Scientists trying to determine where dogs were first domesticated have been sent back to the drawing board by a new study. Back in 2002, researchers sampled DNA from dogs around the world, and determined that dogs in East Asia had the most genetic diversity, suggesting that the species originated there and that dogs in that region have had the longest time to evolve. But the new study suggests that those earlier results were skewed, because DNA sampling of African street dogs has revealed equal genetic diversity.
The earlier findings may have been thrown off because the large-scale study included both purebred dogs, whose evolution has been closely guided by human hands, and street dogs, who have bred more autonomously and randomly, and who therefore show more genetic diversity. But the 2002 researchers drew DNA from different types of dogs in different regions. Says Adam Boyko, lead researcher of the new study: “I think it means that the conclusion that was drawn before might have been premature. It’s a consequence of having a lot of street dogs from East Asia that were sampled, compared to elsewhere” [BBC News].
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The oldest known tree-dwelling vertebrate lived 30 million years before the dinosaurs, scientists have found. The animal, known as Suminia getmanovi, had opposable thumbs and long hands, which would have allowed it to live in trees, according to a study published in the journal Proceedings of the Royal Society B.
A team of researchers found that Suminia, which lived about 260 million years ago, had disproportionately long arms and slender, curved fingers that were well-adapted to grabbing tree branches. But perhaps most importantly, one finger on each hand and foot was “opposed” to the rest, much like a thumb. “It’s the first time in the fossil record that we’ve seen evidence of an opposable thumb,” [said lead researcher Jorg Frobisch], adding that the creature was an early ancestor of mammals [BBC News]. The 12 well-preserved Suminia skeletons the scientists analyzed, which were found in Russia the 1990s, predate by 100 million years what was previously thought to be the earliest tree-dwelling animal.
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Changes in an organism’s genome that once took years to make in a lab can now be done in a fraction of the time, thanks to a new method of genome engineering. “This technique allows us to do some amount of rapid evolution” [New Scientist], says lead researcher Harris Wang.
In the experiment, the scientists used a technique called Multiplex Automated Genome Engineering, or MAGE, to program E. coli bacteria to produce five times as much of an antioxidant called lycopene than normal. In addition, using the process, which grafts pieces of synthetic DNA into the genomes of dividing cells, researchers generated 15 billion different genomic patterns in just three days. The process would normally take years, and could eventually be used to produce industrial chemicals, drugs, fuel and anything else that comes out of bacteria [Wired.com]. The process is significantly faster than previous techniques, in which scientists had to modify genes by changing bases one by one, for example, or by cutting genes from one genome and gluing them into another, modifying and inserting them one at a time.
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Scientists have long known that chimpanzees and other nonhuman primates can become infected with simian immunodeficiency virus, or SIV, a variant of HIV. It was thought, however, that only Asian macaque monkeys could die from the infection. But a new study published in Nature contradicts this assumption by finding that the virus can also be deadly to chimpanzees, humans’ closest relatives.
Some wild primates appear to have developed a way to keep SIV from becoming deadly, and scientists had hoped that studying chimpanzees could reveal how this mechanism works, possibly opening to the door to a human remedy. The new results suggest that it will not be possible to find the key to HIV immunity in the chimpanzee genome, as scientists had hoped. However, the study… sets the stage for researchers to gain insight into how HIV and SIV cause disease in their hosts by studying the responses of different primates to the viruses [Nature News].
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Why does a wiener dog look like a wiener, with its body poised on such short, stubby legs? Researchers say they’ve discovered the answer in a single genetic mutation that’s found in dachshunds, corgis, basset hounds, and other short-legged dog breeds. Study coauthor Heidi Parker says this gene may turn on growth mechanisms at the wrong time during foetal development, stunting the growth of long bones in the leg and making them curvy. The trait affects only the legs, unlike the small-all-over effect seen in miniature or toy breeds, such as poodles [Reuters].
The mutation popped up sometime after modern dogs diverged from wolves, researchers say, and it’s a dominant gene–meaning that a dog with only one copy of the gene will show obvious signs of it. Having joined the genetic repertoire of dogs, the gene was available for selection by dog breeders whenever they wanted to develop a downsized breed. The basset hound, for example, was bred for its short legs so people on horseback could keep up with it during hunting, Dr. Parker said [The New York Times].
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Lightning may have produced an important source of food for the planet’s first microbes: a rare form of phosphorus, according to a study published in Nature Geoscience.Researchers examined 10 chunks of sand melted together by lightning, formations called fulgurites, and found a high concentration of the minerals phosphite and hypophosphite in five of them. The soil surrounding the fulgurites contained only phosphate, not phosphites, suggesting that the lightning itself gave rise to phosphites.
“When lightning strikes, it acts like a mini smelter, and the organic molecules strip off oxygen from the phosphorus” [Scientific American], says study coauthor Matthew Pasek.The fact that microbes still have the machinery to digest these phosphites has long puzzled scientists, since phosphites are much rarer than other forms of phosphorus. Lightning forges about two to three tons of the [phosphite] compounds each year, barely enough for life to take notice. But modern bacteria still retain the ability to eat phosphite, which may be a holdover from antiquity [Discovery News].
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Of all vertebrate animals, turtles have one of the stranger body plans. Unlike all other four-limbed critters, which have their shoulder blades riding on the outside of their ribs, the turtle’s ribs are outside of its shoulder blades. This allows turtles to make their shell out of fused bones–the only animal to do so [ScienceNOW Daily News]. Now, scientists have determined that embryonic turtles develop this set-up through a neat bit of origami.
Researchers compared the developing embryos of turtles, chickens, and mice to watch for the point at which turtle development diverged. At first a turtle embryo grows much like a chicken or mouse. But then the developing body wall makes a critical fold, and the usual body plan starts to become an unusual turtle…. The developing muscle tissue that would lie along adult ribs in a standard amniote began to fold underneath itself in the turtle. This tissue tucked inward, bending up to lie below the developing ribs. On this kinked-under section, the shoulder blades, or scapulas, formed [Science News].
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Cotton-top tamarin monkeys can distinguish between “right” and “wrong” grammatical patterns, according to a study published in the journal Biology Letters. The findings suggest that humans share the ability with other species to identify certain patterns that are crucial to spoken communication.
Researchers wanted to find out if the monkeys, which do not communicate using spoken language, could recognize grammatical sequences. To do this, the scientists familiarized the monkeys with a series of sounds and patterns. They did this by first playing recordings of humans saying two-syllable nonsense words, and familiarized the monkeys with either a prefix or a suffix. “In the prefixation condition, they heard ’shoy-bi’, ’shoy-la’, ’shoy-ro’ and so on,” explained Ansgar Endress, lead author of the study. “The idea is that they get used to the pattern if you play it long enough” [BBC News].
The next day the scientists played new words for the prefix monkeys, but this time included some words in which the prefix had been changed to a suffix, like “na-shoy.” (They did the reverse for the suffix monkeys.) The scientists hypothesized that when the monkeys heard this “incorrect” sequence of sounds, they would be more likely to look at the loudspeakers from which the sounds were coming, the same way a human would. For example, if a person said he or she “walked to the store,” and then [used] the word “edwalk” instead of “walked,” the listener, used to hearing “walked” might stare at the speaker as if to say, “Huh?” [Discovery News].
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Japanese giant hornets can wreak havoc on a hive of Japanese honeybees, slicing off the heads of worker bees, feeding on the hive’s honey, and carrying back the larvae to feed to their own young. But the native bees do have one effective defense against the giant marauders, and it’s a battle plan that uses the bees’ one clear advantage: numbers. When a hornet scout appears, hundreds of bees instantly swarm around the invader in what’s known as a “bee ball.” In a new experiment, researchers say they’ve determined exactly how the bee ball kills.
Previously, scientists thought that the heat generated by the mass of vibrating bees killed the hornet. But in the study, published in the journal Naturwissenschaften, researchers found that temperature alone can’t do the trick. The hornets “can survive for 10 minutes at a temperature up to 47C (or 116 degrees Fahrenheit), and the temperature inside the bee balls does not rise higher than 46C” [BBC News], says lead author Fumio Sakamoto. The researchers determined that increased carbon dioxide levels inside the bee ball also plays a role.
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Don’t be alarmed, but on a remote island in Scotland the sheep are shrinking.
Instead of gradually increasing in size as expected due to evolution, the average weight of the wild sheep has decreased as average temperatures heat up. The discovery shows that a species’ response to global warming can be unpredictable, and can be based on multiple factors. According to a study published in Science, warmer and wetter winters have made it easier for smaller sheep to survive the hard months and go on to bear offspring, thus passing these “small” genes onto the next generation of sheep.
Since 1985, the average weight of the wild Soay sheep living on the island of Hirta has decreased by about 5 percent. Due to global warming, the winters on the Scottish isles are becoming becoming shorter and milder. That makes food more abundant and allows some of the smaller, more vulnerable and younger sheep to survive. Then they go on to have offspring that tend to be small themselves — and have a better chance of survival because of the increasingly mild winters. “The environmental and evolutionary processes are intertwined. There’s still natural selection, but it’s not leaving as big a signature as it used to. There’s still a disadvantage to being small, but not as much” [Time], says lead researcher Tim Coulson.
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In the heat and humidity of the tropics you might expect that mammals take it slow and easy–but on the genetic level, they’re accelerating past their mammalian relations that live in more temperate zones. A new study has discovered that tropical mammals are accumulating mutations more quickly and are therefore evolving faster, in a finding that could help account for the phenomenal biodiversity of the rainforests. But the study’s unexpected results have posed a puzzle for biologists. “[It's] an empirical pattern that is begging for an explanation” [The Scientist], says evolutionary ecologist James Brown, who was not involved in the current study.
Previous research had shown that plants and marine microorganisms evolve more quickly in the tropical zone near the equator, but scientists believed that pattern would hold true only for cold-blooded creatures, whose body temperatures and metabolisms are determined by the temperature of the surrounding environment. Scientists believe that this link between temperature and metabolic rate means that, in warmer climates, the germ cells that eventually develop into sperm and eggs divide more frequently. “An increase in cell division provides more opportunities for mutations in the population over a given time,” explained [lead researcher Len] Gillman. “This increases the probability of advantageous mutations that are selected for within the species” [BBC News]. But this mechanism wouldn’t work in warm-blooded mammals, whose body temperatures remain roughly constant regardless of environmental factors.
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A husband and wife team that for 35 years has researched finches’ evolutionary responses to environmental changes have won the prestigious Kyoto Prize in the basic sciences category. Peter and Rosemary Grant, both emeritus professors at Princeton University, have studied finches that lives on the Galapagos Islands for decades and will share the $515,000 prize. The Kyoto Prize is a Japanese award similar to the Nobel Prize.
The two evolutionary biologists devoted their careers to furthering Charles Darwin’s theory of evolution. Both 72, the Grants have been traveling regularly since 1973 to the Galápagos, the remote islands west of Ecuador. There, they have painstakingly recorded the characteristics of numerous varieties of finches [Philadelphia Inquirer]. Darwin stumbled upon these finches during his famous tour of the Galapagos Islands in 1835, later chronicled in his book The Voyage of the Beagle.
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A reproductive strategy is essentially a cost-benefit analysis, as each organism has to determine how much energy to expend in its mating efforts. Most males, including humans, arrived at a strategy of producing vast amounts of tiny sperm, in hopes that among many matings, a few lucky sperm will manage to fertilize eggs. But some unusual organisms take a different approach and produce small amounts of “giant sperm,” and a new study reveals that some organisms had adopted the strategy as early as 100 million years ago.
The giant sperm strategy is found in a handful of modern organisms, including the fruit fly, which is only a few millimeters in size but can produce 6 cm-long (2.5 inch) coiled sperm…. Now the discovery that ostracodes, an extinct ancient class of arthropods, displayed the same trait shows that making giant sperm is a long-standing and evolutionarily successful reproduction strategy [Reuters]. Using a sophisticated imaging technique to study the fossilized soft organs in a tiny ostracode, a bivalve creature only one millimeter long, researchers proved that expending a great deal of energy to produce giant sperm has paid off for some species. “Now we can show that in spite of the costs, it must be a successful way to reproduce, since it ’survived’ for such a long time” [LiveScience], says lead researcher Renate Matzke-Karasz.
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Rats in laboratory tests learned to gamble based on a system of punishments and rewards, strategizing like human gamblers. And when researchers tweaked the animals’ brain chemistry to mimic that of humans with a gambling addiction, the mice began taking risks like pathological gamblers, according to a study published in the journal Neuropsychopharmacology.
To create this animal model of gambling addiction, researchers created a system in which options that could bring greater rewards also could yield stronger punishment. In this case, however, instead of gambling for money, the rats aimed to get as many sugar pellets as possible. The rodents were placed in specially built boxes whose walls incorporated four “response holes.” Each opening was associated with a possibility of earning treats – from one up to four, depending on the aperture chosen. When an animal poked its snout into a hole, the movement would break an infra-red light across the opening, signaling a computer with a “probabilistic” reward-punishment schedule to assign a pellet win or a “timeout” loss. Playing against the clock, the rats had only 30 minutes to accumulate as many sugar pellets as they could [The Canadian Press].
The rats quickly caught on that by choosing the openings that offered the greatest number of pellets, they also risked the longest time-outs during which they could not play the game. The test was based on an evaluation for decision-making in humans called the Iowa Gambling Test. In that game, there are some “bad” decks of cards that offer high rewards and punishments, and other “good” decks that offer lesser rewards and punishments.
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Most paleontologists believe that a group of dinosaurs evolved into today’s birds, but in trying to understand that gradual process they’ve been bedeviled by some details. Yesterday, researchers announced that they may have solved one of those small conundrums. A fossilized dinosaur found in China appears to settle the matter of exactly how the bones in dinosaurs’ feet evolved into the digits hidden in bird wings.
The newly discovered ceratosaur belonged to a group of dinosaurs called theropods, which are thought to have given rise to modern birds and which included the mighty Tyrannosaurus rex. But unlike its T. rex cousin, this ceratosaur appears to have been a vegetarian. Says study coauthor James Clark: “It’s a really weird animal – it’s got no teeth, had a beak and a very long neck, and very wimpy forelimbs…. Then when we looked closely at the hand, we noticed it was relevant to a very big question in palaeontology” [BBC News].
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