Scientists

To many, human-animal chimeras--animals that contain human cells--sound like the stuff of nightmares. If you can picture a frog with a human head, a monkey with human vocal chords or a dog with opposable thumbs, you can see why some people want to put the brakes on any sort of scientific experiment that mixes cells from different species. The reality of chimeras is much less dramatic: Picture instead a pig that produces human insulin or a mouse getting chemotherapy for its human cancer cells.

It has been 10 years since scientists sequenced the human genome and published the results. To celebrate that anniversary, the journal Science is publishing a series of reflections on the accomplishment -- and its importance on science today and in the future. The first musings appeared Thursday and included "vignettes" from the scientists who led the two teams that decoded the genome, Francis Collins and J. Craig Venter. Collins, now National Institutes of Health director, wrote glowingly about medical advances that have emerged from genome sequencing -- including the case of a 6-year-old boy whose inflammatory bowel disease may have been cured by scientists who sequenced his DNA and discovered a mutation that may have caused his symptoms.

MOSCOW -- Russian scientists declared Monday that they have found and established the composition of pieces of the meteor that exploded over the Chelyabinsk region last week, injuring hundreds of people and causing millions of dollars worth of damage. Over the weekend, 53 tiny pieces of dark porous material were collected near Chebarkul Lake, 60 miles west of Chelyabinsk, the regional center, officials said. The biggest of the finds was 7 millimeters long. The samples were without doubt meteorites, Viktor Grokhovsky, a member of the Russian Academy of Sciences meteorite committee, said early Monday.

A National Labor Relations Board judge has ordered NASA's Jet Propulsion Laboratory to rescind disciplinary actions against five scientists who shared emails at work about a Supreme Court decision on background security checks for JPL employees. Administrative Law Judge William G. Kocol ordered JPL to purge disciplinary letters related to the case from the employee files of Dennis Byrnes, Scott Maxwell, Larry D'Addario, Robert Nelson and William Bruce Banerdt. The five were accused of violating rules against unsolicited spam and bulk email.

Changes in wind direction 15 to 30 miles above Earth's surface can affect mile-deep currents in the North Atlantic by striking an oceanic "Achilles' heel," according to atmospheric scientists. The discovery, published Monday in the journal Nature Geoscience , carries implications for the study of Earth's climate and how we predict its change. Scientists have long understood that events in Earth's stratosphere -- that layer of atmosphere that begins 6 miles above Earth's surface and extends another 25 miles in height  -- influences events in the lower troposphere, where weather occurs.

Astronomers on the hunt for supermassive black holes have discovered one so monstrous that its mass dominates the central hub of its galaxy in a way that defies scientists' expectations about how typical black holes behave. Described in Thursday's edition of the journal Nature, the black hole may push theorists to revamp their ideas of how these mysterious structures grow and evolve. Astrophysicists said they were scratching their heads at how thoroughly this gargantuan black hole - seated in the galaxy NGC 1277, about 220 million light-years away - hogs its galactic bed. Supermassive black holes typically account for just 0.1% of the mass in a galaxy's stellar bulge, the cluster of older stars huddled around the center.

Famed physicist Stephen Hawking set off chatter in the scientific community in late April when he posited the existence of intelligent aliens on his new TV series, "Into the Universe with Stephen Hawking" —adding that it would be best for human beings to avoid contact with them. Hawking speculated that such aliens would likely be nomads, living in ships after sucking their own planet dry of resources, and hopping from one interstellar refueling station to the next. Earth, he said, shouldn't do anything to encourage their visit.

Why are our hands the shape that they are? Compared with those of other apes, the thumb is longer and the palms and fingers are short. Scientist have  a variety of ideas as to why they evolved to be that way: --The comparatively longer thumb allows us so much more dexterity, permitting us to make tools. --The proportions of the hand may be the indirect consequence of natural selection for a foot with a long toe, so handy for keeping balance while walking. (Hand and foot development occur along very similar lines, and many of the same molecules are involved.

A report claiming to find remnants of alien life in meteorites has been broadly dismissed by scientists after its publication Friday in an eccentric online journal. The report was written by Richard Hoover, an engineer at NASA's Marshall Space Flight Center in Huntsville, Ala. He had sliced open a couple of small meteorites, looked at them under a microscope and seen what he thought were the fossils of tiny bacteria called cyanobacteria. Hoover wrote his report, concluding that life is common throughout the universe.