December 12, 2013 9:31 am
The desert tortoise, a hardy resident of the U.S. Southwest, may have met its match in climate change, authors of a new paper write. Unlike creatures such as insects, rodents or birds, tortoises display “impressive longevity,” the authors write. Their slow development and long lifespan, however, makes it difficult to conduct studies on how environmental conditions such as climate change may or may not impact their ability to thrive. The study’s results, unfortunately, don’t bode well for these long-lived desert dwellers. According to the long-term study, under future climate model predictions, the survival of this threatened species looks pretty iffy in its increasingly hostile, dry desert environment.
The researchers got an early start on collecting their data: starting in 1978, they began to monitor threatened Agassiz’s desert tortoises living in a 1-square mile plot just Joshua Tree National Park in California. Throughout the years, they would check up on the tortoises, using the method of capture-mark-recapture to see which individuals had passed on and which were still around. In 2012, they decided it was at last time to analyze their results and see how the tortoises had fared over the years.
From 1978 until 1996, they found, things were looking pretty good for the tortoises. Their population was high and stable. But from 1997 onward, things took a downward turn when a drought began and continued until 2002. Many turtles died, and populations began to shrink. According to computer models, mortality coincided with lack of rain in the winter.
After 2002, the population never fully recovered. Those that perished likely experienced very unpleasant final days, as the team writes, “The postures and positions of a majority of dead tortoises found in 2012 were consistent with death by dehydration and starvation.” Those that hadn’t succumbed to death by drought appeared to have been predated on by coyotes–which usually eat mammals–leading the team to fear that those carnivores are now developing a taste for turtle flesh under the more stressful environmental circumstances.
The conclusions are pretty dire: “If drought duration and frequency increase, they will likely have wider and more significant impacts on Agassiz’s desert tortoise survivorship, particularly in the low Sonoran Desert portion of their range in California, and it will be difficult or impossible for resource managers to mitigate their effects.”
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December 11, 2013 1:44 pm
There’s a lot of pressure on pregnant and and trying-to-get-pregnant women to do the right things: get the right vitamins, eat the right diet, restrain from the right vices at just the right time. But just as dads are taking on larger roles in the home, there is a growing body of research that suggests that men should be paying attention to their habits in the run-up to pregnancy, too—that males’ choices can also affect a child’s biological development.
A man who is obese, who smokes or drinks or who is exposed to toxic industrial chemicals can affect pregnancy rates and child development. And a new study shows that, at least in mice (which are pretty similar to humans for stuff like this), nutrient shortages in fathers can affect the rate of birth defects in their babies.
In an experiment where some male mice were fed a diet without enough folate, scientists found that their babies were more prone to birth defects. Sarah Kimmins, one of the researchers behing the study, told the CBC:
There’s a perception that’s no longer true, that really needs to be challenged, that the father can do whatever he wants in terms of what he eats, what kind of lifestyle he lives, whether he takes drugs or not, and this isn’t going to affect whether he has a healthy child or not,” she said.
“Our research really shows that this isn’t the case — men really need to think carefully about the life they’re living because there is a potential for an impact on the offspring.
Most men who eat normal diets should have folate levels that are fine. But, if a man is malnourished, he may not be getting enough. Or, inversely, if a man is obese, it can affect how folate is processed, meaning that even if he has enough, it may not be doing its job properly.
The folate shortages matter, says the Los Angeles Times, because it affects the proper functioning of the male mouse’s sperm. “As a result, those fathers apparently pass along an embedded “environmental memory” that affects how the genetic code plays out for the baby both in the womb and during a lifetime.”
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December 11, 2013 12:57 pm
Next time you visit a museum, consider being more prudent with your camera. According to new research, people who snap more pictures actually remember less about the paintings and relics they viewed than those who were more discreet behind the lens.
Psychologist Linda Henkel found herself annoyed with museum visitors snapping photos of every statue, painting and old pot, and tourists walking up to the Grand Canyon only to pay more attention to their cameras than to the scenery. So she decided to test whether or not those camera-happy visitors were really getting anything out of the experience they seemed so eager to document. LiveScience describes how she did this:
For her first experiment, Henkel recruited 28 undergraduates for a tour at the university’s Bellarmine Museum of Art. Pausing in front of 30 objects, the students were randomly assigned simply to observe 15 artifacts and photograph the other 15.
In a second experiment, 46 undergraduates went on a similar tour of the museum that focused on 27 objects. These students were randomly assigned to look at nine objects, to photograph another nine and to take pictures of a specific detail like the head or feet of a statue on the remaining nine.
The following day, students completed a verbal and visual memory test about the objects they saw on their visit. When the students took photos, she found, they remembered the actual objects less well. There was an exception, however. People who took a zoomed, detailed shot of a particular detail on a certain artifact or artwork did indeed better remember the object as a whole.
She dubbed the memory loss phenomenon ”photo-taking impairment effect,” LiveScience reports, and thinks that this happens because people perhaps use cameras as a crutch for returning to and remembering things later—like taking visual notes—rather than paying attention to what is transpiring in the moment.
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December 11, 2013 12:23 pm
When it comes to climate change, carbon dioxide may get all the attention, but it’s not the only greenhouse gas. In fact, it’s not even the strongest, on a molecule-by-molecule basis—not by a long shot. The “greenhouse warming potential” of a gas is a measure of how good the gas is at trapping heat, crossed with how long it tends to hang around in the atmosphere. So while carbon dioxide gas has a greenhouse warming potential of 1, methane, or natural gas, has a potential of 34. In a new study, a team of researchers have reported the discovery of a gas that has one of the highest greenhouse warming potentials ever seen: 7,100.
The gas, perfluorotributylamine, or PFTBA, says the Guardian, has been “in use by the electrical industry since the mid-20th century.” PFTBA is produced in or imported into the U.S. at scales higher than a million pounds per year. No one knows how much of it escapes to the atmosphere. Because it’s a complex chemical with no natural analogue, say the scientists in their study, there are no biological sinks out there in the world waiting to pull it out of the atmosphere, like trees do to carbon dioxide. They think that PFTBA probably hangs out in the air for at least 500 years, before it its broken down by chemical reactions in the upper atmosphere
PFTBA, say the scientists, is the most efficient greenhouse gas they’ve ever seen, on a molecule-by-molecule basis. But, because other greenhouse gases stay in the atmosphere longer, some, like sulfur hexafluoride, have higher greenhouse warming potentials.
The scientists say that if the concentration of perfluorotributylamine measured in Toronto, where they did their research, was the same all over the world (a pretty big assumption), then at its current levels the gas would be responsible for trapping 0.00015 watts of energy for every square meter of the planet. By comparison, carbon dioxide is responsible for 1.56 watts per square meter. But even if PFTBA isn’t evenly distributed all over the planet, it could still be an important factor contributing to local warming.
What this really means is that carbon dioxide, produced by burning fossil fuels and other activities, is definitely still the dominant driver of global warming. But, we need to take care to not get tunnel vision because, if we’re not careful, there are these other, newer gases that could cause just as much trouble at much lower concentrations.
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December 11, 2013 9:40 am
It’s a common television crime drama scenario: a body is found with no identification. Perhaps it is charred or otherwise disfigured, reduced to bone. The first thing that the television detectives will probably do is call in a forensic anthropologist to identify the bones. After 28 minutes of tightly scripted action, the bad guy is apprehended, all thanks to the bone expert. Of course, real life doesn’t go that way. And it turns out that even forensic anthropologists have a hard time identifying people based on the shapes of their skulls. According to a recent study from North Carolina State University, only 56 percent of forensic anthropologists can correctly pair up two images of the same skull when given two profile images.
Being able to identify people based on their skulls is a key part of forensic anthropology. The problem is that no one has ever really tested how good we are at it.
“In a lot of cases, murder victims or the victims of disasters are from lower socioeconomic backgrounds and don’t have extensive dental records we can use to make a match,” Dr. Ann Ross said in the NC State University press release. “But those people may have been in car accidents or other incidents that led them to have their skulls X-rayed in emergency rooms or elsewhere. And those skull X-rays have often been used to make IDs. I’ve done it myself. But now we’ve tried to validate this technique, and our research shows that the shape of the skull isn’t enough to make a positive ID.”
This might seems crazy—how can someone whose job it is to identify skulls not be able to do so any better than about half the time? It turns out that the task at hand is really hard. To prove it, Matthew Shipman at NC State University made the quiz that these professionals took publicly available. How many can you guess?
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