Jul 5, 2015
The study, published in Cell Reports on July 2, sheds light on the evolutionary biology of these extinct giants.
"This is by far the most comprehensive study to look at the genetic changes that make a woolly mammoth a woolly mammoth," said study author Vincent Lynch, PhD, assistant professor of human genetics at the University of Chicago. "They are an excellent model to understand how morphological evolution works, because mammoths are so closely related to living elephants, which have none of the traits they had."
Woolly mammoths last roamed the frigid tundra steppes of northern Asia, Europe and North America roughly 10,000 years ago. Well-studied due to the abundance of skeletons, frozen carcasses and depictions in prehistoric art, woolly mammoths possessed long, coarse fur, a thick layer of subcutaneous fat, small ears and tails and a brown-fat deposit behind the neck which may have functioned similar to a camel hump. Previous efforts to sequence preserved mammoth DNA were error-prone or yielded insights into only a limited number of genes.
To thoroughly characterize mammoth-specific genes and their functions, Lynch and his colleagues deep sequenced the genomes of two woolly mammoths and three Asian elephants -- the closest living relative of the mammoth. They then compared these genomes against each other and against the genome of African elephants, a slightly more distant evolutionary cousin to both mammoths and Asian elephants.
The team identified roughly 1.4 million genetic variants unique to woolly mammoths. These caused changes to the proteins produced by around 1,600 genes, including 26 that lost function and one that was duplicated. To infer the functional effects of these differences, they ran multiple computational analyses, including comparisons to massive databases of known gene functions and of mice in which genes are artificially deactivated.
Genes with mammoth-specific changes were most strongly linked to fat metabolism (including brown fat regulation), insulin signaling, skin and hair development (including genes associated with lighter hair color), temperature sensation and circadian clock biology -- all of which would have been important for adapting to the extreme cold and dramatic seasonal variations in day length in the Arctic. The team also identified genes associated with the mammoth body plan, such as skull shape, small ears and short tails.
Of particular interest was the group of genes responsible for temperature sensation, which also play roles in hair growth and fat storage. The team used ancestral sequence reconstruction techniques to "resurrect" the mammoth version of one of these genes, TRPV3. When transplanted into human cells in the laboratory, the mammoth TRPV3 gene produced a protein that is less responsive to heat than an ancestral elephant version of the gene. This result is supported by observations in mice that have TRPV3 artificially silenced. These mice prefer colder environments than normal mice and have wavier hair.
Although the functions of these genes match well with the environment in which woolly mammoths were known to live, Lynch warns that it is not direct proof of their effects in live mammoths. The regulation of gene expression, for example, is extremely difficult to study through the genome alone.
"We can't know with absolute certainty the effects of these genes unless someone resurrects a complete woolly mammoth, but we can try to infer by doing experiments in the laboratory," he said. Lynch and his colleagues are now identifying candidates for other mammoth genes to functionally test as well as planning experiments to study mammoth proteins in elephant cells.
Read more at Science Daily
Ground control teams lost radio contact with New Horizons for about 80 minutes on Saturday when the spacecraft put itself in an automated safe mode after it switched over from its primary to its backup computer. What triggered the computer switch is under investigation.
With New Horizons about 3 billion miles from Earth, radio signals traveling at the speed of light take about 4.5 hours to arrive and another 4.5 hours to get the spacecraft’s return messages.
“Full recovery is expected to take from one to several days,” NASA wrote in a status report on Saturday. “New Horizons will be temporarily unable to collect science data during that time.”
On Sunday, ground controllers planned to relay a final batch of instructions to New Horizons to prepare for its July 14 flyby of Pluto, the only major body in the solar system that has not yet been visited by a robotic spacecraft.
The “encounter program” includes software to prohibit the very type of automated safe mode that New Horizons executed Saturday afternoon.
“Encounter mode short-circuits the on board intelligent autopilot so that if something goes wrong, instead of calling home for help, which is what most spacecraft do and what New Horizons does during cruise flight, it will just stay on the timeline. It will try to fix the problem, but it will rejoin the timeline because if it ‘went fetal,’ as we say, if it just called home for help, it could miss the flyby,” New Horizons lead scientist Alan Stern told Discovery News before Saturday’s problem.
Read more at Discovery News
Jul 4, 2015
Common spiders are frequently observed to fly using a technique called 'ballooning'. This involves using their silk to catch the wind which then lifts them up into the air. Ballooning spiders are estimated to move up to 30 km per day when wind conditions are suitable, helping in their quest for new habitats and resources.
This dispersal strategy, however, involves a significant risk. The airborne spider has little control over where it travels and could end up landing on water, which has been thought to be unsuitable for its survival.
Lead author Morito Hayashi from the Natural History Museum, London, UK, said: "Even Darwin took note of flying spiders that kept dropping on the Beagle miles away from the sea shore. But given that spiders are terrestrial, and that they do not have control over where they will travel when ballooning, how could evolution allow such risky behavior to be maintained?"
"We've now found that spiders actively adopt postures that allow them to use the wind direction to control their journey on water. They even drop silk and stop on the water surface when they want. This ability compensates for the risks of landing on water after the uncontrolled spider flights."
The researchers collected 325 adult spiders belonging to 21 common species from small islands in nature reserves in Nottinghamshire, UK. The spiders' behavior was observed on trays of water in reaction to pump-generated air, and this was compared to their reactions on dry surfaces.
Many of the spider species adopted elaborate postures, such as lifting up a pair of legs, to seemingly take advantage of the wind current whilst on the water surface. This allowed them to 'sail' in turbulent, still, fresh, and salt water conditions.
By releasing silk on water, the sailing spiders also seemed to act like ships dropping their anchors to slow down or stop their movement. This suggests that the silk may sometimes work as a dragline for the water-trapped spider to attach to floating objects or to the shore. These behavioral adaptations could allow spiders to survive encounters with aquatic environments.
The research team also found that the spiders that adopted 'ballooning' behavior for airborne dispersal were also the most eager and able 'sailors'. The association between the two behaviors may indicate the importance of ballooners also being able to sail, which could be invaluable when landing on water.
Read more at Science Daily
On a basic-science front, the findings, which appear in the July 3 issue of the journal Science, provide a long-sought answer to why some landscape features appear so orderly, with distinct and evenly spaced valleys and ridges.
Picture the Painted Hills near John Day, Oregon, the Colorado Plateau, the badlands of Montana and South Dakota, and even portions of the Coastal Range between Eugene and Florence, Oregon. These watersheds are masterpieces that nature has formed over geological timescales, said the UO's Joshua J. Roering.
The regularity of hill and valley landforms, he said, is reached after a long tug-of-war between erosion driven by runoff, which influences how rivers cut their paths in valley floors, and soil movement on hillsides caused by disturbances from such things as burrowing gophers, tree roots, digging ants and frost.
The National Science Foundation-funded project (EAR 1252177) is part of a growing effort in geomorphology -- the study of the origin and evolution of many landscape features -- to understand how soil processes at work on hillsides compete with water runoff in the formation of valley floors.
Put simply, runoff processes carve valleys while soil movement on hill slopes tends to fill them. The relative vigor of these competing forces determines the spacing of hills and valleys and the degree of drainage dissection. "Hill-slope processes help determine valley density and the way valleys and ridges form," Roering said. "These networks are climate dependent."
Over the course of five 20-hour experiments conducted in small sandboxes, UO doctoral student Kristin E. Sweeney, the study's lead author, extruded crystalline silica to represent uplift due to tectonic forces. To induce erosion, she used mist from 42 nozzles to create precipitation-driven runoff and 625 blunt needles that fired periodic bursts of large water drops to mimic natural disturbances that occur on hill slopes. Each experiment showed how the processes, acting together, converted flat plains into ridges and valleys.
"In our experiments we were able to dictate the processes involved and observe the landscapes that arise," Sweeney said. "We were able to directly control the various processes. Previous research has only attempted to replicate channel processes -- what the rivers do. We essentially started from scratch, working to see the movement of sediment slopes in a realistic way.
"Ridges and valleys are part of a fundamental landscape pattern that people easily recognize," she said. "From an airplane, you look down and you see watersheds, you see valleys, and they tend to have very regular spacing. Explaining this pattern is a fundamental question in geomorphology."
The study's three-member team also included Christopher Ellis, senior research associate at the University of Minnesota's St. Anthony Falls Laboratory where the experiments were conducted. The team spent more than a year developing a workable methodology to study the sediment transfer processes.
Read more at Science Daily
Jul 3, 2015
"Almost all animal tails have circular or oval cross-sections--but not the seahorse's. We wondered why," said Michael Porter, an assistant professor in mechanical engineering at Clemson University and the lead investigator on the study, who earned his Ph.D. in materials science and engineering at the University of California, San Diego, in 2014. "We found that the squared-shaped tails are better when both grasping and armor are needed."
Also remarkable, the square plates make the seahorse's tail stiffer, stronger and more resistant to strain at the same time. Usually, strengthening any one of these characteristics will weaken at least one of the others, Porter said. He and colleagues set out to find out why.
They found that square plates move with only one degree of freedom when crushed: they slide. By contrast, circular plates have two degrees of freedom: they slide and they rotate. As a result, the square plates absorb much more energy before permanent failure begins.
To arrive at their findings, researchers used a wide range of techniques, including 3D-printing a simplified model of the seahorse's tail, which they then bent, twisted, compressed and crushed. They also 3D-printed and ran similar experiments on a tail model made of overlapping round segments that they designed and that is not found in nature.
"New technologies, like 3D-printing, allow us to mimic biological designs, but also build hypothetical models of designs not found in nature," said Porter "We can then test them against each other to find inspiration for new engineering applications and also explain why biological systems may have evolved."
The Science study builds on work Porter started at UC San Diego in collaboration with Dominique Adriaens, professor of evolutionary biology at Ghent University and UC San Diego materials science and engineering professors Joanna McKittrick and Marc Meyers. "Michael decided to use engineering and technology to explain biological features," said McKittrick, who was Porter's co-advisor and is a co-author on the paper. You can simplify nature and study it in the lab, added Meyers, also a co-author and Porter co-advisor. "Then you can build new bioinspired structures and devices."
Porter's research group at Clemson is now applying this method to develop new structures and robotic systems that mimic a variety of other natural--and hypothetical--systems, allowing him to translate his research across disciplines: from biology as a source of inspiration for engineering; and from engineering as a tool for the exploration of biology.
When researchers twisted the 3D-printed square seahorse tail model, they found that its plates interfered with one another, limiting its range of movement by about half when compared to the model made of round segments. In addition, after it was twisted, the square model returned to its original shape faster, while expending a minimum amount of energy. Researchers theorize this might protect the tail from damage. By contrast, a tail made from round segments twists easily and requires more energy to return to its original shape. Researchers also found that the tail's square segments created more contact points with the surface that it is gripping when compared to a tail with round segments.
In addition, a seahorse's tail bends in a way that allows it to grasp objects within its line of sight. Study co-author Ross L. Hatton, assistant professor of mechanical engineering at Oregon State University and specialist in robotics, helped Porter develop geometric models describing the tail's mechanics and proving its geometry is optimized precisely for this kind of grasping.
Researchers also compressed the models made of 3D-printed segments and compared their behavior to 3D-printed solid structures with square and circular cross-sections--but without segments. They found that a seahorse's tail has joints at the exact locations where the solid structures fail when crushed. This allows the structures to absorb more energy on impact. Even more impressive, the square model outperformed the round one in all crushing tests. This is because square segments fail without changing their general shape. By contrast, round segments open up under the applied load, changing their shape from circular to elliptical.
This is important, because water birds are one of the seahorse's main predators and capture their prey with their beaks and crush them in the process.
Porter is also investigating how devices inspired by the structure of the seahorse's tail could be used in real life. One possibility is to scale up the structure to build a gripping robotic arm that can be used in hostile environments. Another is to scale it down to build a catheter. But the possibilities are many, said study co-author Meyers.
Read more at Science Daily
The ancient monkey, known scientifically as Victoriapithecus, first made headlines in 1997 when its fossilized skull was discovered on an island in Kenya's Lake Victoria, where it lived 15 million years ago.
Now, thanks to high-resolution X-ray imaging, researchers have peered inside its cranial cavity and created a three-dimensional computer model of what the animal's brain likely looked like.
Micro-CT scans of the creature's skull show that Victoriapithecus had a tiny brain relative to its body.
Co-authors Fred Spoor of the Max Planck Institute for Evolutionary Anthropology and Lauren Gonzales of Duke University calculated its brain volume to be about 36 cubic centimeters, which is less than half the volume of monkeys of the same body size living today.
If similar-sized monkeys have brains the size of oranges, the brain of this particular male was more akin to a plum.
"When Lauren finished analyzing the scans she called me and said, 'You won't believe what the brain looks like,'" said co-author Brenda Benefit of New Mexico State University, who first discovered the skull with NMSU co-author Monte McCrossin.
Despite its puny proportions, the animal's brain was surprisingly complex.
The CT scans revealed numerous distinctive wrinkles and folds, and the olfactory bulb -- the part of the brain used to perceive and analyze smells -- was three times larger than expected.
"It probably had a better sense of smell than many monkeys and apes living today," Gonzales said. "In living higher primates you find the opposite: the brain is very big, and the olfactory bulb is very small, presumably because as their vision got better their sense of smell got worse."
"But instead of a tradeoff between smell and sight, Victoriapithecus might have retained both capabilities," Gonzales said.
The findings, published in the July 3 issue of Nature Communications, are important because they offer new clues to how primate brains changed over time, and during a period from which there are very few fossils.
"This is the oldest skull researchers have found for Old World monkeys, so it's one of the only clues we have to their early brain evolution," Benefit said.
In the absence of fossil evidence, previous researchers have disagreed over whether primate brains got bigger first, and then more folded and complex, or vice versa.
"In the part of the primate family tree that includes apes and humans, the thinking is that brains got bigger and then they get more folded and complex," Gonzales said. "But this study is some of the hardest proof that in monkeys, the order of events was reversed -- complexity came first and bigger brains came later."
Read more at Science Daily
The argument is one of several that emerge from The Runes Of Evolution, a new book in which the leading evolutionary biologist, Professor Simon Conway Morris, makes the case for a ubiquitous "map of life" that governs the way in which all living things develop.
It builds on the established principle of convergent evolution, a widely-supported theory -- although one still disputed by some biologists -- that different species will independently evolve similar features.
Conway Morris argues that convergence is not just common, but everywhere, and that it has governed every aspect of life's development on Earth. Proteins, eyes, limbs, intelligence, tool-making -- even our capacity to experience orgasms -- are, he argues, inevitable once life emerges.
The book claims that evolution is therefore far from random, but a predictable process that operates according to a fairly rigid set of rules.
If that is the case, then it follows that life similar to that on Earth would also develop in the right conditions on other, equivalent planets. Given the growing number of Earth-like planets of which astronomers are now aware, it is increasingly extraordinary that aliens that look and behave something like us have not been found, he suggests.
"Convergence is one of the best arguments for Darwinian adaptation, but its sheer ubiquity has not been appreciated," Professor Conway Morris, who is a Fellow at St John's College, University of Cambridge, said.
"Often, research into convergence is accompanied by exclamations of surprise, describing it as uncanny, remarkable and astonishing. In fact it is everywhere, and that is a remarkable indication that evolution is far from a random process. And if the outcomes of evolution are at least broadly predictable, then what applies on Earth will apply across the Milky Way, and beyond."
Professor Conway Morris has previously raised the prospect that alien life, if out there, would resemble earthlings -- with limbs, heads, and bodies -- notably at a Royal Society Conference in London in 2010. His new book goes even further, however, adding that any Earth-like planet should also evolve thunniform predators (like sharks), pitcher plants, mangroves, and mushrooms, among many other things.
Limbs, brains and intelligence would, similarly, be "almost guaranteed." The traits of human-like intelligence have evolved in other species -- the octopus and some birds, for example, both exhibit social playfulness -- and this, the book suggests, indicates that intelligence is an inevitable consequence of evolution that would characterise extraterrestrials as well.
Underpinning this is Conway Morris' claim that convergence is demonstrable at every major stepping stone in evolutionary history, from early cells, through to the emergence of tissues, sensory systems, limbs, and the ability to make and use tools.
The theory, in essence, is that different species will evolve similar solutions to problems via different paths. A commonly-cited example is the octopus, which has evolved a camera eye that is closely similar to that of humans, although distinctive in important ways that reflect its own history. Although octopi and humans have a common ancestor, possibly a slug-like creature, this lived 550 million years ago and lacked numerous complex features that the two now share. The camera eye of each must therefore have evolved independently.
Conway Morris argues that this process provides an underlying evolutionary framework that defines all life, and leads to innumerable surprises in the natural world. The book cites examples such as collagen, the protein found in connective tissue, which has emerged independently in both fungi and bacteria; or the fact that fruit flies seem to get drunk in the same manner as humans. So too the capacity for disgust in humans -- a hard-wired instinct helping us avoid infection and disease -- is also exhibited by leaf-cutter ants.
The study also identifies many less obvious evolutionary "analogues," where species have evolved certain properties and characteristics that do not appear to be alike, but are actually very similar. For example, "woodpeckerlike habits" are seen in lemurs and extinct marsupials, while the mechanics of an octopus' tentacles are far closer to those of a human arm than we might expect, and even their suckers can operate rather like hands.
Conway Morris contends that all life navigates across this evolutionary map, the basis of what he describes as a "predictive biology." "Biology travels through history," he writes, "but ends up at much the same destination."
This, however, raises fascinating and problematic questions about the possibility of life occurring on other planets. "The number of Earth-like planets seems to be far greater than was thought possible even a few years ago," Conway Morris said. "That doesn't necessarily mean that they have life, because we don't necessarily understand how life originates. The consensus offered by convergence, however, is that life is going to evolve wherever it can."
"I would argue that in any habitable zone that doesn't boil or freeze, intelligent life is going to emerge, because intelligence is convergent. One can say with reasonable confidence that the likelihood of something analogous to a human evolving is really pretty high. And given the number of potential planets that we now have good reason to think exist, even if the dice only come up the right way every one in 100 throws, that still leads to a very large number of intelligences scattered around, that are likely to be similar to us."
If this is so, as the book suggests in its introduction, then it makes Enrico Fermi's famous paradox -- why, if aliens exist, we have not yet been contacted -- even more perplexing. "The almost-certainty of ET being out there means that something does not add up, and badly," Conway Morris said. "We should not be alone, but we are."
Read more at Science Daily
|This is the business end of the tarantula wasp, and by business end I mean the end that once made a guy crawl into a ditch and cry. True story.|
Joining the bullet ant at four is a critter that lives right here in the southwestern US: the tarantula hawk. It’s actually a kind of solitary wasp with a sting whose resulting pain only lasts three seconds, but it’s so fiercely electric that could only be described as totally unacceptable. “There are some vivid descriptions of people getting stung by these things,” says invertebrate biologist Ben Hutchins of Texas Parks and Wildlife, “and their recommendation—and this was actually in a peer-reviewed journal—was to just lie down and start screaming, because few if any people could maintain verbal and physical coordination after getting stung by one of these things. You’re likely to just run off and hurt yourself. So just lie down and start yelling.”
|Either this wasp is giant or this is a child holding it. Probably the former though, on account of child endangerment.|
Which is why folks in Texas have seemed a bit…worried over the past few weeks, as numbers of the things are on the rise. In reality, though, there’s nothing to be worried about here (trust me). The tarantula hawk is in fact a brilliant parasite that attacks tarantulas, not humans, paralyzing them with a sting before dragging them into a den. Here it lays an egg that hatches into a larva and devours the paralyzed spider alive—over the course of several weeks.
|A tarantula wasp faces off against its namesake victim: the hawk.|
Accordingly, there’s not much to stop them when their numbers start climbing, like they are right now in Texas. Thanks to a strong rainy season, vegetation is doing quite well, and when vegetation does quite well, so do insects. The tarantula hawk is actually a nectar-feeder, not a carnivore, so it’s in fat city these days.
But not all of these wasps sting: The males can’t do it at all. This is because stingers in the insect world belong to the females (the structures evolved from ovipositors, which the females use to lay eggs). So in lovely conditions such as these, males will hang out on flowers and wait for the females to come around and mate. The female then flies off—and this is where the real fun begins.
Except for the tarantulas. They’re not going to like this one bit.
Unlike a lot of insects, the fertilized female won’t just be depositing her eggs somewhere and flying off, hoping they’ll survive on their own. Nope, she finds an unwitting caretaker first: specifically, any number of tarantulas that are also good and active during these times of plenty.
The she-wasp has to be careful, because while she’s pretty darn big, the tarantula can be several times bigger than her. And although tarantulas may be harmless to humans, they have massive fangs that could do a number on the wasp. “The tarantula hawk will kind of approach the tarantula,” says Hutchins, “back away, approach, and then go in and actually get in underneath the tarantula and then flip it over, and then sting it. She’s usually looking for a chink in the tarantula’s armor, and that’s often at the joints in the legs.”
And she’s really good at it. One survey found that in 400 battles, only a single wasp perished. But that isn’t to say the tarantulas weren’t putting up a good fight. In his sneakily comic scientific paper, Schmidt notes that researchers have reported “violent encounters, often hearing loud crunching or snapping sounds as the spider has the wasp in its jaws, and with spiders frequently losing legs during the encounters.” It seems that the tarantula hawks’ hard, smooth exoskeletons may crunch a bit, but they still save their owners from death.
|The wasp drags its victim to its doom. Not the wasp’s doom. The spider’s. Boy I’m on a roll this week.|
That there is one hell of a head start in life for the kiddo. It’s a striking contrast to the lives of social wasps, which collectively care for their young without encouraging them to devour paralyzed tarantulas. And indeed, this manifests in the wasps’ venom itself. Typically, the venom of social wasps tends to be both painful and damaging to tissue, whereas the tarantula hawk’s is all agony and no damage. This is likely because social wasps have a queen and young to protect from their enemies, so simply inflicting pain may not do the trick—the target may be down, but not out. In contrast, the tarantula hawk is a lone wolf, looking out only for itself. All it has to do is stun its attacker and make a getaway.
Read more at Wired Science
Jul 2, 2015
Commonly known as “Villa Domitia,” the imperial complex stood magnificently 2,000 years ago on the island of Giannutri, a rocky crescent about 3 miles long with thick areas of Mediterranean vegetation.
"The villa was built on a harsh, uninhabited site, "Paola Rendini, of the archaeological superintendency of Tuscany, told Discovery News. "There is no water spring on the island, and raw materials had to be carried from the mainland. It was a huge task,"
Despite such difficulties, the Romans managed to shape up a sprawling "otium" (leisure) villa, lavishly decorated with precious marbles, mosaics and frescoes.
The majestic complex marks Giannutri’s most glorious time. Today the southernmost island of the Tuscan archipelago is almost empty -- populated by a huge colony of seagulls and, in summer, by a group of villa owners who rely on rain water and water shipped from the mainland.
The island has a complex recent history, marked by legal and administrative issues. A number of authorities coexist on this piece of land which is fewer than 4 square miles in size.
Part of the Tuscan Archipelago National Park, the island belongs to the municipality of Giglio island and is largely privately owned, apart from some areas owned by Italy’s Ministry of the Environment. The Villa Domitia and its annexes are under the control of Italy’s Ministry of Cultural Heritage.
Although the villa has been the focus of several restoration and conservation campaigns since 1989, overlapping regulations have basically prevented its opening to the public, slowing procedures and interventions.
"Finally, this jewel can be seen. We are very proud of this reopening," Sergio Ortelli, the mayor of Giglio and Giannutri islands, told Discovery News.
A year after the removal of the Costa Concordia shipwreck, Giglio is struggling to restore its well deserved reputation of unspoiled island rich in food, wine, traditions and history.
"The opening in Giannutri goes in this direction. In hard times, focusing on culture always pays off," Ortelli said.
Today the ruins represent a bright yet fragmented evidence of the once sumptuous villa, showing impressive flights of steps, granite columns, intricately-sculpted capitals, pieces of precious marbles and long stretches of thick walls in opus reticulatum (small squared stones laid diagonally to form a net-like pattern).
Spreading for about 10 acres, the villa was built on different terraces on a property which most likely belonged to the prominent Domitii Ahenobarbi, Nero’s family.
Brick stamps recovered at the site attest to three major building phases: the first dates to the end of the first century A.D., in the late Flavian period (A.D. 69–96), another to the early second century A.D. and the third to the reign of Hadrian.
"Giannutri was the first island after Ostia, the port of Rome, thus relatively easy to reach. The villa was likely used by the emperors Domitian, Trajan and Hadrian," Rendini said.
Rendini, who has been working on the site since 1981, noted Villa Domitia represents one of the most intelligible evidences of a leisure imperial residence, fully equipped with all comforts.
Relying on large cisterns, a sophisticated system collected rainwater and solved the problem of the lack of springs on the island. Indeed, those cisterns are still in use today to provide water on Giannutri.
An underfloor heating system allowed a pleasant winter stay at the villa, which was also equipped with thermal baths.
The complex had two well protected harbors, one on Cala Spalmatoio on the eastern coast, and the other at Cala Maestra, on the western side. Near this harbor, remains of a structure for the production of salted fish have been found.
The residential quarter, which included the bedrooms and a large room with stunning views over the sea, spread on three terraces around an open courtyard. This featured a rectangular basin for collecting rainwater, surrounded by six imposing granite columns boasting intricately carved Corinthian capitals.
On a much higher level, toward east, are the remains of the slave quarters.
Only partially excavated, the villa was first brought to light in the 1920-1930 by Bice Vaccarino, a woman who had rented the island, in collaboration with archaeologist Doro Levi.
"In 1928 a great marble flight of steps that goes down to the sea first emerged, revealing the importance and the (wealth) of the villa," the journal Emporium wrote in 1931.
Reporting on Vaccarino's archaeological efforts, the account described newly unearthed rooms with polychrome marbles and geometrical patterns and impressive mosaics such as one showing a marine scene with two dolphins.
Read more at Discovery News
The discovery, reported in the latest issue of the journal Nature, documents the first known case of sex reversal in the wild for a reptile.
“Sex reversal occurs when the genetic sex of an individual, usually represented by sex chromosomes, is reversed to the other sex,” senior author Arthur Georges explained to Discovery News. “An example would be in humans, where an XY individual, normally a boy, develops as a girl because of some mutation that renders the key male determining gene on the Y chromosome inoperable.”
Georges is a professor and chief scientist at the University of Canberra’s Institute for Applied Ecology. He and his colleagues combined field data from 131 wild-caught adult lizards with controlled breeding experiments.
Among the caught lizards, the researchers identified 11 sex-reversed individuals. For this species, the lizards have a ZZ/ZW system of chromosomal sex determination. A ZZ is male and a ZW is female. The system is similar to that of birds.
For the 11 sex-reversed animals, however, individuals had male ZZ chromosomes yet were anatomically female. What’s more, they could reproduce and often became supermoms within their population. As Georges said, “dads make better mums,” at least in this case.
“We showed that sex-reversed individuals, ZZ females, are larger more robust individuals and lay twice as many eggs as normal ZW females,” he added. “Dads reversed to become mums make better mums than ordinary mums.”
The 11 sex-reversed lizards were caught near the border of the Australian central bearded dragon’s range, close to the border of Queensland and New South Wales. This is a semi-arid region that tends to get hotter than the rest of the lizard’s range.
When the offspring themselves later mated with others, their young were more likely to be sex reversed, presumably because of an inherited propensity.
Sex reversals have been reported in other animals too. The phenomenon is common among fish, happening because of aging, environmental temperature, and other factors. It has also been reported in amphibians, but only in a lab setting so far.
In terms of people, Georges said, “Sex reversal occurs occasionally in humans, and presumably in other mammals, but usually comes to attention because the individuals present with clinical symptoms.”
“In some cases, though, it can come as a complete shock to a man to discover that he has XX chromosomes, or for a woman to discover that she has XY chromosomes,” he added.
There is little chance, though, for climate to influence sex determination in humans. Georges said that “the developing embryo is buffered from temperature variation,” given that it is within its mother’s body.
Read more at Discovery News