This will be the last edition of my Weekly Science Fix blog for this year! I wish you all a new year filled with health and happiness and loaded with science and reason!
Science at Atheist Universe
VIDEO THE WEEK: An amazing chance encounter with a troop of wild mountain gorillas near Bwindi National Park, Uganda. So peaceful! Watch baby gorillas and a female touch and attempt to groom a photographer while the silverback watches very close by. I watched it several times. It must have been so thrilling.
More great videos at the AVM Video Thread.
In the group SCIENCE! we have a goodies-loaded discussion called Science Bits, News and videos, that I encourage you to visit often. This week, check out the last comment: an excellent piece of science blogging by PZ Myers on why primates (and thus, women) menstruate. Most mammals do not menstruate; this is because they do not cycle their uterine linings, they build up a thickened endometrium only if fertilization occurs. This seems to be more efficient than building a thick endometrium like we do, even if there is no fertilization, that then we have to get rid of. Only primates (though not all), a few bats, and elephant shrews menstruate. Why? The answer may involve maternal-fetal conflict. The mother and fetus have an adversarial relationship: the mother’s best interest biologically speaking is to have several pregnancies and offspring, so the body tries to conserve resources for the long haul, while the fetus tries to use resources maximally to its benefit, even if it’s in the mother’s long term detriment. Could preventively building a thick uterine lining a question of self-defense for the mother? All menstruating mammals have the most invasive type of fetuses, called hemochorial; the placenta not only pierces the uterine lining, but actually breach the maternal blood vessels. Waiting to build a thicker uterine lining after fertilization could be “too late” for mammals with “greedy” embryos and fetuses and very invasive placentas.
EVOLUTION: Evolution, A Book That Turns Science Into Art. The Smithsonian calls our attention to a beautiful book by Jean-Baptiste de Panafieu, photographs by Patrick Gries. The book uses skeletons, traditionally used to illustrate evolution ever since Darwin, is organized into essays about various topics in evolution, and each illustrated by a set of skeleton photographs. For example, the co-evolution of predator and prey species, for example, includes images of a leopard skeleton attacking an antelope, an eagle swooping down on a rabbit and a red fox pouncing on a common vole. It is written for lay people but apparently also chock-full of new facts that will keep the interest of people familiar with evolution. But given the beauty of the photographs, the book could be bought just to look at the images! Is anybody is thinking of making me a last-minute gift for the holidays, here is your hint! (I’m only kidding, of course; I will buy the book for myself as a self-gift).
COMPARATIVE ANATOMY: The elephant’s sixth toe. Although that elephants have a sixth "toe" has been known since the 18th century, it is news to me, and I'm pretty sure it would be for most of you. The elephant's 6th toe is not a true toe but it is the evolutionary equivalent of the panda's "thumb", an extension of a sesamoid bone. Sesamoid bones are bones embedded within a tendon, where the tendon passes over a joint (in humans, the most prominent is the patella or knee cap, embedded within the quadriceps tendon; we have sesamoid boners in our hands and feet too). In elephants the sixth toe is found both in their front paws and back paws. Elephant feet may look flat, but that's only because they are fat (they have a huge fat pad). Actually elephants stand and walk on their toes, just like horses and dogs. A Science report this week finally solves the issue of how the sixth toe functions. This has been very difficult to investigate because the fat and thick keratin structures of the elephant's foot prevent the use of probing instruments such as ultrasounds and X-ray imagining in live elephants while they move. The scientists cleverly used dead elephants to study this: they statically loaded the feet, separated from the body, while performing CT scans. The sixth toe on the front feet basically as weight support, and does not rotate, but the back sixth toe is more mobile and functions as a dynamic lever. The sixth toe is in the aquamarine color in the figure, labeled "pp", for prepollex in the front feet (or "manus"); and "ph" for prehallux, in the back feet, or "pes" in anatomical lingo. The article also explores these pre-digits in fossils of elephant ancestors. While the earliest ancestors were not very large, they had flat feet, and no sixth toes, but as they evolved into giants, the tip-toe stance evolved, their legs straightened in order to support their weight, and the one of their sesamoid bones evolved into a sixth toe to share the load.
ENTOMOLOGY: A naturally diamond-studded beetle. An inordinate fondness for beetles: this is what the great British geneticist and evolutionary biologist, JBS Haldane, an atheist, reportedly answered to theologians who asked him what could be concluded about the "Creator" from the study of his creation. Indeed, there are beetle species (Coleoptera) than any other type of insect, and more species of insects than any other group of animals in the world. Not only there are many types of beetles, but they also include some truly extraordinary creatures. One of them is the diamond weevil. Its hard wings are covered by pits that contain hundreds of teardrop-shaped, sparkling, rainbow scales. The function of the iridescent scales is not know; one hypothesis is that they can be used in communication, for example to attract mates. A new study has now elucidated the nature of the scales and how they reflect light. The scales are a type of 3-D photonic crystal, reflecting a specific light wavelength according to the orientation. They are actually diamonds, in the sense that they are crystals made of chitin (a biological polymer found in arthropods), and their structure is the same as actual carbon diamonds. The structure is called "diamond cubic." Each scale is divided into sections of iridescent colors; as the angle of the light hitting the sections changes, so does the color reflected off the scales. A scanning electron microscope was used to further probe their structure. The scale contains a 5 microns thick-like waffle-like layer, that looks like little hexagons in juxtaposition. The tiny scales reflect blue-green light from the square parts of the crystal and orange-yellow light from the hexagonal sections. This is not only fascinating from a biological point of view, but engineers can potentially copy nature and create new solar cells, electronic screens or even paints based on this structure.
ASTRONOMY: Cassini to make a double play. Michel tells us: "I'm a huge fan of the Cassini spacecraft. Not only because it is exploring one of the most intriguing planetary system, but because it is doing it so far away from us and with such an incredible precision. And it executes its finely tuned choreography in what could be described as an extremely turbulent gravity soup. Cassini goes a long way in showing that science works. The number of "predictions" required to perform this fantastic ballet and all the scientific experiments it is tasked with is, well, astronomical. To get an idea of what a feat this is, Saturn's maximum distance from Earth is 1,658,854,980 Km and it takes more than 3 hours before you get an acknowledgement of the command you sent to the robot".
Go to the discussion to view astonishing actual photographs of Saturn and moons, taken by NASA’s Cassini spacecraft, for example this one of Titan and its third largest moon, Dione. This is an actual photograph, not a drawing or computer graphic.
Science bits and news from other sites:
The year in science photographs: Nature News From Nature News (Nature magazine): 365 days: Images of the year. Flying rhinos and furious rats vie with graphene knots and space technology in 2011’s most striking pictures. Science saw farther than ever this year, glimpsing new wonders in the microworld and in the distant reaches of the Solar System. But some of the most powerful images were taken at an all too human scale, as the earth shook, volcanoes blew and mankind continued to threaten other species’ survival. Please go to the site for a look at what Nature considers the 11 most striking images of 2011; there are some strange choices in there, but all of them will make you think. Do not miss the aggressive rats! Here I show you: CELLULAR CHRISTMAS: Donna Stolz created a festive wreath by assembling images of mammalian cells from more than 25 experiments. The picture adorned her Christmas card last year and won recognition for the University of Pittsburgh biologist in the 2011 Nikon Small World photography contest.
Probing a Black Hole. How do you probe a supermassive black hole? Take a look at the pulsars that orbit it. These rapidly spinning neutron stars flash regular radio pulses, and in an upcoming issue of The Astrophysical Journal astronomers say that the timing of such pulses could provide a new understanding of the 4 million-times-solar-mass black hole at the center of the Milky Way. Scientists have speculated that physics as we know it could break down in the presence of such a strong gravitational force. If that's the case, any flashes from nearby pulsars would appear to speed up or slow down when viewed from Earth, with their clocklike arrival times running early or late and likely dependent on where their orbits were in relation to the black hole. In the process, the astronomers also hope to determine Sagittarius A*'s spin rate and true mass down to an accuracy of about 1 part in a million. First, though, they have to find pulsars close enough to this gravitational monstrosity to be useful. And that's not expected to happen until the Square Kilometer Array comes online early next decade.
Geologists Find Source of Stonehenge’s Inner Stones. A team of geologists from Britain has pinpointed the exact quarry where the rocks at the innermost circle of Stonehenge’s came from. The origin of the rocks was identified using petrography (evaluation of mineral content and texture). The inner circle is composed of spotted dolerites or bluestones. Surprisingly, the data point to a site called Craig Rhos-y-Felin, in north Pembrokeshire, 160 miles from Stonehenge. But how did theses rocks made it to Stonehenge. Did neolitihc people somehow transport these huge rocks for 160 miles? Or were the chunks of rocks deposited at Stonehenge by glaciers, >100,000 years ago? By contrast, the outer stones, huge sarsens, came from somewhere in the Marlborough Downs, 20 miles north of Stonehenge.
The Perfect Gift This Holiday Season: The Neanderthal Test. If your ancestry is from anywhere in the world excluding Africa, you probably have some Neanderthal DNA in you. I have personally always been convinced of that, half jokingly, because of my large bone structure. Other times, I look at people faces and even “see” the Neanderthal in them: a guy with a particularly heavy brow or very large chest, etc. The truth is that we do not what those vestiges of Neanderthal DNA produce in terms of phenotype: we have no idea if they have any consequence that can be spotted in the appearance or behavior of modern humans, as much as we would like to be able to label certain people as “cavemen” (or “cavewomen”. But now you can give the presumed cavepeople in your family the perfect Xmas gift, or you can satisfy your curiosity as to what % of Neanderthal you are carrying in your genome. The personal genomics company 23andMe, developed a test that quantifies the percentage of variants that came from our extinct ancestors, and they will report that together with alleles that are markers of a certain ethnic background, and variants that represent risk for certain diseases. The average is 2.5% in non-Africans, what would your % be? Blogger neuroscientist David Dobbs tweeted that he is 3% Neanderthal, when he got his results, he skipped health and ancestry and went straight for the Neanderthal! He was congratulated profusely by his tweeps for that high Neanderthal percentage!
How diving marine mammals manage decompression. Decompression sickness (DCS), also known to divers as "the bends," can occur if the ascent is too abrupt, due to gases that had been absorbed as a result of increased ocean pressure during a deep dive coming out of solution and forming bubbles in different parts of the body. The effects vary from joint pain and rashes to paralysis and death. Have you ever wondered how marine mammals manage to avoid DCS? The hypothesis was that something in their physiology prevented them from getting DCS, but new data just published in the Proceedings of the Royal Society B. suggest that marine mammal actively avoid DCS by behaving in certain ways, not just by physiological adaptations. Although marine mammals do not get DCS routinely, they can suffer the damaging effects of bubbles under certain stressful conditions. A necropsy of beached whales in the Canary Islands showed evidence of damage from gas bubbles. The whales became stranded after exposure to sonar from nearby naval exercises, which causes great stress in these marine mammals. This may mean that marine mammals deal with nitrogen bubbles more frequently than previously thought. Under normal conditions, a marine mammal feeling symptoms of DCS may simply dive down again (this is what divers do to deal with DCS) but if the animal is in shallow water or beached, they can’t deal with the bubbles, and they can suffer permanent damage, just like human divers.
Small Spiders Have Big Brains That Spill Into Their Legs. Researchers at the Smithsonian Tropical Research Institute and a professor at the University of Costa Rica studied 9 spider species from the perspective of brain and nervous system size, and they found that the smaller the spider, the bigger its brain relative to its body size. In some tiny spiders, the central nervous system took up to 80 % of their bodies, even going into their legs! It is presumed that they need such a large central nervous system to have the ability to weave complex webs. However, at least 3 kleptoparasitic spider species, that do not spin webs but instead steal prey from other spiders, also have big brains. The stealthy thieving behavior is also complex and may therefore require a large brain, too. But how do the other organs manage to function in such a restricted space? This questions remains unanswered.