VIDEOS OF THE WEEK: What a trip through a wormhole would look like. In physics, a wormhole is a hypothetical feature of space-time, a "shortcut" through space-time. If we could travel through one, we could end up in a galaxy millions of light years away. Of course nobody would survive the journey, but thanks to an animation by astrophysicist Andrew Hamilton from the University of Colorado at Boulder, we can visualize what the journey might look like.
Evolution in a big city. Using newts, coyotes and mice, Jason Munshi-South shows how animals develop genetic differences in evolution, even within an urban city (New York City).
More great videos can be found in our discussion Science Bits, News, Videos
And more EVOLUTION:
Carnivores lost a sugar-tasting gene through evolution. Carnivores have impressive teeth, but no sweet tooth. Since they have specialized in meat-eating, many carnivores have accumulated mutations in a gene encoding a sweet-taste receptor, Tas1r2. Felines, including house cats, tigers, lions, cheetahs, all have an identical inactivating mutation in this gene. This makes sense, because they belong to the same family. In a recent study, the DNA of 12 more mammals of the Order Carnivora, as well as a bunch of marine mammals, was analyzed for mutations in this gene. Seven of these species, including hyenas, and several seal species and sea lions as well, all had inactivating mutations in this gene. All land carnivores analyzed had different Tas1r2 mutations; sea lions and fur seals had the same mutation, but Harbor seals (more distantly related), had a different one. This is a case of convergent evolution; these carnivores lost the ability to taste sugar independently, as reflected by the different mutations. It's not that losing the ability to taste sweets was selected for, but rather than inactivating mutations were not selected against, since these animals eliminated vegetables from their diet and had no need to taste sweetness. DNA analyses also revealed that bottlenose dolphins and fur seals lost the ability to taste umami (savory), as well, and dolphins also lost the capacity to taste bitter. Dolphins swallow their food whole so it appears that taste is not crucial to their survival. Interestingly, most mammals have a functioning Tas1r2 receptor, and is very conserved through evolution, which indicates that this receptor plays an important function.
HUMAN EVOLUTION: Pleistocene human fossils from Southwestern China highlight the complexities of the hominin family tree. Although these fossils are being called a potential new species, it is premature to label these late Pleistocene specimens, only about 11,000 to 14,000 years old, as an entirely new human lineage. Nevertheless, the bones, representing 5 individuals, including a well preserved skull, are clearly “funny-looking.” The skull has modern human features as well as some archaic traits and also quite unique traits. The fossils come from southern China, and are being called by scientists, the Red Deer Cave (Maludong) people. The fossils have been in Chinese collections since the late 80s but a detailed analysis was carried out just now and published in PLoS One. The skulls have rounded brain cases and prominent brow ridges with short and flat faces and broad noses. The jaws do not have a modern human chin, and their molars were large (taurodont molars). A scan of the brain cavity revealed modern-looking frontal lobes but archaic-looking parietal lobes. The scientists propose two theories for their origin. They could represent a late-surviving archaic population, from a very early migration of a primitive-looking Homo sapiens that co-existed with modern-looking Homo sapiens in neighboring areas and then they died out. Another possibility is that East Asia could have been colonized during multiple waves during the Pleistocene, and the Red Deer Cave people reflecting a deep population substructure in Africa prior to modern humans dispersing into Eurasia. DNA could not be extracted from the remains, unfortunately. The bottom line is that these fossils add to the increasingly complex story of human evolution, migration and development.
ENTOMOLOGY: Daredevil bees and drunken fruit flies!
The secret personalities of bees. Are some bees adventurous and some more timid? These are the sort of personality traits that we attribute to mammals, birds, and possibly other vertebrates. Scientists have now determined that some bees are indeed more adventurous than others. And what is even more interesting is that the brains of adventurous honeybees show distinct patterns of gene activity, in molecular pathways that we know are associated with novelty-seeking in humans. Novelty-seeking behavior in bees is seen in scouting, for either new nesting or new food sites, and approximately 5% of bees leave the hive to go in search of new places to build or collect food. These bees are the ones displaying the brain gene activity similar to the mammalian brain thrill-seeking signature, in the dopamine and glutamate pathways. To confirm that the gene expression pattern corresponds to the novelty-seeking behaviors, scientists gave bees glutamate and octapamine, and observed an increase in scouting behavior in bees that normally didn't scout. Conversely, dopamine administration resulted in reduced scouting behavior. The molecular mechanisms are thus the same as seen in vertebrates. It seems that life has only so many tools in its genetic toolkits, and that even distantly related life forms such as insects and vertebrates, end up coming back to the same molecular pathways to produce certain behaviors. Evolution keeps coming back to the same well for the same end result. What a process!
Sexually frustrated male fruit flies turn to alcohol. It sounds like a stereotype behavior from a cheesy soap opera. Researchers found that male fruit flies that do not get an opportunity to mate consume 4 times more alcohol than male fruit flies that had mated. Fruit flies naturally consume some alcohol as part of their diet because fruit is their source of food of fermented, over-ripe fruit contain alcohol. The experiment was as follow: they places male fruit flies in either of two situations: inside a glass tube with many females ready to mate, where the males mated several times, or in a glass tube with several males and only one female, that had already mated and therefore rejected the males' courtship. After 4 days of this treatment, the male flies were placed in a container where they had the choice between alcohol-soaked fruit or non-alcohol containing fruit. The sexually rejected flies preferred the alcoholic fruit, and ended up consuming much more alcohol than the contented flies. The interesting part is that the same "pleasure" pathways are activated in brains of the fruit flies that get drunk than in people who drink alcohol. The flies were "self-medicating", or even more dramatically put, "drowning their sorrows in alcohol". Even more interestingly, the sexually rejected flies had half of the amount of neuropeptide F (NPF) in their brains than sexually satisfied males. NPF is known to be linked to alcohol consumption. If NPF was activated in the brains of the frustrated males, they did not turn to alcohol. Mammals a similar molecule, neuropeptide Y (NPY). People with depression and PTSD have been shown to have lower levels of NPY. Lab rats with low NPY consume more drugs. In humans, certain gene variants of NPY (polymorphisms) have been found to be more common in heavy drinkers. Obviously it would be premature to find parallels between the flies and human behavior, but the study suggests some connections, and opens up the possibility of future studies.
VOLCANOLOGY: Awoken caldera is moving Santorini. The beautiful volcanic island of Santorini is being pushed and pulled in different directions by its caldera. Georgia Tech scientist Andrew Newman has been studying the volcanic activity in Santorini since 2006; he has set up more than 20 GPS stations on the island to measure the movements of the Santorini caldera. After decades of inactivity, a series of earthquakes started happening within caldera in 2011. GPS measurements indicate the island has moved laterally between five and nine centimeters! The magma chamber of the volcano is filling up, it has expanded by 14 million cubic meters since last January. But at this point is not possible to predict if an eruption is imminent because the measurements are insufficient, and similar calderas around the globe have shown similar behavior without erupting. If the caldera erupts underwater, it could cause local tsunamis and affect boat traffic, in addition to earthquake damage of properties on the island. One of the largest volcanic events in human history occurred in Santorini around 1650 B.C.E. The eruption was known as the Minoan eruption, and it buried the major port city of Akrotiri with more than 20 meters of ash. The eruption created the cliffs that now make the island famously beautiful. Such an eruption comes along once every 100,000 years, and the current inflation in the magma chamber is less than 1 percent of the Minoan blast, so the island is not in huge danger at the moment.
Science bits and news from other sites:
March 14th was Pi day. Ethan Siegal, from the great blog Starts With a Bang, has a fun post in honor of Pi Day, a tongue-in-cheek “celebration” here in the United States, as 3.14 is March 14th (in the US, the month is written before the day). As you all know, Pi is the ratio of the circumference of a circle to its diameter. Pi is an irrational number, therefore it’s very hard to represent exactly as a fraction. Siegal tells us about Archimedes, who 2,000 years ago calculated the first approximation of Pi (the fraction 22/7, which is why Pi Day is July 22 in Europe. He used a 96-sided polygon to approximate a circle, and found that π was between 220/70 and 224/71. But Chinese mathematician, Zu Chongzhi, who, in the 5th Century, came up with 355/113 = 3.1415929, a most impressive approximation in those days, because it went to the eight digit. Read the entire blog for more fun Pi Day facts! Very entertaining.And for eye-candy: Jupiter and venus on Pi Day!
Starling flocks behave like magnetized metal. The huge flocks of starlings (Sturnus vulgaris vulgaris) are known scientifically as murmurations. They involve thousands of birds, and they occur throughout North America and Europe. The murmurations around Rome are very big and very famous. How the birds achieve the extraordinary coordination within the flock is fascinating not just from a biology point of view, but as a physics phenomenon, too. Statistical physicist Irene Giardina of the University of Rome, and her team, have just published an article in the Proceedings of the National Academy of Sciences, analyzing how the flocks achieve their extraordinary coordination. She concluded that starling murmurations behave mathematically like metals becoming magnetized. Previous research resulted in equations describing murmurations in a similar way to snow avalanches. Both are examples of collective phenomena that emerge from short-range interactions. The researchers used multiple video cameras and software to track the trajectories of individual birds, second by second. In 2010 study, Giardina’s group showed that changes in the velocity of any one bird affected the velocity of all other birds in a flock, regardless of the distance between them. In this study, they looked at orientation and they measured how a change in direction by one bird affected others. Changes in orientation (turns) caused only a bird’s 7 closest neighbors to alter their flight. That number stayed consistent regardless of flock density, making the equations topological. Changes ripple quickly through flocks, from one bird to seven neighbors, each of which affected seven more neighbors, etc. The closest statistical fit for this behavior is in the realm of magnetism, in an equation that describes how the electron spins of particles align with their neighbors as metals become magnetized. Giardina’s team will now study flocking in other organisms (midges) with different patterns of collective flight. Different collective behaviors may represent different purpose for the flocking (or swarming. In the case of the midges, it seems to serve the purpose of mating. For starlings, it is a strategy to evade predators. I promise you that you will be mesmerized by the video of a starling murmuration over Rome.
Giant squid, giant eyes. Did you know that giant squid have the largest eyes of any animal? They are about the size of a basketball. In comparison, blue whales eyes are not even as big as the giant squid’s pupils! Why did such huge eyes evolve? Researchers reported this week in Current Biology that the big eyes help the squids spot and escape its main predator, the sperm whale. Vision under water is more difficult than on land because light fades out as depth increases. Water makes distant objects disappear faster. Researchers base their conclusion on a computer model that simulated how well eyes of various sizes could see at different water depths. The modeling showed that basketball-sized eyes could detect whales from more than 120 meters away, giving the squid enough time to avoid the predator. In the dark deep, sperm whales can be seen because their movements disturb small luminescent organisms.
Prehistoric Lobsters Made Homes of Ancient Ammonoid Shells. Fossils are great to look at anatomy, but behavior is a different story. Still, every once in a while we get lucky and find fossils that hint at animal behavior. In this case, a beautiful Jurassic nautilus-like shell (from the cephalopod species Harpoceras falciferum) got fossilized in a peculiar way, and we can observe what was inside the shell. The ammonoid shell thin outer layer, called the periostracum, is a translucent organic layer and when it fossilized, it allowed for a view of its contents. To the paleontologists delight, there were 3 miniature, one inch lobsters crowded inside. The small crustaceans belong to a completely extinct group of lobsters, the Eryonidae, which had compressed, circular bodies with spikes around the rim. Because the 3 lobsters were preserved together, more than halfway inside the coiled shell of the ammonoid, and they were intact, it appears that the little guys were shacking up inside the cephsalopod’s empty shell. Other creatures are known to have congregated inside empty mollusk shells, for example trilobites and extinct small fish that have been found inside the shells of huge clams. Shells have been primarily real estate for many marine organisms throughout the eons. The lobsters could have entered the shell to eat bits of left over cephalopod, or to escape predators. It was not an accident, because the same type of extinct lobster has been found only inside of ammonoid shells, so the two animals had a definitive relationship in that ancient ecosystem. These lobsters most likely specialized in making homes out of empty shells.
New Frog Species Found in New York City New species of frogs are found fairly often, but always in exotic locations such as remote areas of a rain forest, somewhere in the tropics. Who would have thought that a new species of frog would crop up in Staten Island, one if the 5 boroughs of the magnificent urban jungle I call home, New York City. The reason why the new species was incognito is that it looks similar to a common leopard frog. But DNA analysis shows that this new species is genetically distant enough from the common leopard frog, to be called a new species. What tipped the scientists first was that these frogs make a distinct croak, totally different from the two other species of leopard frogs that live along the East Coast of the United States. At first the researchers thought the newly discovered frogs could be a hybrid of the two species, but their DNA shows that they are distant from both. These frogs live in New Jersey, Staten Island, and the Bronx. The center of their range is around Yankee stadium. The team that found the species is now going back to study it more closely so that they can give it a formal description, and come up with a name. Perhaps they will name it after Alex Rodríguez or CC Sabathia.