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The term anatomically modern humans (AMH) refers in paleoanthropology to individual members of the species Homo sapiens with an appearance consistent with the range of phenotypes in modern humans.
Anatomically modern humans evolved from archaic humans in the Middle Paleolithic, about 200,000 years ago. The emergence of anatomically modern human marks the dawn of the subspecies Homo sapiens sapiens, i.e. the subspecies of Homo sapiens to which all humans alive today belong. The oldest fossil remains of anatomically modern humans are the Omo remains found in modern-day East Africa, which date to 195,000 years ago and include two partial skulls as well as arm, leg, foot and pelvis bones.
Other fossils include the proposed Homo sapiens idaltu from Herto in Ethiopia that are almost 160,000 years old and the Skhul hominids from Israel, which are 90,000 years old.
The oldest human remains from which an entire genome has been extracted belongs to Ust’-Ishim man, who lived about 45,000 years ago in Western Siberia.
Behavioral modernity — a suite of changes in Homo sapiens behavior and cognition including abstract thinking, deep planning, symbolic behavior (e.g. art, ornamentation, music), exploitation of large game, and blade technology — is evident from around 40,000–50,000 years ago, and may have emerged abruptly then or may have arisen through gradual steps. However, it can and has been argued that Homo sapiens have been fully capable of modern behavior from the time they first evolved. Source: Anatomically modern human
Scientists have taken spectroscopic snapshots of nature’s most mysterious relay race: the passage of extra protons from one water molecule to another during conductivity. The finding represents a major benchmark in our knowledge of how water conducts a positive electrical charge, which is a fundamental mechanism found in biology and chemistry. The researchers, led by Yale chemistry professor Mark Johnson, report their discovery in the Dec. 1 edition of the journal Science.
For more than 200 years, scientists have speculated about the specific forces at work when electricity passes through water—a process known as the Grotthuss mechanism. It occurs in vision, for example, when light hits the eye’s retina. It also turns up in the way fuel cells operate.But the details have remained murky. In particular, scientists have sought an experimental way to follow the structural changes in the web of interconnected water molecules when an extra proton is transferred from one oxygen atom to another.
“The oxygen atoms don’t need to move much at all,” Johnson said. “It is kind of like Newton’s cradle, the child’s toy with a line of steel balls, each one suspended by a string. If you lift one ball so that it strikes the line, only the end ball moves away, leaving the others unperturbed.” Johnson’s lab has spent years exploring the chemistry of water at the molecular level. Often, this is done with specially designed instruments built at Yale. Among the lab’s many discoveries are innovative uses of electrospray ionization, which was developed by the late Yale Nobel laureate John Fenn.
Johnson and his team have developed ways to fast-freeze the chemical process so that transient structures can be isolated, revealing the contorted arrangements of atoms during a reaction. The practical uses for these methods range from the optimization of alternative energy technologies to the development of pharmaceuticals. In the case of the proton relay race, previous attempts to capture the process hinged on using infrared color changes to see it. But the result always came out looking like a blurry photograph.” In fact, it appeared that this blurring would be too severe to ever allow a compelling connection between color and structure,” Johnson said.
The answer, he found, was to work with only a few molecules of “heavy water”—water made of the deuterium isotope of hydrogen—and chill them to almost absolute zero. Suddenly, the images of the proton in motion were dramatically sharper.” In essence, we uncovered a kind of Rosetta Stone that reveals the structural information encoded in color,” Johnson said. “We were able to reveal a sequence of concerted deformations, like the frames of a movie.” Johnson’s lab was assisted by the experimental group of Knut Asmis at the University of Leipzig and the theory groups of Ken Jordan of the University of Pittsburgh and Anne McCoy of the University of Washington.
One area where this information will be useful is in understanding chemical processes that occur at the surface of water, Johnson noted. There is active debate among scientists regarding whether the surface of water is more or less acidic than the bulk of water. At present, there is no way to measure the surface pH of water. Source: A watershed moment in understanding how H2O conducts electricity
Any number can, in theory, be written as the product of prime numbers. For small numbers, this is easy (for example, the prime factors of 12 are 2, 2, and 3), but for large numbers, prime factorization becomes extremely difficult—so difficult that many of today’s cryptography algorithms rely on the complexity of the prime factorization of numbers with hundreds of digits to keep private information secure.
However, no one is exactly sure of just how difficult it is to decompose very large numbers into their prime factors. This question, called the factorization problem, is one of the biggest unsolved problems in computer science, despite the use of advanced mathematical and computer science strategies in attempts to solve it.
Now in a new study published in Physical Review Letters, researchers Jose Luis Rosales and Vicente Martin at the Technical University of Madrid have taken a different approach to the problem. The researchers have shown that the arithmetic used in factoring numbers into their prime factors can be translated into the physics of a device—a “quantum simulator”—that physically mimics the arithmetic rather than trying to directly calculate a solution like a computer does.
Although the researchers have not yet built a quantum simulator, they show that the prime factors of large numbers would correspond to the energy values of the simulator. Measuring the energy values would then give the solutions to a given factoring problem, suggesting that factoring large numbers into primes may not be as difficult as currently thought.
“The work opens a new avenue to factor numbers, but we do not yet know about its power,” Rosales told Phys.org. “It is very striking to find a completely new way to factor that comes directly from quantum physics. It does not demonstrate that factoring numbers is easy, but finding new ways to factor certainly does not add to the strength of algorithms based on its assumed complexity.” Source: Quantum physics offers new way to factor numbers
The speed of light in a vacuum, or c, is pretty much the most fundamental constant in physics – and according to the general theory of relativity, gravity travels at the same rate. But a new study suggests that the speed of light might not have always been this speed. In fact, in the early Universe, light might have outpaced gravity, and this new hypothesis could solve one of the biggest problems in physics.
Best of all, unlike a lot of hypotheses put forward in theoretical physics, this one can actually be tested, so we should be able to find out in the coming years if it’s true or not.
So what’s wrong with the speed of light and gravity in the first place? This conundrum comes from the earliest days of the Universe, and something called the horizon problem.
The horizon problem basically deals with the fact that the Universe reached a uniform temperature long before light particles (or photons) would have had time to reach all corners of the Universe.If the speed of light in a vacuum really is constant, and always has been, then how did the cosmos heat up so fast? Usually this problem is dealt with by the idea of inflation – which suggests that the Universe went through a huge period of expansion early on.
The hypothesis is that the temperature must have evened out when the Universe was all small and condensed, back when light didn’t have as far to travel, and then it rapidly grew. That makes sense – except no one knows why inflation started or stopped, and there’s no way of testing it.An alternative hypothesis has now been put forward by physicist Niayesh Ashfordi from the Perimeter Institute in Canada, and João Magueijo from Imperial College London.
Their idea is this: in the earliest days of the Universe, light and gravity travelled at different speeds. This could mean that light used to travel faster than it does now, or gravity might have travelled slower. Either way, “if photons moved faster than gravity just after the Big Bang, that would have let them get far enough for the Universe to reach an equilibrium temperature much more quickly,” the researchers told Michael Brooks over at New Scientist.
For now, this is just an hypothesis. But the really exciting part is that it can actually be tested. If the hypothesis is true, there will be a particular signature left in the cosmic microwave background radiation – the leftover radiation from the Big Bang that we can still detect and study today.
The PowerWatch is a rugged aircraft-grade aluminium smartwatch that wirelessly syncs with your smartphone, automatically adjusting to current time zones and has changeable watch faces. The watch is also water resistant to 50m so is perfect for swimming.
PowerWatch measures calories burned, activity level and sleep using advanced thermoelectric technology. It’s also the only watch to feature a power meter which displays how much electrical power you are generating. The thermoelectric technology behind the watch converts heat to electric power. Based on the Seebeck effect discovered in 1821, in the absence of an applied voltage gradient, electric current can still be generated if there is a temperature gradient. NASA has used similar technology to power the Voyager spacecraft and Curiosity, the mars rover.
You never need to recharge the watch; when it’s taken off, your data is stored in memory and it effectively goes to sleep. Put it back on and the watch comes to life right where you left it. Source: – The world’s first smartwatch powered by body heat
Just as a boat can be driven off course by a log in its path, a single, random mutation can send life in a new direction. That scenario, says University of Oregon biochemist Ken Prehoda, illustrates how a random mutation sparked a huge jump in the evolutionary course of a protein important for the evolution of animals.In January, Prehoda was on a team that found that a random mutation 600 million years ago in a single-celled organism created a new family of proteins that are important for multicellular life. In a new paper, Prehoda and colleagues describe what the mutation did to the original protein, an enzyme known as guanylate kinase.
The paper, now online, will be featured with an illustration on the cover of the Nov. 23 issue of the Journal of the American Chemical Society.
Mutations happen randomly. Most are bad news. Understanding them better, Prehoda said, could potentially point to new treatments for human diseases such as cancer. Occasionally a mutation is good, helping an organism adapt to environmental changes or advancing overall fitness.
Prehoda’s lab initially used a molecular technique called ancestral protein reconstruction. The technique allows researchers to move backward in the evolutionary tree to see molecular changes and infer how proteins performed in the past.For the new study, Prehoda’s lab collaborated with researchers at the Medical College of Wisconsin who studied whether the mutation they had discovered had possibly changed the flexibility of the protein. Next, his team turned to computer simulations in the UO’s High Performance Computing Research Core Facility to explore how the altered flexibility they isolated, in turn, led to changes in the protein’s interactions.
“We found that this mutation that helped our unicellular ancestor to become multicellular, and ended up leading to an entirely new family of proteins that are specific to animals, did so in a very interesting way,” said Prehoda, who is the director of the UO’s Institute of Molecular Biology. “Amazingly, this one mutation took a protein that was really flexible—an important trait for its old job—and made it much more rigid so it could advance to a new function.”
The mutation, which researchers labeled s36P, set off a cascade of events in which guanylate kinase interactions took new routes and evolved into more complex multicellular organisms, Prehoda said. The mutation is still conserved in all animals today, he added.
“A lot of the proteins that do the work in our bodies can be thought of as molecular machines,” Prehoda said. “They move in a way that is coordinated with function. Each protein spins in a circle or motors along filaments. Our protein, before the mutation, was an enzyme that had certain flexible movements related to its function. This one mutation fixed the protein’s backbone, locking the molecule into a shape that is important for its new function.”
Prehoda and colleagues reported their discovery of mutation in a paper that appeared Jan. 7 in the journal eLife. Source: Mutation that triggered multicellular life altered protein flexibility
Astronomers claim to have discovered the roundest object ever measured in nature.Kepler 11145123 is a distant, slowly rotating star that’s more than twice the size of the Sun .Researchers were able to show that the difference between its radius as measured to the equator and the radius measured to the poles was just 3km. “This makes Kepler 11145123 the roundest natural object ever measured,” said lead author Prof Laurent Gizon. He added that it was “even more round than the Sun”.
Prof Gizon, from the Max Planck Institute for Solar System Research (MPS), and his colleagues used a technique called asteroseismology – the study of how stars pulsate, or oscillate.Nasa’s Kepler space telescope observed the star’s oscillations continuously for more than four years. The periodic expansions and contractions of Kepler 11145123 can be gleaned from fluctuations in its brightness. And from these data, astronomers were able to extract information about its shape
.Using the method, Prof Gizon and his colleagues discovered that the star rotated faster at the surface than in the core, contributing to an unexpected rounding of its form. The difference of 3km, between the polar and equatorial radii, is tiny compared to the star’s mean radius of 1.5 million km.
The authors say that this distortion is probably caused by factors other than rotation alone. They suggest that a weak magnetic field surrounds the star, making the star appear even more rounded.The research is published in the journal Science Advances.
Thanks to Phil Krause for suggesting this post.
The Astonishing Hypothesis is a 1994 book by scientist Francis Crick about consciousness. Crick, one of the co-discoverers of the molecular structure of DNA, later became a theorist for neurobiology and the study of the brain. The Astonishing Hypothesis is mostly concerned with establishing a basis for scientific study of consciousness; however, Crick places the study of consciousness within a larger social context. Human consciousness according to Crick is central to human existence and so scientists find themselves approaching topics traditionally left to philosophy and religion.
The Astonishing Hypothesis posits that “a person’s mental activities are entirely due to the behavior of nerve cells, glial cells, and the atoms, ions, and molecules that make them up and influence them.” Crick claims that scientific study of the brain during the 20th century led to acceptance of consciousness, free will, and the human soul as subjects for scientific investigation.
Rather than attempting to cover all the aspects of consciousness (self-awareness, thought, imagination, perception, etc.), Crick focuses on the primate visual system and breaks down the prerequisites for conscious experience into several broad subconditons, including some sort of short term memory and attention mechanism. The book then delves into a brief overview of many neuroscientific topics, ranging from a survey of how neurons function to a description of basic neural circuits and their artificial equivalents. Throughout, Crick cites various experiments which illustrate the narrow points he is making about visual awareness, such as studies investigating the phenomenon of blindsight in macaques.
The later chapters of the book try to synthesize many of the points made earlier about the visual system into a unified framework, although Crick frequently notes the many exceptions to his assumptions and the clumsiness of many of his attempts at synthesis. Also, here he takes the opportunity to make suggestions for further experiments that could provide empirical basis for further understanding about human consciousness and includes a brief addendum on several topics he purposefully glossed over, like free will. Overall, the message Crick repeats as the main purpose of writing the Astonishing Hypothesis is to break the scientific community’s reluctance to give consciousness a thorough and scientifically-grounded investigation, and to encourage others such as philosophers to address the issues of consciousness in a way that takes account of neuroscientific discoveries.
For background and criticism: The Astonishing Hypothesis
In the late 1880s, the American expatriate John Singer Sargent experimented with portrait compositions whose informality and naturalness stood in sharp contrast to his commissioned studio portraits of elegant society types. Inspired in part by the Impressionist works of his friend Claude Monet, this portrait depicts another French artist friend, Paul Helleu, and his young wife, Alice, at Fladbury, in England’s Cotswolds. Liberated from pictorial conventions, Sargent here featured the compositional asymmetry, natural light, and casual inattention of his “sitters.”
A strange and beautiful sight greeted locals in the Gulf of Ob, in northwest Siberia, after thousands of natural snowballs formed on the beach. An 11-mile (18km) stretch of coast was covered in the icy spheres.
The sculptural shapes range from the size of a tennis ball to almost 1m (3ft) across. They result from a rare environmental process where small pieces of ice form, are rolled by wind and water, and end up as giant snowballs. Locals in the village of Nyda, which lies on the Yamal Peninsula just above the Arctic Circle, say they have never seen anything to compare to them. Source: BBC News
Imagine spending your whole life seeing the world in black and white, and then seeing a vase of roses in full color for the first time. That’s kind of what it was like for the scientists who have taken the first multicolor images of cells using an electron microscope.
Electron microscopes can magnify an object up to 10 million times, allowing researchers to peer into the inner workings of, say, a cell or a fly’s eye, but until now they’ve only been able to see in black and white. The new advance—15 years in the making—uses three different kinds of rare earth metals called lanthanides (think top row of that extra block below the periodic table) layered one-by-one over cells on a microscope slide.
The microscope detects when each metal loses electrons and records each unique loss as an artificial color. So far, the researchers can only produce three colors—red, green, and yellow, they report online today in Cell Chemical Biology. Still, the ability to use color creates stark contrasts that grayscale images simply can’t accomplish. The team could see a string of proteins squeezing through a cell membrane (pictured) in more detail than scientists ever had before, for example. With a few more tweaks and added metal ions, researchers hope to add three or four other colors to the mix and improve the images’ resolution. Source: See the first color images produced by an electron microscope