African Fossils Push Back Origins Of Humans, and Other Stories

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After reevaluating the dates of a set of early human fossils, scientists have concluded that humans emerged as a species nearly 30,000 years earlier than once believed.

African Fossils Push Back Origins Of Humans


After reevaluating the dates of a set of early human fossils, scientistshave concluded that humans emerged as a species nearly 30,000 years earlierthan once believed. The discovery strongly suggests that anatomically modernhumans evolved before our species migrated out of Africa. Known as Omo I andOmo II, the two partial skulls and assorted limb and pelvic bones wasunearthed just a few miles from one another in southern Ethiopia. Theirexact age has been in dispute ever since their discovery in 1967. Recently,geologists from Utah and Australia took a fresh approach to the task byanalyzing oyster shells found in surrounding sediment layers. The relativeamounts of uranium and thorium isotopes in the shells pushes back ourorigins to about 195,000 years ago. Some anthropologists believe the skullof Omo II looks slightly more primitive than Omo I. If true, these fossilsmay date back to a time when Homo sapiens was just starting to differentiatefrom other types of primitive hominids. The discovery was reported in thejournal Nature.


Magnetar Flashes The Milky Way


A blast of radiation so powerful it outshone all the other stars in ourgalaxy rippled through the Milky Way in late December. The explosion ofgamma rays lasted for less than a tenth of a second, but released moreenergy than our sun does in 100,000 to 200,000 years. The source of theflare was an exploded star just twelve miles wide made entirely of neutrons.Known as SGR 1806-20, it is one of about 10 known magnetars, neutron starswith unusually strong magnetic fields. It is located about 50,000light-years from Earth in the constellation Sagittarius. Scientists suspectthe December 27, 2004 flare occurred because the star's magnetic fieldssomehow became twisted. It released this pent-up energy in a singlecataclysmic pulse. Researchers were shocked that a magnetar could producesuch a forceful explosion. Amazingly, SGR 1806-20 did not blow itself up inthe process. The flare may help explain the origins of short gamma raybursts scientists have previously detected but failed to trace to anysource. The research will be published in upcoming issues of Nature andother scientific journals.


Dream Practice Improves Birdsongs


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Zebra finches, like many songbirds, don't hatch with perfected tunes.Instead, they learn their songs by practicing and listening to mature males.Now researchers have deduced that dreaming helps young male finches obtainspectacular song results. Sebastien Deregnaucourt of City University, NewYork, and colleagues observed young finches during daytime singing practiceand immediately after the birds had obtained a good night's sleep. In themorning, many sounded worse than when they went to bed--but birds thatregressed the most overnight also went on to become the best singers.Apparently, the same brain areas active during daytime singing are also busyas the birds sleep. For this reason, the researchers ascribe the birds'astonishing choral improvements to nocturnal singing practice. They reportin the journal Nature that the rustiest morning singers probably improvefastest because their brains are the most plastic. While asleep, these birdsdevelop a wider range of song variations in their sleep and therefore theirtunes sound further off kilter in the morning. But the same neuralflexibility that led them astray overnight also helped the birds mastersongs in the end.


Pharaohs Imported Black Gold


The Middle East's thriving petroleum business has unexpectedly ancientroots, according to a new study. Long before the combustion engine wasinvented, the ancient Egyptians traded far and wide to obtain tar for theirmummies. Oceanographer Mahlon Kennicutt II of Texas A&M University analyzedthe unique chemical fingerprint of tar samples found on various Egyptianmummies. He reports in the Journal of Geoarcheology that the adhesive globscame from sources hundreds of miles away, including the Gulf of Suez and theDead Sea in Israel. These distant origins indicate the ancient Egyptiansbartered for their tar with merchants who frequented trade routes still usedtoday. The tar was used like duct tape to seal mummies against the elements.And the remains of an ancient Egyptian glassworks suggests crude oil wasused as fuel. Interestingly, the word mummy also comes from tar; the Arabicword mumiya denotes a component of tar called bitumen.


Honey, It Sounds Like Breeding Season


To decide when to start a family, songbirds listen in on the twitterings oftheir neighbors. According to new research, just hearing the presence ofextra birds spurs zebra finches to breed with extra enthusiasm. Theresearchers played birdsong recordings to two colonies of zebra finches. Onecolony listened to its own sounds, while the second heard the songs of extrabirds blended into their own noises. The colony that heard more birds intheir flock laid eggs earlier in the season, produced larger eggs, and weremore likely to synchronize their clutches than the other colony. Thefindings provide the first evidence to support a 67-year-old theory aboutbreeding timing in bird colonies. Known as the Darling hypothesis, it positsthat birds find breeding safety in large numbers, because it reduces therisk of predation to each chick. Synchronizing egg laying helps lower thatrisk even further. In such optimal breeding conditions, it also pays toinvest more energy in the clutch and lay larger eggs. The findings arereported in the Proceedings of the Royal Society.


Termites Select Food Via Sound


Plenty of people have heard their favorite foods calling to them from acrossthe dinner table. Turns out termites listen to the echoes of their ownchomping to select their woody meals. The drywood termite, Cryptotermesdomesticus tends to prefer boring through smaller blocks of wood to largerlogs. Australian researchers had a sense that the house wreckers followedtheir ears. So they offered groups of termites two wooden pine blocks, one20 millimeters and the other 160 millimeters long, and then recorded thevibrations caused by the little pests' jaws. The scientists report in theProceedings of the National Academy of Sciences that the smaller blockresonated at a higher frequency of 7.2 kilohertz, while the larger blockechoed at the lower note of 2.8 kilohertz. The termites clearly preferredthe more petite meal. The behavior likely helps the termites avoidcompetition from wood borers who turn up their noses at tinier blocks ofwood. Scientists hope to use the findings to develop new termite controlmethods.


Related Links:


African Fossils Push Back Origins Of Humans: Los Angeles Times / Scientific American / CNN (Associated Press)
Magnetar Flashes The Milky Way: New York Times / BBC
Dream Practice Improves Birdsongs: BBC
Pharaohs Imported Black Gold: Discovery.com
Honey, It Sounds Like Breeding Season: This email address is being protected from spambots. You need JavaScript enabled to view it. / The Guardian
Termites Select Food Via Sound: This email address is being protected from spambots. You need JavaScript enabled to view it.


Source: California Academy of Sciences