| Update:
March 08, 2008 |
| THE EYES HAVE IT |
| By Pam Eastlick for THE DEEP on line |
| Welcome to The Deep science and technology column where we cover topics from the deep sea to deep space and beyond. |
WHEN IS A COMET NOT A COMET?
We’ll start this week with a little news from outer space. Several years ago; the Stardust mission was launched to sample the material given off by a melting comet; specifically Comet Wild 2 (named for the gentleman who discovered it). Astronomers were eager to examine material from comets because they are thought to have formed far from the Sun and to be unchanged remnants of the ice, gas and dust cloud that formed our solar system and Sun.
The Stardust mission had a chamber that was open to space that was filled with Aerogel; the ‘solid smoke’ compound that’s proved so useful to several space missions. Astronomers hoped that the Stardust spacecraft would ‘run over’ microscopic particles from Comet Wild 2 that would become embedded in the Aerogel. The precious Aerogel cargo was returned to Earth in 2006.
When the captured particles were examined, astronomers got a big shock. Not only did they not contain the primitive compounds the researchers expected to find, they didn’t even resemble the particles found in other comets.
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Wild 2 comet sample more closely resembles a meteorite from the asteroid belt; not an ancient, unaltered comet.
This, of course, brings up the whole definition thing again. What is an asteroid and what is a comet? Traditionally, an asteroid is made mostly of rock and a comet is made mostly of several kinds of ices. Since Wild 2 has a tail formed by vaporizing ices it is, by definition, a comet. But these new result are making astronomers realize that they can’t make black and white distinctions between asteroids and comets. There is a continuum between the
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AN ANIMAL ASSEMBLED BY COMMITTEE?
Animal researcher Francesco Rovero had his remote cameras set up in the wilderness of Tanzania in Africa looking for lions and antelopes, but what appeared in the camera lens was like nothing he’d ever seen before. And it turned out no one else had ever seen it before either.
It was the size of a small dog, covered in orange and gray fur, and had a long snout like an elephant. Its markings and general appearance suggested it was a member of the elephant-shrew family, called a sengi in Swahili. Rovero’s fellow scientists have confirmed that he has discovered a new species of giant elephant-shrew.
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It has been named the gray-faced sengi (Rhynchocyon udzungwensis) and it weighs about 1.5 pounds, 25 percent larger than any other member of the elephant-shrew family. It is known to exist in only two groups in a 115-square-mile area of this largely unexplored forest. It’s the first new species of giant elephant-shrew to be discovered in more than 100 years.
Scientists report that its relatives include elephants, manatees, and the aardvark. In recent years, a number of other new species have been discovered here, including the Udzungwa partridge, a monkey known as the kipunji, and several amphibians and reptiles. |
WHERE CATS CAME FROM
The Fertile Crescent of the Middle East has long been identified as a "cradle of civilization" for humans. In a new genetic study, researchers at the University of California, Davis, have concluded that all ancestral roads for the modern day domestic cat also lead back to the same locale.
Archaeological evidence and research on the evolutionary history of cats suggests that the cat first became domesticated about 5,000 to 8,000 years ago in the area around the eastern end of the Mediterranean, stretching from Turkey to northern Africa and eastward to modern day Iraq and Iran. This domestication was mutually beneficial because this is when and where humans began to farm.
Cats, those ultimate hunters of mice, rats and other rodents, became useful companions as people domesticated, grew and stored wild grains and grasses. Of course, the word ‘domestication’ doesn’t really apply. Cats are pets but have never been fully ‘domesticated’. Even today, most domestic cats remain self-sufficient, if necessary, and continue to be efficient hunters, even when provided with food.
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The researchers collected samples of cheek cells from more than 11,000 cats. These cats represented 17 populations of randomly bred cats from Europe, the Mediterranean, Asia, Africa and the Americas, as well as 22 recognized breeds. From the DNA analysis, the researchers found that the cats were genetically clustered in four groups that corresponded with the regions of Europe, the Mediterranean basin, east Africa and Asia.
The study found that genetic diversity remained surprisingly broad among cats from various parts of the world. However the data indicated that there was some loss of diversity associated even with the long-term development of foundation cat breeds -- those breeds that provided the genetic basis from which modern pure breeds were developed.
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WHERE’D YA GET THOSE EYES?
New research shows that people with blue eyes have a single, common ancestor. A team at the University of Copenhagen has tracked down a genetic mutation that took place 6 to 10,000 years ago and is the cause of the eye color of all blue-eyed humans alive on the planet today.
Apparently we all had brown eyes to begin with, but a single genetic mutation resulted in the creation of a switch that literally turned off the ability to produce brown eyes. The gene that gets switched off codes for a protein that’s involved in the production of melanin, the pigment that gives color to our hair, eyes and skin.
turn the gene off entirely however but simply limits its ability to produce melanin in the iris – effectively “diluting” brown eyes to blue.
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The effect is very specific. If the gene is turn off entirely; no melanin is produced resulting in albinism. Eye colors from brown to green can all be explained by variation in the amount of melanin in the iris, but blue-eyed individuals only have a small degree of variation in the amount of melanin in their eyes. From this the researchers conclude that all blue-eyed individuals are linked to the same ancestor. They have all inherited the same switch at exactly the same spot in their DNA. Brown-eyed individuals, by contrast, have considerable individual variation in the area of their DNA that controls melanin production. |
LOOK INTO MY EYES
Do you know when you were born? Well, if you don’t; it turns out your eyes do. Using radiocarbon dating and special proteins in the lens of the eye, researchers at the University of Copenhagen can now establish, with relatively high precision, when a person was born. This is a useful tool for forensic scientists who can use it to establish the date of birth of an unidentified body and it could also have further consequences for health science research.
The lens of the eye is made up of transparent proteins called crystallins. These are packed so tightly together and in such a particular way, that they behave like crystals, allowing light to pass through the lens of the eye so that we can see. From conception until about the age of two, the crystalline proteins of the lens are still being assembled. Once this organic construction work is done, however, the lens crystallins remain essentially unchanged for the rest of our lives.
The proteins of the lens are made of carbon and when they are being laid down a very tiny portion of the carbon atoms are C-14 a mildly radioactive isotope of carbon. Because the material in them doesn’t change throughout your lifetime, your lenses contain a precise record of the C-12 to C-14 ratio of atoms around the time you were born.
From the end of World War II and up until about 1960, the superpowers of the Cold War era conducted nuclear tests, detonating radioactive bombs in the atmosphere. These detonations have affected the content of radioactive trace materials in the air and created what scientists refer to as the C-14 bomb pulse. After the first nuclear detonation and until the ban on nuclear testing was evoked, the quantity of C-14 in the atmosphere doubled. Since 1960, it has been slowly decreasing to natural levels.
This marked change in C-14 levels has been imprinted on the eyes of all of us. Since the crystallins of the lens remain unchanged once they’re created, they reflect the content of C-14 present in the atmosphere at the time of their creation. Physicists can now determine the amount of C-14 in as little as one milligram of lens tissue and thereby calculate the year of birth.
Comets that aren’t comets; strange new animals and startlingly new discoveries about your eyes. Science is a rich feast! Cruise on over to the Deep Website at www.thedeepradioshow.com to learn more about comet, eyes and many other topics. Enjoy!
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Cruise on over to the Deep Website at www.thedeepradioshow.com to learn more about Antarctica, ELR, Jupiter and many other topics. Enjoy!
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