Svante Pääbo's lab at the Max Planck Institute for Evolutionary Anthropology in Germany has mastered the process of obtaining DNA from ancient bones. With the techniques in hand, the research group has set about obtaining samples from just about any bones they can find that come from the ancestors and relatives of modern humans. In their latest feat, they've obtained a genome from a human femur found in Siberia that dates from roughly the time of our species' earliest arrival there. The genome indicates that the individual it came from lived at a time where our interbreeding with Neanderthals was relatively recent, and Europeans and Asians hadn't yet split into distinct populations.
The femur comes from near the town of Ust’-Ishim in western Siberia. It eroded out of a riverbank that contains a mixture of bones, some from the time where the sediments were deposited (roughly 30-50,000 years ago), and some likely older that had been washed into the sediments from other sites. The femur shows features that are a mixture of those of paleolithic and modern humans, and lacks features that are typical of Neanderthal skeletons.
Two separate samples gave identical carbon radioisotope dates; after calibration to the 14C record, this places the bone at 45,000 years old, give or take a thousand years. That's roughly when modern humans first arrived in the region. That also turned out to be consistent with dates estimated by looking at the DNA sequence, which placed it at 49,000 years old (the 95 percent confidence interval was 30-65,000 years).
A new observation of the M82 galaxy has turned up a surprise—a previously discovered, incredibly bright object. was pulsing The object, called M82 X-2, is bright enough to be classified as an ultra-luminous X-ray source, or ULX. It sits close to its previously discovered sibling, M82 X-1, near the core of M82. The discovery, which was made by NASA’s NuSTAR (Nuclear Spectroscopic Telescope Array) and the Chandra X-ray Observatory, has provided new clues about the nature of that mysterious class of objects.
X-2 turns out to be the brightest pulsar ever discovered—so bright that it challenges current models of how pulsars work.
NuSTAR had initially been pointed toward M82 in the hope of observing a new supernova, and the team of researchers had no idea that they would happen upon this strange behavior in an ULX. To clarify which source was producing the pulsations, the Chandra X-ray Observatory observed the region, successfully separating X-2 from the noise.
Today, a team of Polish researchers is reporting that it has re-established sensation and limited movements in a previously paralyzed patient. The technique involved both the transplantation of nerve fibers from the leg and a suspension of support cells obtained from the olfactory area of the brain. The results, while striking, only apply to a single patient; more work will need to be done to determine if the approach can work generally.
Spinal cord injuries are notoriously difficult to heal. Although there are nerve cells throughout the spinal cord, the majority of its function is performed by the long axons that extend up and down the length of the body. The axons transmit sensory signals to the brain and receive muscle commands back.
Injuries to the spinal cord sever these connections. The injured region generally forms a thick scar that inhibits the regrowth of axons, leaving regions below that point permanently severed from the brain. The result is paralysis and a lack of sensation. Attempts at therapies have focused on overcoming the effect of this scar. While we've learned a lot about the inhibition of nerve growth, what we've learned has not resulted in any significant successes.
A Utah man was sentenced to a year probation, half of which must be served under house arrest, and fined $15,000 Monday after pleading guilty to stealing a fossilized dinosaur footprint believed to be 190 million years old.Grand County Sheriff's Office The defendant, Jared Ehlers, 35, said he was "sorry" for unhinging the 150-pound sandstone slab in the Sand Flats Recreation Area of Southeastern Utah and dumping the three-toed print into the Colorado River.
"I don't have a lot to say," Ehlers said during sentencing before US District Judge Dale Kimball. "I'm just extremely sorry for a horrible decision that I made."
While on the Hell's Revenge trail, Ehlers saw that the footprint was loose. He pried it up and took it to his nearby Moab home. Federal authorities said he dumped the print after being questioned about the print. He pleaded guilty in July to a felony count of theft of a paleontological resource. [PDF]
Geology rewards an active imagination. It gives us a lot of tantalizing clues about very different times and places in Earth’s history, leaving us to try to answer “Man, what would that be like?” One of the things that's tough to imagine involves changing something that most of us never give a second thought—the fact that compasses point north. That’s plainly true today, but it hasn’t always been.
What we call the “north” magnetic pole—the object of your compass’ affection—doesn’t need to be located in the Arctic (it noticeably wanders there, by the way). It feels equally at home in the Antarctic. The geologic record tells us that the north and south magnetic poles frequently trade places. In fact, the signal of this magnetic flip-flopping recorded in the seafloor was the final key to the discovery of plate tectonics, as it let us see how ocean crust forms and moves over time.
That the poles flip is interesting in itself, but “Man, what would that be like?” Does the magnetic pole slowly walk along the curve of the Earth over thousands of years, meaning your compass might have pointed to some part of the equator for long stretches of time? Do the poles weaken to nothing, disappearing for a while before re-emerging in the new configuration? Do they somehow flip in the blink of an eye? Given the number of species that use the Earth’s magnetic field to navigate—especially for seasonal migrations—this is more than an academic curiosity.