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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A tiny fish common in European streams may learn in a more sophisticated way than has ever been recorded among animals and which mimics human learning. In a study published in the journal Behavioral Ecology, scientists found that the nine-spined stickleback fish used the success and failures of their peers to gauge where they should seek food.
The fish were shown to display a type of learning known as “hill-climbing,” in which an entity continually looks for a better solution to a problem; in this case, one fish copied others that were more successful in finding food. Researchers caught 270 nine-spined sticklebacks in Leicester, England. The fish were organized into experimental groups. These fish groups then took turns as either free swimmers in a tank with worm-yielding feeders at the end, or as “learners” in a transparent, partitioned-off area of the specially designed tank. One of the two feeders released more worms than the other [Discovery News].
The first group of free-swimming fish quickly learned which feeder was full of worms, and were then put into the observers’ chamber. Next, researchers switched which feeder held the worms, and the fish in the observation tank watched the next fish group identify the new worm-filled feeder. After switching the two groups of fish again, the original group made a beeline for the feeder full of worms that their peers had fed from.
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How life evolved from a mix of chemicals on the young planet Earth is one of science’s most enduring mysteries, which biochemists are attempting to solve by recreating the earliest building blocks of life in the laboratory.
Earth’s biology is based on DNA, which carries all an organism’s genetic information in a molecule that takes the shape of a spiraling ladder. RNA, the molecule that facilitates protein manufacturing, has a simpler shape–it’s a single strand, as opposed to DNA’s double strand–leading some biologists to propose the RNA world hypothesis in which RNA evolved first and eventually gave rise to DNA. But trying to imagine the assembly of RNA from its chemical components poses its own problems. How could RNA, which encodes proteins, first form, when proteins are needed for [its] synthesis? Now, scientists report that they’ve cooked up molecular hybrids of proteins and nucleic acids that skirt the dreaded paradox [ScienceNOW Daily News].
The hybrids they created could resemble the precursors to RNA, researchers report in Science. “It’s the pre-RNA world. There’s a hypothesis that says RNA is so complicated, it couldn’t have arisen de novo” — from scratch — “on early Earth,” said study co-author Luke Leman…. “So you need some more primitive genetic system that nature fiddled around with and finally decided to evolve into RNA” [Wired.com].
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What are fingerprints good for, besides aiding police investigations? That’s the question that biomechanics researcher Roland Ennos recently set out to answer. This notion that human fingerprints (and presumably footprints) evolved because they act like tire or boot tread–increasing the friction against a smooth surface so we don’t slip or drop stuff–is a 100-year-old urban myth that, apparently, had never been put to the test [NPR].
To test the impact of fingerprints, Ennos rigged a machine that measured the amount of friction generated by a fingertip (belonging to study coauthor Peter Warman) when it was pressed against a piece of acrylic glass. Warman gradually increased the pressure, going from a light touch on the glass to a tight grip, but the corresponding friction didn’t increase as much as the researchers expected. Soon they realised that the skin was not behaving like a normal solid, where friction is proportional to the strength of the contact. Instead, it was behaving like rubber, where the friction is proportional to the contact area between the two surfaces [BBC News].
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It may sound like a paradox, but a new theory suggests that one of humanity’s most noble instincts, altruism, evolved on bloody battlefields in prehistoric times. Evolutionary biologist Samuel Bowles argues that prehistoric culture may have selected for individuals who behaved altruistically towards other individuals in their social groups. The story begins with the climactic swings that occurred between approximately 10,000 to 150,000 years ago in the late Pleistocene period may have pushed once-isolated bands of hunter-gatherers into more frequent contact with one another…. “I think that’s just a recipe for high-level conflict” [New Scientist], says Bowles.
These conflicts weren’t large-scale pitched battles, Bowles explains. “We’re talking about groups of men who got out in twos or threes or fives,” he says. “They didn’t have a chain of command and it’s hard to see how they could force people to fight.” For this reason, altruistic intent on the part of each warrior is key. Each person would do better to stay home than to put their life on the line for their neighbours – yet they still went out and risked their lives, Bowles says [New Scientist].
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It’s hard to imagine having more fun in the name of science: In a new study, researchers tickled young chimpanzees, bonobos, gorillas, orangutans, and even a few human babies, and recorded the vocalizations that resulted. Primatologist Marina Davila Ross wanted to examine the evolutionary history of laughter, so she and her colleagues recorded the sounds produced when they tickled 22 great apes and 3 human babies, picking the usual sensitive spots: armpits, palms, feet, and necks.
Scientists have known that great apes vocalize when tickled at least since Charles Darwin’s time. But it was unclear whether these sounds were actually related to human laughter. Now, researchers … have concluded that laughter has been evolving in primates over the last 10 to 16 million years, since at least the last common ancestor of humans and modern great apes [Wired.com].
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The fishing boats that relentlessly sweep the northern Atlantic Ocean looking for cod may be changing the genetics of the species, researchers say, in a case of “fisheries-induced evolution.” Commercial fishing techniques used to harvest the valuable fish are wiping out the cod that swim at shallower depths, which have a genetic variant that’s not seen in cod that stick to deeper water. If overfishing of cod continues, the research team believes the genetic variant will be lost all together. “Man the hunter has become a mechanised techno-beast,” the team writes. “Modern fisheries are uncontrolled experiments in evolution” [New Scientist].
Evolutionary biologist Einar Árnason and his colleagues studied the changing population of the cod fishery around Iceland; it’s one of the largest in the world, yielding roughly 200,000 metric tons a year. The stocks are in far better shape than the collapsed fisheries in the western Atlantic [ScienceNOW Daily News]. In the new study, published in the journal PLoS ONE, the researchers examined how the genotypes of Icelandic cod have changed between 1994 and 2003.
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Researchers have endowed lab mice with the human version of a gene involved in language, and while the mice didn’t exactly sit up and start reciting poetry about cheese, they did show some intriguing differences in both their vocal patterns and brain structure.
Mice have their own form of the gene, called FOXP2, but they and all other animals lack key changes found only in humans and our evolutionary cousins, Neanderthals. Some researchers speculate that these differences may help explain why humans are the only animal able to communicate with complex languages, and not simple grunts, barks or songs [New Scientist]. By tweaking the gene in mice and changing it to the human form, researchers hoped to get a clue as to how our early hominid ancestors were changed by the new form of the gene.
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The explosion of a volcano located in present-day China might have caused a mass extinction 260 million years ago, adding more evidence that volcanoes might have been to blame for some of the world’s most catastrophic die-offs. Because the eruptions occurred in a shallow sea the researchers were able to study both the volcanic rock and the overlying layer of sedimentary rock containing fossilized marine life [AP], giving researchers a better picture of how the explosion altered the balance of life.
The injection of hot lava in a sea would have produced a massive cloud formation that could spread around the world, cooling the planet and producing acid rain [AP], according to the study, which was published in Science and led by paleontologist Paul Wignall. Based on analysis of the volcanic and sedimentary rock at the eruption site, the scientists hypothesized that ash and lava spewed from a sea covering the volcano, showering plants and animals with atmospheric carbon. “When fast flowing, low viscosity magma meets shallow sea it’s like throwing water into a chip pan there’s spectacular explosion producing gigantic clouds of steam” [Telegraph], says Wignall.
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A small, lemur-like creature may have been an early ancestor of monkeys, apes, and humans. A magnificently preserved fossil dating from 47 million years ago reveals an animal that had, among other things, opposable thumbs, similar to humans’ and unlike those found on other modern mammals. It has fingernails instead of claws. And scientists say they believe there is evidence it was able to walk on its hind legs [ABC News].
In a study that will be published in the journal PLoS ONE tomorrow, researchers will report that this extraordinary fossil could be a “stem group” from which higher primates evolved, “but we are not advocating this” [The New York Times]. The fossil was first discovered in 1983 in the Messel Shale Pit, an old quarry near Frankfurt, Germany that has long been a World Heritage Site because of its rich fossil beds. The specimen was excavated by private collectors but was then divided into two parts and sold; it was only two years ago that scientists reassembled the complete fossil and began studying it.
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