Category: Australian National University

Have scientists rendered the final word on penis size?

On By A.P.In Adam Jones, Australia, Australian National University, Brian Mautz, College Station, Dr. Rajadhyaksha, Penis, Proceedings of the National Academy of Sciences, Science, ScienceNOW, Texas, Texas A&M UniversityLeave a comment

sn-penis

No man is an island, and it turns out neither is his penis. New research suggests that size does matter (sorry, guys), but the penis is only one (sometimes) small contributor to manly allure. A man’s overall attractiveness to a woman, researchers have found, depends in part on the trio of height, body shape, and penis size.

Although the assault of penis pill spam in your inbox might make you think that “bigger is better,” scientific research has returned mixed results. Some findings say that women prefer longer penises, others say they like wider ones, and still others report that size doesn’t matter at all.

Most of these studies had either asked women directly about their preferences or had them rate the attractiveness of different male figures that varied only in penis length. The penis doesn’t exist in a vacuum, though, and biologists led by Brian Mautz, who was then at the Australian National University in Acton, wondered how penis size interacts with other body traits that are usually considered attractive or manly.

Using data from a large study of Italian men, the researchers created 343 computer-generated male figures that varied in penis size, as well as in height and shoulder-to-hip ratio—traits that other research has linked to attractiveness and reproductive success. Mautz and colleagues turned the figures into short video clips and projected them, life-sized, onto a wall for viewing by 105 women. Each woman watched a random set of 53 figures and rated their attractiveness as potential sexual partners on a scale of 1 to 7.

“The first thing we found was that penis size influences male attractiveness,” Mautz says. “There’s a couple of caveats to that, and the first is that the relationship isn’t a straight line.” Rather than the attractiveness rating consistently improving with each jump in penis size, the team found what Mautz calls “an odd kink in the middle.” Attractiveness increased quickly until flaccid penis length reached 7.6 centimeters (about 3 inches) and then began to slow down, the team reports online today in the Proceedings of the National Academy of Sciences.

The reason, Mautz says, is that penis size isn’t the only thing that matters. It interacts with other traits, and its effect depends on whether those other traits are already attractive to begin with. If one of the model men was tall and had a masculine, V-shaped torso with broad shoulders and narrower hips, for example, he was considered more attractive than his shorter, stockier counterparts, regardless of penis size.

An increase in penis size was also a bigger benefit to attractiveness, and a smaller penis was less of a detriment, to the taller, fitter figures than it was to shorter or potato-shaped ones. For example, a model that was 185 cm tall (about 6 ft) with a 7-cm-long (about 3-in-long) penis got an average score for attractiveness. To get that same score, a model that was 170 cm (about 5’6″) needed a penis of about 11 cm (about 4.5 in) in length. Boost the taller guy’s penis by just about centimeter, and the shorter guy needs double that to keep up and get the same attractiveness score. After that, the shorter male pretty much can’t continue to compete. To really reap the benefits of a big penis, a guy needs to be attractive in the first place, Mautz says. If he isn’t, even the biggest penis in the world won’t do him that much good.

So have women been responsible for the male penis getting larger—at least over the course of evolution? That’s a distinct possibility, the researchers say. Women may have selected for larger penises because they’re linked to higher rates of female orgasm and sexual satisfaction, which may explain why the human penis is proportionally larger than those of our evolutionary cousins.

That size matters, and that it matters in the context of other traits, makes sense, because proportionate features are attractive, says Adam Jones, a biologist who studies sexual selection and mate choice at Texas A&M University in College Station and who was not involved in the work. But he cautions that projections on a wall are no substitute for real life. Just because a woman prefers a man with a large penis doesn’t mean that she’s going to find one. Outside the lab, there’s greater variation and more traits to consider, so penis size might not be as important. That’s good, Jones says, because hurdles like competition with other women and her own perceived attractiveness could place her with a man who comes up a little short.

http://news.sciencemag.org/sciencenow/2013/04/the-final-word-on-penis-size.html?ref=em

Thanks to Dr. Rajadhyaksha for bringing this to the attention of the It’s Interesting community.

Water in faults vaporizes during an earthquake, depositing gold

On By A.P.In Alpine Fault, Australia, Australian National University, Canberra, Dion Weatherley, Earthquake, flash vaporization, gold, Imperial College London, Jamie Wilkinson, Nature Geoscience, New Zealand, OurAmazingPlanet, quartz, Queensland, Richard Henley, Science, United Kingdom, University of QueenslandLeave a comment

gold-ed
The tyrannosaur of the minerals, this gold nugget in quartz weighs more than 70 ounces (2 kilograms).

Earthquakes have the Midas touch, a new study claims.

Water in faults vaporizes during an earthquake, depositing gold, according to a model published in the March 17 issue of the journal Nature Geoscience. The model provides a quantitative mechanism for the link between gold and quartz seen in many of the world’s gold deposits, said Dion Weatherley, a geophysicist at the University of Queensland in Australia and lead author of the study.

When an earthquake strikes, it moves along a rupture in the ground — a fracture called a fault. Big faults can have many small fractures along their length, connected by jogs that appear as rectangular voids. Water often lubricates faults, filling in fractures and jogs.

About 6 miles (10 kilometers) below the surface, under incredible temperatures and pressures, the water carries high concentrations of carbon dioxide, silica and economically attractive elements like gold.

During an earthquake, the fault jog suddenly opens wider. It’s like pulling the lid off a pressure cooker: The water inside the void instantly vaporizes, flashing to steam and forcing silica, which forms the mineral quartz, and gold out of the fluids and onto nearby surfaces, suggest Weatherley and co-author Richard Henley, of the Australian National University in Canberra.

While scientists have long suspected that sudden pressure drops could account for the link between giant gold deposits and ancient faults, the study takes this idea to the extreme, said Jamie Wilkinson, a geochemist at Imperial College London in the United Kingdom, who was not involved in the study.

“To me, it seems pretty plausible. It’s something that people would probably want to model either experimentally or numerically in a bit more detail to see if it would actually work,” Wilkinson told OurAmazingPlanet.

Previously, scientists suspected fluids would effervesce, bubbling like an opened soda bottle, during earthquakes or other pressure changes. This would line underground pockets with gold. Others suggested minerals would simply accumulate slowly over time.

Weatherley said the amount of gold left behind after an earthquake is tiny, because underground fluids carry at most only one part per million of the precious element. But an earthquake zone like New Zealand’s Alpine Fault, one of the world’s fastest, could build a mineable deposit in 100,000 years, he said.

Surprisingly, the quartz doesn’t even have time to crystallize, the study indicates. Instead, the mineral comes out of the fluid in the form of nanoparticles, perhaps even making a gel-like substance on the fracture walls. The quartz nanoparticles then crystallize over time.

Even earthquakes smaller than magnitude 4.0, which may rattle nerves but rarely cause damage, can trigger flash vaporization, the study finds.

“Given that small-magnitude earthquakes are exceptionally frequent in fault systems, this process may be the primary driver for the formation of economic gold deposits,” Weatherley told OurAmazingPlanet.

Quartz-linked gold has sourced some famous deposits, such as the placer gold that sparked the 19th-century California and Klondike gold rushes. Both deposits had eroded from quartz veins upstream. Placer gold consists of particles, flakes and nuggets mixed in with sand and gravel in stream and river beds. Prospectors traced the gravels back to their sources, where hard-rock mining continues today.

But earthquakes aren’t the only cataclysmic source of gold. Volcanoes and their underground plumbing are just as prolific, if not more so, at producing the precious metal. While Weatherley and Henley suggest that a similar process could take place under volcanoes, Wilkinson, who studies volcano-linked gold, said that’s not the case.

“Beneath volcanoes, most of the gold is not precipitated in faults that are active during earthquakes,” Wilkinson said. “It’s a very different mechanism.”

Understanding how gold forms helps companies prospect for new mines. “This new knowledge on gold-deposit formation mechanisms may assist future gold exploration efforts,” Weatherley said.

In their quest for gold, humans have pulled more than 188,000 tons (171,000 metric tons) of the metal from the ground, exhausting easily accessed sources, according to the World Gold Council, an industry group.

http://www.livescience.com/27953-earthquakes-make-gold.html