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Month: November 2012 (page 1 of 9)

11.30.2012

how old is the grand canyon

Image from yabbedoo travel & tech.

Conventional wisdom has it that the Grand Canyon was carved out by the Colorado some 6-7 million years ago.  Now, new chemical studies of the helium spectra of  Canyon rock are calling that wisdom into question claiming that the canyon is over 60 million years old. From Science News:

But the new study, reported online November 29 in Science, looks instead at the chemistry of rocks exposed throughout the canyon. Rocks get cooler as erosion strips away the material above them. That cooling is chemically preserved in several ways, including in helium within the mineral apatite.

“When the apatite is hot, the helium simply diffuses out of the crystal; when the apatite is cold, helium is completely retained,” says study leader Rebecca Flowers of the University of Colorado Boulder. “So by measuring the helium we are constraining when the rock went from hot to cold as it moved closer to the Earth’s surface, or as the Earth’s surface moved closer to the rock as the canyon was carved.”

Flowers and Kenneth Farley of Caltech looked at helium in apatite crystals throughout the canyon, including how the element was distributed within the crystals — which gives more clues as to whether the rock cooled slowly or quickly. The scientists concluded that some ancient river must have carved out a chasm roughly the shape and size of the Grand Canyon by around 70 million years ago.

Not everyone is convinced by the new findings, which build on earlier work from the same research team. Karl Karlstrom, a geologist at the University of New Mexico, says that there must have been canyons throughout the area 70 million years ago, but most geological evidence supports the modern canyon — what visitors see today when standing at the rim — appearing only in the last 5 million to 6 million years.

Also check the New York Times and Science for more.

11.29.2012

eating meat helped our brains evolve

From Christopher Wanjek in the Washington Post:

At the core of this research is the understanding that the modern human brain consumes 20 percent of the body’s energy at rest, twice that of other primates. Meat and cooked foods were needed to provide the necessary calorie boost to feed a growing brain.

One study, published last month in the Proceedings of the National Academy of Sciences, examined the brain size of several primates. For the most part, larger bodies have larger brains across species. Yet humans have exceptionally large, neuron-rich brains for our body size, while gorillas — three times as massive as humans — have smaller brains with one-third the neurons. Why?

The answer, it seems, is the gorillas’ raw, vegan diet (devoid of animal protein), which requires hours upon hours of eating to provide enough calories to support their mass.

Researchers from Brazil, led by Suzana Herculano-Houzel, a neuroscientist at the Federal University of Rio de Janeiro, calculated that adding neurons to the primate brain comes at a fixed cost of approximately six calories per billion neurons.

For gorillas to evolve a humanlike brain, they would need an additional 733 calories a day, which would require two more hours of feeding, the authors wrote. A gorilla already spends as much as 80 percent of the tropics’ 12 hours of daylight eating.

Tell your vegetarian friends to chew on that.

11.29.2012

why the mean girls are so pretty

Julie Beck reports in Popular Science:

The meanies aren’t necessarily more physically attractive than anyone else, they are just better at using what the study calls “adornments” (clothes, makeup and the like) to make themselves seem more appealing. The researchers, Nicholas Holtzman and Michael Strube at Washington University in St. Louis, had their subjects remove all makeup, pull long hair back into a ponytail and don a white T-shirt and grey sweatpants. They were rated on their attractiveness in this unadorned state, set loose to adorn themselves to their hearts’ content, and rated again. All three Dark Triad traits were associated with higher attractiveness inthe adorned state, when controlling for attractiveness in the unadorned state. So you can take some small comfort in knowing that mean people are just as ugly as the rest of us, they’re just better at fooling everyone into thinking they’re hot.

The study suggests a possible reason why these subjects were compelled to make themselves more attractive: “When people high in Dark Triad [i.e. mean] traits dress-up, they may experience greater increments in self-esteem or derive more satisfaction from the additional attention they receive, compelling them to continue dressing well.”

Also see Scientific American.

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