from the last ice age had melted away.

"At the Norje Sunnansund settlement, outside Sölvesborg in Sweden, you can see that just over half of the protein intake has come from fish, ten per cent from seals, and around 37 per cent from land mammals, such as wild boar and red deer, and scarcely three per cent from plants such as mushrooms, berries and nuts," says Adam Boethius. "On the island of Gotland, which did not have any land mammals apart from hares, the percentage of fish in total protein consumption was even higher at just under 60 per cent. Here, seals have replaced the land mammals and account for almost 40 per cent of the protein intake, whereas hares and vegetables account for a negligible proportion," he continues.

The study shows that fish was also a highly significant protein source on the Swedish west coast, but it seems that seals and dolphins were more important for the first pioneer settlers, and that after an initial focus on hunting aquatic mammals, fishing increased as a protein source.

Previously, the researchers believed that humans at that time had been far more involved in mobile groups of big-game hunters whose main protein intake thus should have come from herbivores such as red deer, aurochs and elk, and consequently the role of fishing was not recognised.

"The dominance of fishing is a discovery that has an enormous significance for our understanding of how people lived. Fishing is relatively stationary compared to the hunting of land mammals, which provides clear indications that settlements appeared in Scandinavia much earlier than researchers previously believed," says Adam Boethius.

The fact that researchers have often missed the significance of fishing is probably because they have not actively looked for the traces that exist. Fish bones are much smaller and more brittle than the bones of mammals, and are not as well preserved. In an excavation, fish bones are almost impossible to detect while in the ground and fine-mesh sieves must be used to find them.

The researchers found that fishing was surprisingly dominant at all the sites investigated. In the study, the individuals were divided up into those who lived in marine environments and those who lived in freshwater environments. In freshwater environments the protein intake is dominated by different types of carp fish species, perch, pike and burbot. Cod dominates in marine environments, but herring, saithe, haddock, spiny dogfish and plaice are also important species. On the other hand, migratory fish, such as eel and salmon, did not account for a large proportion of food intake.

"What's interesting is that the values from the people in the various groups do not overlap. This indicates that the groups had limited mobility and mostly lived on a local diet," says Adam Boethius.

The results also show that people become more dependent on fishing over time and that certain areas were probably more densely populated than previously thought.

"Even though fish can be caught in most lakes, there are certain places that are especially favourable. It is at these sites that the people begin to settle, creating their own territory. This probably entailed violent clashes between different groups of people, which is often reflected in the various violence-related injuries to the skeletons we find in archaeological excavations."

"The increasing importance of fish means that the land was divided up. For groups that continued to be mobile this meant the creation of no-go zones, that these groups were forced to skirt around in order to find food. In the long term this leads to increasing "costs" for foraging strategies and an increasing tendency to settle is to be expected, as it becomes the best alternative," concludes Adam Boethius.

More on the scientific model behind the findings:

Stable isotopes of the elements carbon and nitrogen are present in all parts of the human body, including the skeleton, and reflect a person's diet. By analysing these isotope signals for possible food sources and relating them to the values shown in human bone material, it is possible to deduce the diet the person in question has lived on.

Read more at Science Daily

Discovery of sophisticated 115,000-year-old bone tools in China

White bracket indicates the area where impact scars are present.
An analysis of 115,000-year-old bone tools discovered in China suggests that the toolmaking techniques mastered by prehistoric humans there were more sophisticated than previously thought.

Marks found on the excavated bone fragments show that humans living in China in the early Late Pleistocene were already familiar with the mechanical properties of bone and knew how to use them to make tools out of carved stone. These humans were neither Neanderthals nor sapiens.

This major find, in which Luc Doyon of UdeM's Department of Anthropology participated, has just been published in the scientific journal PLOS ONE.

"These artefacts represent the first instance of the use of bone as raw material to modify stone tools found at an East Asian early Late Pleistocene site,"said Doyon. "They've been found in the rest of Eurasia, Africa and the Levante, so their discovery in China is an opportunity for us to compare these artifacts on a global scale.

Until now, the oldest bone tools discovered in China dated back 35,000 years and consisted of assegai (spear) points. "Prior to this discovery, research into the technical behaviour of humans inhabiting China during this period was almost solely based on the study of tools carved from stone," said Doyon.

Three types of hammers

The seven bone fragments analyzed by Luc Doyon and his colleagues were excavated between 2005 and 2015 at the Lingjing site in central China's Henan province. The artifacts were found buried at a depth of roughly 10 metres. At the time, the site was being actively used as a water spring for animals. Prehistoric humans likely used these water supply points for killing and butchering their animal prey.

The bone fragments were dated using optically stimulated luminescence (OSL), a method widely used by geologists for dating the sediment layers in which tools are found.

Doyon explained that the researchers identified three types of bone retouchers, known as soft hammers, that were used to modify stone (or lithic) tools. The first type was weathered limb bone fragments, mainly from cervid metapodials, marginally shaped by retouching and intensively used on a single area. The second type was long limb bone flakes resulting from the dismemberment of large mammals, used for quick retouching or resharpening of stone tools. And the third type was a single specimen of an antler of an axis deer that, close to its tip, shows impact scars produced by percussing various lithic blanks.

The researchers have not yet determined which hominid species the users of these prehistoric tools belonged to, although they do know that they lived during the same period as Neanderthals and Homo sapiens. "The Lingjing site yielded two incomplete human skulls that suggest interbreeding between this species and Neanderthals," Doyon said. "But this is a hypothesis that remains to be confirmed through further investigation, such as paleogenetic studies."

More discoveries to come

The analyses that led to the identification of the bone tools were conducted by Doyon and his colleagues Francesco d'Errico (Université de Bordeaux), Li Zhanyang (Shandong University) and Li Hao (Chinese Academy of Sciences), at the Henan Provincial Institute for Cultural Relics and Archaeology.

Doyon participated in the project while working on his doctoral thesis on hunting weapons manufactured from osseous materials by the first Homo sapiens inhabiting Europe between 42,000 and 30,000 years ago. Having earned his PhD in anthropology from Université de Montréal in cotutelle with Université de Bordeaux (PhD in prehistory) in September 2017, Doyon will now pursue a postdoctoral fellowship at Shandong University to conduct further analyses on the bone tools discovered at the Lingjing site.

Read more at Science Daily

Interstellar asteroid, 'Oumuamua, likely came from a binary star system

This is an artist's impression of 'Oumuamua.
New research finds that 'Oumuamua, the rocky object identified as the first confirmed interstellar asteroid, very likely came from a binary star system.

"It's remarkable that we've now seen for the first time a physical object from outside our Solar System," says lead author Dr Alan Jackson, a postdoc at the Centre for Planetary Sciences at the University of Toronto Scarborough in Ontario, Canada.

A binary star system, unlike our Sun, is one with two stars orbiting a common centre.

For the new study, published in the journal Monthly Notices of the Royal Astronomical Society, Jackson and his co-authors set about testing how efficient binary star systems are at ejecting objects. They also looked at how common these star systems are in the Galaxy.

They found that rocky objects like 'Oumuamua are far more likely to come from binary than single star systems. They were also able to determine that rocky objects are ejected from binary systems in comparable numbers to icy objects.

"It's really odd that the first object we would see from outside our system would be an asteroid, because a comet would be a lot easier to spot and the Solar System ejects many more comets than asteroids," says Jackson, who specializes in planet and solar system formation.

Once they determined that binary systems are very efficient at ejecting rocky objects, and that a sufficient number of them exist, they were satisfied that 'Oumuamua very likely came from a binary system. They also concluded that it probably came from a system with a relatively hot, high mass star since such a system would have a greater number of rocky objects closer in.

The team suggest that the asteroid was very likely to have been ejected from its binary system sometime during the formation of planets.

'Oumuamua, which is Hawaiian for 'scout', was first spotted by the Haleakala Observatory in Hawaii on 19 October 2017. With a radius of 200 metres and travelling at a blistering speed of 30 kilometres per second, at its closest it was about 33,000,000 km from Earth.

When it was first discovered researchers initially assumed the object was a comet, one of countless icy objects that release gas when they warm up on approaching the Sun. But it didn't show any comet-like activity as it neared the Sun, and was quickly reclassified as an asteroid, meaning it was rocky.

Researchers were also fairly sure it was from outside our Solar System, based on its trajectory and speed. An eccentricity of 1.2 -- which classifies its path as an open-ended hyperbolic orbit -- and such a high speed meant it was not bound by the gravity of the Sun.

In fact, as Jackson points out, 'Oumuamua's orbit has the highest eccentricity ever observed in an object passing through our Solar System.

Major questions about 'Oumuamua remain. For planetary scientists like Jackson, being able to observe objects like these may yield important clues about how planet formation works in other star systems.

Read more at Science Daily

Mar 19, 2018

Hormone imbalance may explain higher diabetes rates in sleep-deprived men

Studies have found an association between insufficient sleep and the development of insulin resistance, one of the factors that cause type 2 diabetes, and now researchers have discovered a biological reason for this relationship, at least in men: an imbalance between their testosterone and cortisol hormones. The study results will be presented Sunday at ENDO 2018, the Endocrine Society's 100th annual meeting in Chicago, Ill.

"Our highly controlled sleep study showed that even one night of restricted sleep can cause insulin resistance and that we can dampen this effect by controlling levels of these two important hormones," said senior investigator Peter Y. Liu, M.B.B.S., Ph.D., a professor of medicine with the Los Angeles Biomedical (LA BioMed) Research Institute at Harbor-UCLA Medical Center, Torrance, Calif.

Insulin resistance occurs when the body does not properly use the hormone insulin. Testosterone is the main anabolic, or muscle-building, hormone, whereas cortisol -- often called the "stress hormone" -- helps catabolism, or breaking down energy and fat stores for use, Liu explained. Past research shows that sleep loss reduces a man's testosterone levels and increases cortisol levels.

Liu and his fellow researchers conducted five nights of sleep studies in 34 healthy men with an average age of 33. They controlled what the subjects ate and how much they slept, giving them 10 hours of sleep the first night and restricting them to four hours of sleep the remaining nights. The study received funding from the National Institutes of Health and the Clinical and Translational Research Center at LA BioMed.

In this "crossover" study, the men served as their own controls. In one series of sleep studies, they received three medications: ketoconazole, which switches off the body's production of testosterone and cortisol; testosterone gel; and oral hydrocortisone, a synthetic form of cortisol. The doses of testosterone and hydrocortisone were in the midrange of levels that the body normally produces, according to Liu. This arm of the study was called a dual "clamp" because it stopped the body's production of these two hormones and then gave them a fixed amount of the hormones, thus clamping levels in a normal hormonal balance, he said.

In another set of experiments, the men received inactive placebos that matched the medications. The order of when they received the clamp and the placebo was random, with a two-week interval between the study conditions. The morning after the first and last nights of each part of the study, all men took the oral glucose tolerance test, in which they gave blood samples while fasting and again after drinking a sugary drink. This test result allowed the researchers to calculate each man's insulin resistance using standard measures, including the Matsuda Index.

After sleep restriction, this index reportedly showed greater insulin resistance with both the clamp and the placebo. However, Liu said this increase was significantly dampened, or less severe, with the dual-clamp, demonstrating that testosterone and cortisol reduced the negative effects of sustained sleep restriction on insulin resistance.

Read more at Science Daily

New diabetes drug may help people with obesity lose weight

Diet pills.
A compound that mimics a naturally occurring hormone that regulates appetite may help people who have obesity but not diabetes to lose weight, a new study suggests. The research will be presented Sunday, March 18, at ENDO 2018, the Endocrine Society's 100th annual meeting in Chicago, Ill.

The compound, semaglutide, has a chemical structure that is very similar to the hormone glucagon-like peptide 1 (GLP-1), which regulates both insulin secretion and appetite. In December, the U.S. Food and Drug Administration approved the semaglutide injection Ozempic as a once-weekly adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes.

"This randomized study of weight loss induced with semaglutide in people with obesity but without diabetes has shown the highest weight reductions yet seen for any pharmaceutical intervention," said lead author Patrick M. O'Neil, Ph.D., Director of the Weight Management Center and Professor of Psychiatry and Behavioral Sciences at the Medical University of South Carolina in Charleston, S.C.

The new study included 957 participants, 35 percent of whom were male. All participants had a body mass index (BMI) of at least 30, but did not have diabetes. They were randomly assigned to seven different groups. Five groups received different doses of semaglutide (between 0.05 mg and 0.4 mg) via injection once daily; a sixth group received a placebo, and a seventh group received 3 mg of the diabetes drug liraglutide. All participants received monthly diet and exercise counseling.

After one year, all participants receiving semaglutide had lost significantly more weight than those receiving placebo. The higher the dose participants received, the greater their average weight loss. Participants who received 0.05 mg of semaglutide daily lost an average of 6.0 percent of their body weight; the 0.1 mg group lost an average of 8.6 percent; the 0.3 mg group lost an average of 11.2 percent; and those receiving a daily dose of 0.4 mg lost an average of 13.8 percent. Those receiving liraglutide lost an average of 7.8 percent of their body weight, while those in the placebo group lost only 2.3 percent on average.

Sixty five percent of participants who received 0.4 mg of semaglutide per day lost at least 10 percent of their body weight, compared with 10 percent of those in the placebo group and 34 percent of the liraglutide group.

Read more at Science Daily

NASA’s Kepler Space Telescope Is Nearing the End as Its Fuel Supply Runs Low

The Kepler mission, which launched in 2009, has transformed our understanding of our place in the galaxy, giving us hope that we aren’t alone. The venerable spacecraft has proved adept at reinventing itself when things go wrong. But engineers monitoring Kepler announced that the mission will soon come to an end because the spacecraft is running out of fuel.

“We’ve always known that Kepler’s lifetime would be limited by the amount of fuel in the tank,” said Thomas Barclay, a former senior research scientist with the Kepler and K2 missions.  “It looks like it’s going happen at some point in the next few months, although we still don’t know exactly when.”

Barclay said the timing of when the thruster fuel tank will be empty is somewhat difficult to estimate.

“We can’t actually measure how much fuel is left,” he told Seeker in a phone call. “The engineers have to measure how much pressure there is when the thrusters are fired. So it is a bit of an art to working out how much fuel there is and how long it will last. Even with the last little bit of fuel you don’t know if it will be useable or if it will be stuck in the bottom of the tank.”

Although the spacecraft team has long known about the fuel situation, Charlie Sobeck, a system engineer for Kepler made the announcement this week.

“The Kepler space telescope has survived many potential knock-outs during its nine years in flight, from mechanical failures to being blasted by cosmic rays,” Sobeck wrote. “At this rate, the hardy spacecraft may reach its finish line in a manner we will consider a wonderful success. But with nary a gas station to be found in deep space, the spacecraft is going to run out of fuel.”

But, Sobeck added: “We’ve been surprised by its performance before.”

Kepler revolutionized what we know about the amount of exoplanets in our galaxy.  The space-based telescope has detected 2,245 exoplanets with another 2,342 waiting to be confirmed.

Statistical analysis of data from the planet-hunting spacecraft reveals mind-boggling numbers: Our galaxy has at least 100 billion planets, and about 17 percent of stars have an Earth-sized planet. That means there are at least 17 billion Earth-sized worlds out there.

Kepler detected planetary candidates using the transit method, watching for a planet to cross its star and create a mini-eclipse that dims the star slightly. To do this in its Earth-trailing orbit 94 million miles away, Kepler needed to have precise pointing to constantly view a 100-square-degree portion of the sky — equivalent in size to two side-by-side “bowls” of the Big Dipper — in a star-filled region located between the constellations Cygnus and Lyra. 

The mission was a spectacular success, making the announcements of spectacular worlds orbiting other stars become almost routine.

But in May of 2013, a second of Kepler’s four reaction wheels failed. These gyroscope-like devices kept the spacecraft stable, and Kepler needed at least three to be able to point accurately enough to hunt for exoplanets.

But the spacecraft wasn’t dead yet. Engineers came up with a plan to use solar radiation pressure — the photons from the sun that can be used to power solar sails — to help stabilize that spacecraft.  While the telescope’s aim wasn’t as precise as it used to be, it was close. It remained a great telescope in space, and it just needed a new mission. So a group of scientists came up with a plan called K2, which Barclay described as a spectacular success in its own right.

“While the Kepler mission entailed a very focused science goal of finding exoplanets, K2 is a completely different beast,” he said. “We’re not just Kepler slightly worse at pointing; we were a revolutionary new mission.”

K2 has been run by the community of scientists around the world, one of the few NASA missions to lack a particular science goal.  Instead, a panel of scientists decides how the spacecraft will be used, choosing from submitted proposals.

Proposed missions are based on the 83-day region of sky where Kepler can point. 

Barclay led the K2 “guest observer” program that looked at everything from giant black holes to planets in our own solar system to supernovas in distant galaxies.

Kepler's thrusters are powered by hydrazine fuel, which has been used as a propellent since the early days of space flight. It's the same fuel that powered the Cassini spacecraft, a mission that came to an end in September 2017 when the probe ran out of fuel.

When Kepler launched, it had with 12 kilograms, or a little over 3 gallons of fuel onboard. The primary mission was planned to be three and a half years, with outside goal of operating the spacecraft for six years. Engineers said based on the amount of fuel that has been used over the course of its nine years in flight, they estimated that 2018 would be the year when the spacecraft’s fuel supplies would run out.

“We have been maintaining a close watch on the fuel estimates so that we can be prepared to bring the last batch of scientific data back to Earth and retire the spacecraft,” the team wrote.

Read more at Seeker

Environmental Change Forced Early Humans in East Africa to Innovate

Early stone-cutting tools called hand-axes (left) and later more sophisticated tools (right) designed to be attached to a shaft and potentially used as projectile weapons. Others were shaped as scrapers or awls. The National Museums of Kenya loaned the artifacts pictured above to conduct the analyses published in Science.
Stone Age tools were built to last, and many of their related technologies hold present day value. For example, the discovery around 320,000 years ago that obsidian, a type of glasslike volcanic rock, can produce ultra-sharp cutting edges is still a benefit today. Surgeons around the world often use obsidian scalpels, which are capable of cutting with greater precision than those made of steel.

Obsidian also revolutionized the creation of other tools, including weapons. The hefty hand-axes associated with the Acheulean industries, which began over a million years ago, were gradually replaced with lighter-weight, razor-edged triangular points that could be hafted to wood or bone and projected through the air.

"The world has never been the same since," Richard Potts, director of the National Museum of Natural History's human origins program, told Seeker. Potts has been leading the program's research in the Olorgesailie Basin of southern Kenya for 34 years in collaboration with the National Museums of Kenya.

In three new studies published in the journal Science, he and his colleagues report evidence from this region of not only major technological changes, like the usage of obsidian, but also environmental and ecological changes that were also taking place before and during the period when Homo sapiens emerged.

The changes coincide with the oldest known fossil record for our species in Africa, suggesting that the events were all driving forces in the evolution of Homo sapiens.

The findings counter a popular theory about human evolution, which holds that our species gradually changed in response to environmental pressures caused by expanding, arid grasslands in Africa. The so-called savanna hypothesis suggests that our ancestors transitioned from an arboreal to a bipedal lifestyle and evolved in other key ways due to living in this type of relatively stable environment.

Potts several years ago instead formulated a human evolution theory around "variability selection," which he explained "is a process linking adaptive change to large degrees of environment variability."

In the first of the three new studies, Potts and his team report that the Olorgesailie Basin — where hominids lived starting by at least 1.2 million years ago — was mostly floodplains until around 800,000 years ago. For the next several thousand years, an increasing pace of environmental change is seen in the geological record, such as through sediments and carbon isotopes of soil samples.

"The region went from being a stable system to one with significant tectonic activity, land-lake oscillations, fire-reddened zones, and intense wet-dry fluctuations," Potts said. "These would have resulted in unpredictable food and water supplies that, in turn, would have led to populations attempting to expand their geographical range in search of resources."

A bird's eye view of the Olorgesailie Basin in southern Kenya, which holds an archaeological record of early human life spanning more than a million years.
Some animals did not survive the period of instability. Many large-bodied grazing specialists, including some elephant and horse species, went extinct.

"I refer to them as the 'large lawn mowers' of the time,'" Potts said, adding that a baboon, a big hippo, a zebra, some large wild pigs, and other animals also went extinct following the environmental changes.

Absent those large creatures, related taxa with smaller body sizes emerged. The authors say this is another sign of climate variability.

As for hominids, they could no longer stay in one place for a long time, which was a problem because of their reliance on bulky stone tools for survival.

"What we see is the emergence of smaller and lighter tools, capable of easier transport," Potts said. "These gradually replaced the big, clunky Acheulean toolkit."

This technological shift, marking the beginning of the Middle Stone Age, was previously thought to have happened around 280,000 years ago. While hominid populations throughout much of Africa appear to have held on to their Acheulean tools until that time, those in East Africa made the transition by at least 320,000 years ago. At this time, about 42 percent of the more refined tools were crafted from obsidian.

Richard Potts surveys an assortment of Early Stone Age hand-axes discovered in the Olorgesailie Basin, Kenya.
The second study, led by anthropologist Alison Brooks of George Washington University's Center for the Advanced Study of Human Paleobiology, provides more detail on the human-made artifacts excavated from the Olorgesailie Basin.

She and her team surprisingly found that there is no local source there for obsidian, which means individuals must have traveled from around 16 to over 62 miles to obtain this coveted material. The shortest distance would have required scaling a mountain, Brooks said, making the trip all the more arduous.

"Other people were also living where the obsidian was, so the travelers could not just take and grab it," Brooks told Seeker. "Instead, the humans of the Olorgesailie Basin must have made distant contacts, with whom they might have engaged in trade."

"People at the time did not have money or animals to trade," she continued. "Friends were the real money in the bank."

Before around 320,000 years ago, these populations were not yet Homo sapiens, the researchers believe. It is likely that they were Homo heidelbergensis, a species of our genus that once lived in not only Africa but also in Europe and western Asia.

Fossils for Homo sapiens start to appear in Morocco around 315,000 years ago. A skull for Homo sapiens from Ethiopia dates to around 200,000 years ago, while a jawbone from our species excavated in Israel dates to about 180,000 years ago.

As more fossils are found, it is likely that more will date closer to 320,000 years ago, coinciding with the environmental and technological changes that were also occurring at this time. As Brooks indicated, social changes were occurring too, and there are clues for this in the fossil record.

Brooks and her team report the discovery of two lumps of ochre that had been manipulated by humans. It looks as though someone ground portions of the ochre, which would have produced a bright red powder.

"This powder could be mixed with anything — sweat, oil, water, fat — and produced a nice pigment," Brooks said.

Black and red rocks containing manganese and ocher were excavated at the Olorgesailie Basin, along with evidence that the rocks had been processed for use as coloring material.
The early humans also appear to have created black (manganese), brown, green, and white pigments, and perforated a piece of ochre on opposite sides in order to possibly wear or carry the colorful rock. By 77,000–80,000 years ago, there is evidence that humans were wearing beads with ochre on them. Neanderthals also appear to have used red ochre pigments by at least 250,000 years ago.

Early humans could have applied color to signify their social networks. Potts pointed out that this still occurs today with flags, tattoos, hats, university t-shirts, and other visual signs of affiliation.

"Placing color on skin, hair, and other parts of the body can be a symbolic behavior," Potts explained. "It can communicate, 'I'm part of a group that you know and you like us.'"

Conflicts occur among hunter-gatherers, but since smaller populations were spread over vast distances in Africa, the researchers believe that warfare during these earlier periods of human history would have been inherently kept in check.

This is not to say that the different hunter-gatherer groups did not have arguments. Spoken language cannot be preserved in the fossil record, save for evidence that a hominid possessed anatomy capable of speech. The researchers, however, suspect that the emergence of more complex social networks over longer distances and resulting symbolic behaviors would have advanced language evolution. 

Humans in Africa probably did not talk much about killing large animals for sustenance. With many big animal species extinct and replaced by smaller taxa, people appear to have relied more on small game.

Read more at Seeker

Mar 18, 2018

Marine ecologists study the effects of giant kelp on groups of organisms in the underwater forest ecosystem

When British naturalist Charles Darwin traveled to the Galapagos Islands in 1835, he took notice of the giant kelp forests ringing the islands. He believed that if those forests were destroyed, a significant number of species would be lost. These underwater ecosystems, Darwin believed, could be even more important than forests on land.

Since then, much scientific research has focused on the presence of giant kelp and the range of biodiversity it supports. Many marine biologists think of the world's biggest alga as the keystone species of its ecosystem, not only in terms of its structure -- a huge forestlike environment under the sea -- but also in terms of its tremendous productivity in supplying food for the near-shore ecosystem.

New analysis by UC Santa Barbara researchers has found that the kelp's structure may be more important than the food it provides. Using over a decade's worth of data from the Santa Barbara Coastal Long Term Ecological Research project, supported by the National Science Foundation, the investigators examined the effects of kelp on groups of organisms in the kelp forest ecosystem. Their results appear in the journal Proceedings of the Royal Society B.

"We posited that giant kelp fed herbivores in the system and provided structure and habitat for predators, and that it was fed upon by sea urchins and affected the understory communities of algae and sessile invertebrates in the kelp forest," said lead author Robert Miller, a research biologist in UCSB's Marine Science Institute (MSI). "We found that the giant kelp affected some of these groups more than others. Predator diversity was increased by it, but understory algae decreased as expected because the giant seaweed shades the bottom and prevents other algal species from doing well. In turn, giant kelp positively affected the sessile invertebrates -- sponges and sea squirts -- that live on the bottom but can often be outcompeted for space by algae."

The marine biologists built a structural equation model to examine the association between different variables all at once. This enabled them to hypothesize specific paths -- this type of modeling is also called path analysis -- and create a more powerful model.

The data showed that although sea urchins negatively affected giant kelp by grazing on it, no direct link between kelp and other herbivores existed. In reality, herbivores eat varied diets, which means they aren't necessarily affected when giant kelp abundance declines. In fact, the majority of kelp production is exported out of the forest rather than consumed by animals living there.

In other research, Miller and fellow MSI research biologist Mark Page used stable isotopes to determine that suspension-feeding sessile organisms subsist on phytoplankton rather than kelp detritus. This finding is contrary to the view held by many in the scientific community that kelp detritus is an important food source for these invertebrates.

"Our modeling results suggest that the physical aspects of the kelp -- its sheer size and its presence, the shade that it casts, its effect on flow and the habitat it provides for predators -- affect the reef ecosystem more than its productivity," Miller said. "Although kelp is clearly important as a food resource to some organisms on the reef, its structural effects are important and far reaching."

Apparently, Darwin was right.

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Space radiation more hazardous: Implication sfor astronauts and satellites

It might sound like something from a science fiction plot -- astronauts traveling into deep space being bombarded by cosmic rays -- but radiation exposure is science fact. As future missions look to travel back to the moon or even to Mars, new research from the University of New Hampshire's Space Science Center cautions that the exposure to radiation is much higher than previously thought and could have serious implications on both astronauts and satellite technology.

"The radiation dose rates from measurements obtained over the last four years exceeded trends from previous solar cycles by at least 30 percent, showing that the radiation environment is getting far more intense," said Nathan Schwadron, professor of physics and lead author of the study. "These particle radiation conditions present important environmental factors for space travel and space weather, and must be carefully studied and accounted for in the planning and design of future missions to the moon, Mars, asteroids and beyond."

In their study, recently published in the journal Space Weather, the researchers found that large fluxes in Galactic Cosmic Rays (GCR) are rising faster and are on path to exceed any other recorded time in the space age. They also point out that one of the most significant Solar Energetic Particle (SEP) events happened in September 2017 releasing large doses of radiation that could pose significant risk to both humans and satellites. Unshielded astronauts could experience acute effects like radiation sickness or more serious long-term health issues like cancer and organ damage, including to the heart, brain, and central nervous system.

In 2014, Schwadron and his team predicted around a 20 percent increase in radiation dose rates from one solar minimum to the next. Four years later, their newest research shows current conditions exceed their predictions by about 10 percent, showing the radiation environment is worsening even more than expected. "We now know that the radiation environment of deep space that we could send human crews into at this point is quite different compared to that of previous crewed missions to the moon," says Schwadron.

The authors used data from CRaTER on NASA's Lunar Reconnaissance Orbiter (LRO). Lunar observations (and other space-based observations) show that GCR radiation doses are rising faster than previously thought. Researchers point to the abnormally long period of the recent quieting of solar activity. In contrast, an active sun has frequent sunspots, which can intensify the sun's magnetic field. That magnetic field is then dragged out through the solar system by the solar wind and deflects galactic cosmic rays away from the solar system -- and from any astronauts in transit.

For most of the space age, the sun's activity ebbed and flowed like clockwork in 11-year cycles, with six- to eight-year lulls in activity, called solar minimum, followed by two- to three-year periods when the sun is more active. However, starting around 2006, scientists observed the longest solar minimum and weakest solar activity observed during the space age.

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