Science News: 7/31/12

This week’s science news update is taking a walk on the weird side. Vampire stars, sneezing monkeys, and stargazing whales? Cool! We also have several hotly disputed studies that were released this week, which, if true, could change what we know about dark matter and early humans and if not, highlight the problems of rushing to press with controversial results.

A recent study of the moon suggests a new possible explanation for its formation: a glancing blow from a massive object. Scientists have known for quite some time that the moon formed after a large amount of material was ejected from the Earth, but they previously thought that Earth collided with a slow-moving object about the size of Mars, dubbed Theia. In this sort of collision, material would have been blasted into space from both objects and given the moon a substantially different makeup than Earth. However, the moon has very similar ratios of rare molecular isotopes, which would mean that most of its material came from the Earth. This would be most likely if a larger, fast-moving object clipped the Earth without being damaged much itself.

Vampires in space! A study of massive O-type stars shows that not only do far more of them exist in binary systems than was previously suspected, but that most of those pairs are close enough together to interact, frequently in the form of one sucking gas from the other or consuming it completely. O-type stars can be up to 15 times larger than our sun, and it now appears that 70% of them are part of binary systems with smaller stars. They are large enough to influence the formation of other stars and release heavy elements when they go supernova.

While recent attempts to detect dark matter on Earth have failed to produce any evidence of its existence, a new study of the center of our galaxy may have detected it. Gamma rays emanating from the center of the Milky Way fit the pattern expected by their formation by random collisions of WIMPs (Weakly Interacting Massive Particles). Other astronomers caution that there could be other explanations for the excess gamma rays, such as undetected pulsars or miscalibrated models, so more research is needed.

Did ancient Africans interbreed with a previously unknown species 20,000 to 50,000 years ago? Geneticists say yes, but paleoanthropologists are hesitant to accept these claims. A genetic study of individuals from three different African groups found “foreign” DNA sequences unknown in other modern people. Evidence has been found in recent years of Neanderthal DNA in modern humans, along with DNA from another extinct Siberian group called the Denisovians, so this sort of discovery is not unheard of. However, no fossil evidence has ever been found of another humanoid species living alongside anatomically modern humans in Africa. The fossil record is far from complete, so it’s possible that one day this mysterious human cousin will be found, but some say that DNA evidence alone isn’t enough to make an announcement of this sort.

Speaking of Neanderthals, what caused them to die off anyway? Speculation has blamed climate change, competition from early humans, or even flat-out being killed off by our ancestors, but a new study suggests that competition is the most likely cause. Neanderthals went into decline about 40,000 years ago and disappeared from Europe about 28,000 years ago. The geologic record shows evidence of a massive volcanic eruption in Italy 40,000 years ago that was followed by a long period of extremely cold weather, and it was long thought that this climate change led to the Neanderthals’ downfall. However, new evidence shows that humans had already developed advanced technology to give them an advantage over Neanderthals before the eruption took place and that the Neanderthals may have already disappeared from some regions. Other researchers are quick to point out that of course this doesn’t rule out any impact the cold would have had on their survival; their decline lasted thousands of years and was likely due to multiple factors.

A species of snub-nosed monkeys known as “sneezing monkeys” has been photographed for the first time in China. Their nostrils are so upturned that it’s said they sneeze when it rains due to water falling into their noses, and they apparently sit with their heads down during storms to avoid this problem. One of several species of snub-nosed monkeys to live in the region, Rhinopithecus strykeri was first discovered in October 2010 and is critically endangered, with fewer than 100 individuals thought to be living in the wild.

Badass gorilla kid news! John Ndayambaje from the Dian Fossey Gorilla Fund spotted a poacher’s snare near a group of gorillas he was studying in Rwanda. As he moved to deactivate it, the silverback grunted to warn him away from it, then two juveniles and another gorilla moved quickly to safely dismantle the snare and another one nearby. Older gorillas have been known to do this, but this shows that the young ones are learning by watching their elders. And while it’s impossible to prove that they were intentionally protecting Ndayambaje from getting ensnared, it’s cool to think they might have been! (Also, fuck poachers.)

Do whales follow the stars? That’s the question researchers are asking after an eight-year long project to track the migratory patterns of humpback whales. After graphing the paths transmitted by satellite tags attached to 16 whales, researchers realized that the whales were swimming in almost perfectly straight lines for weeks on end, regardless of wind and weather patterns or changes in the direction of the current. While many other migratory animals use magnetic or solar navigation, following the earth’s magnetic fields causes far more irregular paths due to its variability and solar navigation doesn’t work in the open ocean because there are no landmarks to correlate where the sun rises and sets. While the whales may rely on these systems in some way, it’s possible they also get navigational cues from the moon and stars or in some way follow whalesongs that can be heard for long distances underwater.

The same RFID tags many people use to track lost pets are now being used to follow much larger animals: Indonesia’s whale sharks. Unlike satellite tags, which are expensive and fall off easily, these radio-frequency ID tags only cost a few dollars and can be used to track the sharks for their entire lives. They can only be read at relatively close range so are useless for the sort of migratory study mentioned above, but since whale sharks frequently feed in the same places the researchers can track their comings and goings. Whale sharks are increasingly popular in the country and Indonesia just this month added them to their protected species list.

A follow up to a genetic study performed on salmon in the 1970s shows evidence that they’re evolving in response to global climate change. The old study introduced a rare yet harmless genetic mutation into salmon that spawned later in the season to track how spawning patterns affected breeding success. When he stopped testing them in 1985, only 3% of early spawning salmon carried the marker, compared with 26% of late spawners. However, later testing showed a marked decline in fish with the marker that occurred between 1989 and 1993, and today it’s back down to 3% of the overall population with no difference in the late breeders. It appears that the salmon that used to spawn later in the summer are being negatively affected by hotter water temperatures and are having less reproductive success. Natural selection seems to favor earlier spawning in cooler water, reducing genetic variability among the population.

Lastly, take a look at this spectacular (and kinda creepy) riverbed on China’s Mount Gongga. The unique red coloring comes from a new variety of algae that first appeared in 2005 and only grows on local rocks. More rocks have been exposed in recent years due to debris slides and human activity, allowing the algae to become widespread.