- Size and Strength Not a Mate-Choice Factor for Everyone
- Civilian Supercomputer Shatters Nuke Simulator’s Speed Record
- Birth of a New Species Witnessed by Scientists
- Titanic Thirty Meter Telescope Will See Deep Space More Clearly
Posted: 16 Nov 2009 01:46 PM PST
Unlike most Western guys and gals looking for love, Africa's Hadza foragers pair up without regard to each other's size and strength, a new study finds. And that stature-may-care approach underscores the often unappreciated variety of human mating strategies, the researchers say.
Hadza marriages don't tend to consist of individuals with similar heights, weights, body mass indexes, body-fat percentages or grip strengths, say behavioral ecologist Rebecca Sear of the London School of Economics and anthropologist Frank Marlowe of Florida State University in Tallahassee. Neither do Hadza couples feature a disproportionate percentage of husbands taller than their wives, as has been documented in some Western nations, the researchers report in the October 23 Biology Letters.
Almost no Hadza individuals mention height or size when asked to explain what makes for an attractive mate, Sear and Marlowe add.
People everywhere seek healthy, fertile marriage partners, Sear proposes. "But I suspect there may not be a preference for one particular signal of health in mates across every population," she says.
Among the roughly 1,000 Hadza scraping out a living in rural Tanzania, knowledge of a potential mate's health history may render that person's height and weight irrelevant, the researchers suggest. Also, any health benefits of being big may get nullified by the difficulty of maintaining a large body during periodic food shortages endured by the Hadza.
Sear and Marlowe criticize evolutionary psychologists who have argued that physical size influences mating decisions in all societies. That argument rests largely on self-reports of Western college students and analyses of personal advertisements in U.S. newspapers for dating partners, they say.
Other researchers suspect that cultural evolution over the past 50,000 years, not genetic evolution during the Stone Age, has allowed human mating strategies to become increasingly diverse (SN: 5/23/09, p. 5).
"Cross-cultural data are hard to come by, and this is a valuable contribution," comments psychologist Robert Kurzban of the University of Pennsylvania in Philadelphia. But he argues that the Hadza findings do fit with evolutionary psychologists' proposal that genetically ingrained, universal mating strategies get triggered in different ways depending on social and ecological conditions.
In large societies, where people know little about one another's health history and food is plentiful, height and weight may be reasonable initial indicators of a healthy mate, he suggests.
But increasing familiarity with a romantic partner breeds a more discriminating eye, remarks anthropologist Boguslaw Pawlowski of the Polish Academy of Sciences in Wroclaw.
Sear and Marlowe analyzed evidence for mating based on size and strength in 185 to 236 Hadza couples, the number of couples depending on the particular measure. A team led by Marlowe gathered this evidence from 2001 to 2006. Nearly all couples who were married during that period participated in the study.
Among the Hadza, women marry at around age 18 and men at age 20. After a sexual liaison, a couple will begin sleeping at the same hearth and is considered married. Only a small minority of men have more than one wife. Divorce is common, though, and most people get married many times.
In 8.2 percent of Hadza marriages, the wife was taller than the husband. That's no different than the frequency of female-taller marriages expected to occur by chance, Sear says. In a 2006 investigation, she also found a random-chance level of female-taller marriages in an African farming community.
In contrast, the proportion of female-taller marriages in England is substantially lower than expected by chance, signaling a male-taller preference, she says.
Images: Wikimedia Commons/Idobi
Posted: 16 Nov 2009 01:14 PM PST
The retooled Jaguar supercomputer blew away the competition on the latest list of the 500 fastest computers in the world, clocking an incredible 1.759 petaflops — 1,759 trillion calculations per second.
The machine, housed at the Department of Energy's Oak Ridge National Laboratory in Tennessee, added two more cores with the aid of almost $20 million in stimulus spending. With the new processors, the Cray XT5 plowed past the Top500 competition. It's more than 69 percent faster than the previous record holder, Los Alamos National Laboratory's IBM Roadrunner, and is more than twice as powerful as the third-fastest computer on the list.
But it's not just how many calculations the machine performs that's noteworthy. The new supercomputer also marks a turning point in the placement for funding of America's computing resources.
Jaguar's spot atop the list marks the first time a civilian Department of Energy computer has been the most powerful in the world. Instead of modeling nuclear explosions, which is Roadrunner's primary job, Jaguar carries out scientific research on the globe's climate and other computational-intensive problems.
"Supercomputer modeling and simulation is changing the face of science and sharpening America's competitive edge," said Department of Energy Secretary Steven Chu. "Oak Ridge and other DOE national laboratories are helping address major energy and climate challenges and lead America toward a clean energy future."
The Department of Energy has long been a chimera of different research components. The DOE was created out of the Energy Research and Development Agency in the late 1970s, which was itself formed largely out of the Atomic Energy Commission in 1974. The AEC managed the national laboratory system that developed during the Manhattan Project and was responsible for both civilian and military nuclear research.
Built on this strange mix and shaped by the '70s energy crises, the agency's roles managing nuclear weapons and civilian energy research have shared the same slice of the federal budget— and defense spending, or civilian research with military applications, tended to receive the lion's share of that slice.
In recent years, research into clean energy has received increasing support, a trend which has accelerated under new secretary, Steven Chu, who has directed much of the stimulus spending into developing new energy technologies. The appearance of a civilian DOE computer in the top spot on the supercomputer list is a sign of the times.
It should be noted, though, that the split between military and civilian supercomputers hasn't been hard and fast. Supercomputers built to study nuclear explosions have long allocated spare computing time for other types of science.
What's special about Jaguar is that it's operated entirely within the DOE's Office of Science, so civilian science gets priority for the one billion processor hours that the machine can offer.
Jaguar is operated by the National Center for Computational Sciences, which is headed by James Hack, a climate modeler by training. He said Jaguar's upgrades allow for progressively better climate models, continuing a trend that's been at work for decades.
"From the early 80s it may be close to a million fold improvement in computational performance," Hack said.
Back then, climate models had to break up the earth's surface into chunks with an area of 3,900 square miles. Now, they can run simulations where each unit is just 10 to 20 square miles. In the old models, Lake Erie would have been two or three boxes. Now, it could be represented by more than 1,000 individual units that can more accurately reflect local conditions.
All that resolution is increasing the accuracy of the simulations. In July, a model run on the supercomputer became the first to accurately depict an abrupt climate change in the past.
"The speed and power of petascale computing enables researchers to explore increased complexity in dynamic systems," Hack said in a press release.
In the Moore's Law driven world of supercomputing, Jaguar — at least in its current incarnation — is not likely to lead the list for long. Several plans are afoot for computers that will carry out tens of petaflops that could be running in just a few years.
Image: A very high-resolution model of carbon flux as dawn breaks across the United States. The green represents carbon uptake, while the red shows carbon outflow/ORNL. Video: Climate model run on Jaguar.
Posted: 16 Nov 2009 12:00 PM PST
On one of the Galapagos islands whose finches shaped the theories of a young Charles Darwin, biologists have witnessed that elusive moment when a single species splits in two.
In many ways, the split followed predictable patterns, requiring a hybrid newcomer who'd already taken baby steps down a new evolutionary path. But playing an unexpected part was chance, and the newcomer's singing his own special song.
This miniature evolutionary saga is described in a paper published Monday in the Proceedings of the National Academy of Sciences, and authored by Peter and Rosemary Grant, a husband-and-wife team who have spent much of the last 36 years studying a group of bird species known collectively as Darwin's finches.
The finches — or, technically, tanagers — have adapted to the conditions of each island in the Galapagos, and provided Darwin with a clear snapshot of evolutionary divergence when he sailed there on the HMS Beagle. The Grants have pushed that work further, with decades of painstaking observations providing a real-time record of evolution in action. In the PNAS paper, they describe something Darwin could only have dreamed of watching: the birth of a new species.
The species' forefather was a medium ground finch, or Geospiza fortis, who flew from a neighboring island to the Grants' island of Daphne Major, and into their nets, in 1981. He "was unusually large, especially in beak width, sang an unusual song" and had a few gene variants that could be traced to another finch species, they wrote. This exotic stranger soon found a mate, who also happened to have a few hybrid genes. The happy couple had five sons.
In the tradition of finches, for whom songs are passed from father to son and used to serenade potential mates, the sons learned their immigrant father's tunes. But their father's vocalizations were strange: he'd tried to mimick the natives, but accidentally introduced new notes and inflections, like a person who learns a song in a language they don't understand.
These tunes set the sons apart, as did their unusual size. Though they found mates, it may only have taken a couple generations for the new lineage to ignore — or be ignored by —local finches, and breed only with each other. The Grants couldn't tell for certain when this started,but they were certain after four generations, when a drought struck the island, killing all but a single brother and sister. They mated with each other, and their children did the same.
No exact rule exists for deciding when a group of animals constitutes a separate species. That question "is rarely if ever asked," as speciation isn't something that scientists have been fortunate enough to watch at the precise moment of divergence, except in bacteria and other simple creatures. But after at least three generations of reproductive isolation, the Grants felt comfortable in designating the new lineage as an incipient species.
The future of the species is far from certain. It's possible that they'll be out-competed by other finches on the island. Their initial gene pool may contains flaws that will be magnified with time. A chance disaster could wipe them out. The birds might even return to the fold of their parent species, and merge with them through interbreeding.
But whatever happens, their legacy will remain: New species can emerge very quickly — and sometimes all it takes is a song.
Images: 1) An example of Daphne Major's native medium ground finches on the left, and the original newcomer on the right. 2) Successive generations of the hybrids, which now mate only with each other.
Citation: "The secondary contact phase of allopatric speciation in Darwin's finches." By Peter R. Grant and B. Rosemary Grant. Proceedings of the National Academy of Sciences, Vol. 106, No. 46, November 16, 2009.
Posted: 16 Nov 2009 11:01 AM PST
SANTA CRUZ, California — Four hundred years after Galileo's telescope revolutionized humanity's view of the universe, a gigantic telescope is in the works that could take us to a new, deeper level of understanding.
The enormous Thirty Meter Telescope, with a primary mirror the size of a blue whale, is part of a new generation of super powerful ground-based telescopes. Scheduled for completion in 2018, it will have nine times the collecting power of the Keck telescopes and 12 times the resolution of the Hubble Space Telescope. From its recently selected location atop the volcanic dome of Mauna Kea in Hawaii, the pioneering telescope will provide an extremely detailed look at the universe.
"As we learn more, the cosmos become more mysterious and require more human ingenuity to get to the next step," Jerry Nelson, UC Santa Cruz physicist and TMT project scientist, said at a public talk Thursday.
Once finished, the new telescope will allow astronomers to see faint objects clearer than ever before. It will be able to focus on and indentify extremely distant structures that currently appear as blurry smudges in the Hubble Deep Field. As yet, no one knows what these objects are.
This new resolution will provide insights into the both dark matter and dark energy. And it will widen the search for planets orbiting stars outside our solar system. For the first time, we will be able to routinely image direct light from these exoplanets, garnering information on their atmospheric chemistry and dynamics.
The new TMT will also be able to see further back in time than any previous telescope, all the way back to the formation of the first stars and galaxies that followed the universe's "Dark Ages."
An adaptive optics system will aid the telescope's ability to see into deep space. Atmospheric turbulence usually distorts light coming from distant stars. So the adaptive optics system uses a sodium laser to probe current conditions, and information about the turbulence is fed into a small deformable mirror, which makes real-time corrections to the atmosphere's quivering. The effect is sort of like putting glasses on to correct for blurred vision — the end result is a much crisper image.
Without adaptive optics, ground-based astronomy couldn't compete with space-based projects such as Hubble. The system is considered so vital that Nelson refers to it as the "heart and soul of the mirror and telescope."
Nelson has been called the father of the modern telescope, because it was his innovative design in the 1970s that allowed for the creation of big telescopes like the 10-meter Keck. His segmented mirrors have completely transformed the field of astronomy, leading UC Santa Cruz astronomer Sandy Faber to call him a modern day Galileo.
Previously, telescope mirrors larger than 5 meters were considered unfeasible because of many problems: They were hard to cast, their supports were delicate and breakable, and they would warp under their own weight.
Nelson realized that segmenting the main mirror into separate hexagonal pieces could solve all these problems. His design positioned the individual mirrors in a honeycomb-like arrangement and used an intricate computer guidance system to make them act as one, larger unit.
The first telescope to take advantage of this new plan was Keck, which has main mirrors composed of 36 individual pieces. The reflector on the Thirty Meter Telescope will be an order of magnitude leap above this with 492 small mirrors.
Telescopes have doubled in size every 30 years over the last century, and in the not-too-distant future, Nelson predicts we will see 50- and even 100-meter telescopes.
This is not to say that such undertakings will be easy. At an estimated cost of $970 million, the TMT will require an international consortium that includes the University of California system, Caltech, Canada, and Japan. Further funding will come from the Gordon and Betty Moore Foundation, which committed $200 million to the project.
"The discoveries we're going to make from TMT will simply increase our thirst for even bigger telescopes with even greater capabilities," says Nelson. "So as long as we retain our curiosity and have the wealth to build these kinds of things, I think we're going to see bigger things."
Images: TMT Observatory Corporation
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