New Atomic Jigsaw Decipherer Proves Ancientness of Aussie Rock

A timeline of the history of our planet places the formation of the Jack Hills zircon and a "cool early Earth" at 4.4 billion years.

A timeline of the history of our planet places the formation of the Jack Hills zircon and a “cool early Earth” at 4.4 billion years.

Imagine you’re digging around your back yard—perhaps making a nice herb garden or digging posts for a deck—and you come across a rock along the way. That’s not too hard to imagine, since either of those activities are bound to turn up a large number of rocks, but perhaps you’re more prone to couch surfing than home improvement.

In any event, you find a rock.

Ever wonder how old that rock might be? Where it might have traveled? Perhaps, for example, it had been stepped on by a dinosaur once upon a time?

These musings become even more interesting if you happen to live in western Australia, particularly in the Jack Hills region. On the outcrops of that sparsely inhabited region of land, you might just come across tiny bits of rock that date back to a few hundred million years after the Earth was first formed. We’re talking rocks that are 4.4 billion years old.

That’s right, billion. With a B.

4,400,000,000.

How do geologists come up with this number? Well, rather than relying on made-up texts, researchers look to the ratios of certain isotopes contained within the sample.

Remember if you will that an isotope is an atom of an element—defined by that atom’s number of protons—that has a varying number of neutrons. For example, the most abundant form of carbon on Earth has eight protons and eight neutrons, but there are also forms of carbon found on earth that have eight protons and seven or six neutrons.

When you get to really disparate numbers–like eight protons and two neutrons, for example–the atom becomes unstable. A proton might spontaneously turn into a neutron to even out the ratio, giving off bits of energy in the process.

That energy is also known as radiation.

This 4.4 billion-year-old zircon crystal is providing new insight into how the Earth cooled from a ball of magma and formed continents much earlier than previously believed.

This 4.4 billion-year-old zircon crystal is providing new insight into how the Earth cooled from a ball of magma and formed continents much earlier than previously believed.

 

Thanks to accelerators around the world that can create these unstable isotopes, scientists know which isotopes eventually turn into what stable atoms. They also know the likely paths they take to get there and how long it takes for this process to occur. So if you know how many original unstable isotopes there are, and you also know how many final stable atoms that have decayed there are, you can figure out how long its been since the sample had only the unstable isotopes—it’s first formation.

Researchers have done this with a few rare zircon rocks from the Jack Hills region, and discovered that the ratio of rare lead ions indicates that the rocks in question are at least 4.4 billion years old. But some people require more proof. What if the ratios got thrown off by atoms being added later in the rock’s life, for example?

John Valley, a geochemist from the University of Wisconsin, has given them this proof. He lead a study that used a new technique called atom-probe tomography that actually maps and weighs the individual atoms in a microscopic sample of zircon. By checking out again the ratio of isotopes and determining their location within the crystalline structure of the zircon, Valley was able to corroborate the earlier findings that the rock comes from 4.4 billion years ago.

But that’s not the end of the story.

Rather than being randomly distributed throughout the sample, the lead isotopes were clustered together like raisins in a pudding. The clusters of lead atoms formed 1 billion years after crystallization of the zircon, by which time the radioactive decay of uranium had formed the lead atoms that then diffused into clusters during reheating.

“The zircon formed 4.4 billion years ago, and at 3.4 billion years, all the lead that existed at that time was concentrated in these hotspots,” Valley says. “This allows us to read a new page of the thermal history recorded by these tiny zircon time capsules.”

The study, according to Valley, strengthens the theory of a “cool early Earth,” where temperatures were low enough for liquid water, oceans and a hydrosphere not long after the planet’s crust congealed from a sea of molten rock.

“The study reinforces our conclusion that Earth had a hydrosphere before 4.3 billion years ago,” and possibly life not long after, says Valley.

“The Earth was assembled from a lot of heterogeneous material from the solar system,” Valley explains, noting that the early Earth experienced intense bombardment by meteors, including a collision with a Mars-sized object about 4.5 billion years ago “that formed our moon, and melted and homogenized the Earth. Our samples formed after the magma oceans cooled and prove that these events were very early.”

The study, “Hadean age for a post-magma-ocean zircon confirmed by atom-probe tomography,” was published by Valley and a whole host of associates from the University of Wisconsin; the University of Puerto Rico; CAMECA in Madison, Wisconsin; Curtin University of Western Australia; and the University of Western Ontario.

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Hocking a Loogie’s Power Potential

spitting-fountainScience has not yet, unfortunately, discovered Mr. Fusion. The coffee-maker-sized cold fusion power generator that runs on garbage would not only be able to power a time-warping DeLorean, it would solve all of the world’s energy needs in a single “Great Scots!”

That doesn’t mean that, however, that scientists aren’t working on some pretty interesting energy harvesting gadgets. Take this one example from Penn State that uses your loogies for power.

Yes, you read that right. Loogies aren’t just for grossing out your siblings anymore.

The idea of microbial fuel cells have been around a long time. You basically introduce a lot of organic material to a bunch of hungry bacteria, which produce energy while they chomp on the meal. Researchers typically turn to wastewater for the organic material fule, but guess what? Your saliva has plenty of it swimming around too.

Of course, a person isn’t going to produce even a gallon of saliva very quickly, so the energy generator we’re talking about here is proportionally small. In a report in a recent issue of Nature Publishing Group’s Asia Materials, environmental engineering professor Bruce Logan and fellow researcher Justine Mink demonstrate a micro-sized microbial fuel cell that can produce minute amounts of energy–enough to run tiny microchips.

While the single microwatt of power they can produce is tiny, the range of potential applications is vast.

The researchers believe that the emergence of ultra-low-power chip-level biomedical electronics, devices able to operate at sub-microwatt power outputs, is becoming a reality. One possible application would be a tiny ovulation predictor based on the conductivity of a woman’s saliva, which changes five days before ovulation. The device would measure the conductivity of the saliva and then use the saliva for power to send the reading to a nearby cell phone.

Or imagine a blood-sugar-level sensor that is powered by a diabetic’s own spit. Or a heart-rate monitor that gets charged by your stinky sweat while you work out.

This stuff is heavy.

The paper, “Energy harvesting from organic liquids in micro-sized microbial fuel cells,” was published by Mink and Logan, along with Ramy Quaisi and Muhammad Hussain from the Integrated Nanotechnology Lab at King Abdullah University of Science and Technology in Thuwal, Saudi Arabia.

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Giant Human Brain Sucks Energy, Stunts Growth for Years

2570892-sbigbrainHave you ever noticed that it’s kind of hard to guess the age of a toddler until they open their mouths and speak? I’ve got a behemoth of a nephew who could have passed for four at age two based on size alone. But at the same time, he was a bit late to the language game, and could potentially have been mistaken for a younger age around his fourth birthday (at least, if he hadn’t been such a behemoth).

There’s a good reason for this, according to a new study from Northwestern University. A human child’s physical growth slows to a snail’s pace between the ages of two and five. That’s why it’s so hard to guess age based on size at that time. So where is all of that energy going to?

Straight to their noggins.

After analyzing a pool of existing PET and MRI brain scan data–which measure glucose uptake and brain volume, respectively–Christopher Kuzawa, professor of anthropology at Northwestern, found that a toddler’s brain sucks up a staggering 66 percent of the energy normally consumed by the entire body at rest. That’s more than 40 percent of a kid’s total energy expenditure during the day.

It’s at this age where a person’s brain soaks in the most information, busily pruning synapses and strengthening connections based on learning and experience. And with the brain soaking up that much energy, there isn’t really any left to fuel physical growth.

It was previously believed that the brain’s resource burden on the body was largest at birth, when the size of the brain relative to the body is greatest. The researchers found instead that the brain maxes out its glucose use at age five.

“At its peak in childhood, the brain burns through two-thirds of the calories the entire body uses at rest, much more than other primate species,” said William Leonard, professor and chair of Northwestern’s Department of Anthropology. “To compensate for these heavy energy demands of our big brains, children grow more slowly and are less physically active during this age range. Our findings strongly suggest that humans evolved to grow slowly during this time in order to free up fuel for our expensive, busy childhood brains.”

The paper, “Metabolic costs and evolutionary implications of human brain development,” was published in the Proceedings of the National Academy of Sciences by Kuzawa and Leonard as well as Harry T. Chugani, Lawrence I. Grossman, Leonard Lipovich, Otto Muzik, Patrick R. Hof, Derek E. Wildman, Chet C. Sherwood and Nicholas Lange.

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Pygmy Populations Wear Different Brands of the Same Clothes to Life’s Evolutionary Party

Batwa young woman and child

A Batwa woman and her child in Bwindi Impenetrable Forest National Park, Uganda. Image: Photo courtesy of George Perry/Penn State

All over the animal kingdom you see amazing examples of creatures that are exquisitely adapted to their environments. From Darwin’s finches with differently shaped beaks to reach slightly different foods to a newly found mouse that can stand up to mankind’s worst rodenticides, life always finds a way to make the most of its surroundings.

One species of animal that doesn’t usually cross my mind, however, is human beings. I can think of a few adaptations – color of skin to withstand the sun’s heat or the digestive power to break down lactose in northern territories with fewer protein options – but for the most part it seems that we’re all basically the same.

Then again, I don’t usually get out of the country much.

Deep in the rain forests of the world exist a human phenotype that you don’t run across very often – the short pygmy population. Now here’s an awesome example of adaptation. The short stature and small overall body size reduces the amount of food needed survival, which is important in an area where calories are hard to come by outside of fruit season. Their size also reduces the amount of heat their body generates – another important advantage in the sweltering climate – and allows them to climb trees and navigate dense foliage.

What’s really fascinating, I think, is that this phenotype has arisen many separate times by mutating many separate genes. At least, that’s the word from a new genetic study from Penn State University.

George Perry, assistant professor of anthropology and biology,  compared 16 different genetic locations associated with short stature in the genomes of four different pygmy populations in Batwa and Uganda. Together, their average height for men is five feet and a mere four foot eight for women. But while their shortness is shared, how they come by that adaptation is not.

Different groups of pygmy populations have different genetic mutations that have adapted them to life in the rain forest. This is what’s known as convergent evolution – where different populations show up to the same evolutionary party wearing the same clothing but from different brands. I’ve heard a lot of examples over the years from the animal kingdom, but never before in humans.

And I find that fascinating.

The study, “Adaptive, convergent origins of the pygmy phenotype in African rainforest hunter-gatherers,” was published in the Proceedings of the National Academy of Sciences by Perry along with Luis B. Barreiro, Sainte-Justine Hospital Research Centre and University of Montreal; Matthieu Foll, Ecole Polytechnique Fédérale de Lausanne and Swish Institute of Bioinformatics; Jean-Christophe Grenier, Department of pathology, Sainte-Justine Hospital Research Centre, Canada; Etienne Patin and Lluis Quintana-Murci, Institut Pasteur and Centre National De La Recherche Scientifique, France; Yohan Nédélec and Alain Pacis, Sainte-Justine Hospital Research Centre and University of Montreal; Maxime Barakatt and Simon Gravel, McGill University; Xiang Zhou, University of Chicago; Sam Nsobya, Makerere University, Uganda; Laurent Excoffier, University of Bern and Swiss Institute of Bioinformatics; and Nathaniel J. Dominy, Dartmouth College.

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Why Science Says Don’t Pee in the Pool

pee_pool_6558Okay, I admit it. I’ve peed in the pool before. It seems like such an innocuous act. How much is my pint of urine really going to affect the thousands of gallons of continually treated water in a standard swimming pool? I mean, as I’m always fond of pointing out, urine is sterile when it leaves the body. What’s the harm?

According to a new study from Purdue University, there could actually be quite a lot.

It all comes down to chemical reactions. Most all pool water is pretty heavily chlorinated to keep bacteria and other microorganisms from proliferating. When you introduce urine to chlorine, however, it tends to make uric acid. And uric acid, it turns out, tends to make a lot of cyanogen chloride and trichloramine, both of which are problems.

Cyanogen chloride is a toxic compound that affects many organs, including the lungs, heart and central nervous system by inhalation. Trichloramine has been associated with acute lung injury in accidental, occupational or recreational exposures to chlorine-based disinfectants.

Definitely problems.

So when you add up a slightly smaller public swimming pool in an indoor enclosed space with a whole bunch of people who don’t see the harm in peeing in the pool, there’s definitely a chance that these chemicals can build up, get released in to the air and make people sick.

Places not to pee now include:

  1. On the electric fence
  2. In the swimming pool

On another note, dealing with subjects like urination always brings out the best quotes from academics. For example:

  • Researchers are advising swimmers to observe “improved hygiene habits.”
  • …given that uric acid introduction to pools is attributable to urination, a voluntary action for most swimmers…
  • A common misconception within the swimming community is that urination in pools is an acceptable practice, although signs and placards are posted in many pools to encourage proper hygiene.

The study, “Volatile Disinfection Byproducts Resulting from Chlorination of Uric Acid: Implications for Swimming Pools,” was published in Environmental Science and Technology by Jing Li, a visiting scholar from the China Agricultural University working at Purdue University with Ernest R. Blatchley III, a professor of civil engineering at Purdue.

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Yet Another Study Linking Exercise with Mental Capacity

leonardoSound mind, sound body—the mantra of the ancient Greeks—continue to appear to be right on target. Previous studies have suggested that children with higher levels of aerobic fitness show greater brain volumes of gray matter, the outer surface tissue of the brain important for memory and learning. They’ve also shown a relationship between fitness and the integrity of white matter—the interior neural connectors wiring the grey matter together—in older adults.

And now, a new study from the University of Illinois has made the same connection for white matter in children, which sort of makes sense. The brain continues developing well into most people’s 20s, so it would stand to reason if physical fitness affects the brain, it’d have the same impact, if not a greater one, on a developing brain.

The Illinois team looked at five white-matter tracts in the brains of 24 participants using a technique called diffusion tensor imaging, or DTI. DIT analyzes water diffusion into tissues, and for white matter, less diffusion means the tissue is more fibrous and compact.

And you want your neurons to be fibrous and compact.

After controlling for variables like socioeconomic status, the timing of puberty, IQ, or diagnosis of ADHD or other potential neural pitfalls, the study revealed significant fitness-related differences in the integrity of several white-matter tracts. These included the corpus callosum, which connects the brain’s left and right hemispheres; the superior longitudinal fasciculus, a pair of structures that connect the frontal and parietal lobes; and the superior corona radiata, which connect the cerebral cortex to the brain stem.

Yes, those are all pretty important, especially to attention and memory.

Of course, this is just one study and it only looked at a very small handful of kids, probably all from the same town. For any findings to grab any real support, they must be replicated time and again for a large number of subjects.

So they’re working on it.

The team is now two years into a five-year randomized, controlled trial to determine whether white-matter tract integrity improves in children who begin a new physical fitness routine and maintain it over time. The researchers are looking for changes in aerobic fitness, brain structure and function, and genetic regulation.

“Prior work from our laboratories has demonstrated both short- and long-term differences in the relation of aerobic fitness to brain health and cognition,” said Charles Hillman, kinesiology and community health professor at Illinois. “However, our current randomized, controlled trial should provide the most comprehensive assessment of this relationship to date.”

Just another reason to get your kids off their collective asses.

The study, “Aerobic fitness is associated with greater white matter integrity in children,” was published in Frontiers of Human Neuroscience by Hillman along with University of Illinois postdoctoral researcher Laura Chaddock-Heyman and Beckman Institute director Arthur Kramer.

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Up All Night to Get Lucky Proven Statistically

51d824aee8086The early bird may get the worm, but the night owl gets laid. At least, that’s the conclusion of Dario Maestripieri, a professor of comparative human development at the University of Chicago. And he has the statistics to back it up.

In a previous study, Maestripieri surveyed more than 500 graduate students from the University of Chicago Booth school of Business to assess financial risk aversion among male and female students. It showed that those prowling the night had higher levels of acceptable risk financially. It also asked about their sleep patterns and other behavioral tendencies.

He had all the info he needed right there, so why not run the numbers? Maybe those risk-taking tendencies extend beyond the financial realm?

“Night owls, both males and females, are more likely to be single or in short-term romantic relationships versus long-term relationships, when compared to early birds,” Maestripieri said. “In addition, male night owls reported twice as many sexual partners than male early birds.”

You hear that? Twice as many.

Maestripieri goes on to say that sleep tendencies can be influenced by genetic and hormonal characteristics, and that female night owls had higher levels of cortisol, which may be one of the biological mechanisms explaining the higher risk behavior.

Or it’s just common sense.

You know who is staying out late and partying all night? Drunk single people who are out for a good time. You know who’s not? People in committed relationships with a dog or a kid at home to take care of.

The study, “Night owl women are similar to men in their relationship orientation, risk-taking propensities, and cortisol levels: Implications for the adaptive significance and evolution of eveningness,” was published by Maestripieri in the journal Evolutionary Psychology.

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