Archivo: Science

Poor oral health is a risk factor for Alzheimer’s disease. What’s not clear is whether gum disease causes the disorder or is merely a result—many patients with dementia can’t take care of their teeth, for example. Now, a privately sponsored study has confirmed that the bacteria that cause gum disease are present in the brains of people with Alzheimer’s, not just in their mouths. The study also finds that in mice, the bacteria trigger brain changes typical of the disease.

A new study of the genes of more than 6000 people from five Latin American countries undercuts the simplistic racial assumptions often made from skin color.

The compound eyes of the common fruit fly are normally brick red. But in neurologist Tom Lloyd’s lab at Johns Hopkins University School of Medicine in Baltimore, Maryland, many of the fly eyes are pocked with white and black specks, a sign that neurons in each of their 800-odd eye units are shriveling away and dying.

A new Canadian radio telescope, not yet fully operational, has already detected more than a dozen of the mysteriously brief blasts from deep space known as fast radio bursts (FRBs). One is only the second known to flash repeatedly, researchers reported here today at the annual meeting of the American Astronomical Society. The early results from the Canadian Hydrogen Intensity Mapping Experiment (CHIME) suggest the scope is well on its way to adding hundreds or even thousands of FRBs to the 60 or so already known—hopefully revealing the source of these powerful millisecondslong pulses in the process.

The pinnacle of beauty to most people is a symmetrical face, one without any major left-right differences. But for blind Mexican cavefish (Astyanax mexicanus), asymmetry may be a lifesaver. That’s because their lopsided skulls may help them feel their way along dark cave walls—similar to a person navigating by touch in the dark. That behavior, presented here this week at the annual meeting of the Society for Integrative and Comparative Biology, suggests being a little “off” can have evolutionary benefits.

Leafcutter ants are known for producing lots of trash. In fact, the species Atta colombica (above) can create bathtub-size, thigh-high mounds of refuse that contain not only leaves, but also ant poop, bacteria, and dead ants. Now, researchers have discovered these massive compost piles are potent sources of greenhouse gases.

Paleobotanists exploring a site near the Dead Sea have unearthed a startling connection between today’s conifer forests in the Southern Hemisphere and an unimaginably distant time torn apart by a global cataclysm. Exquisitely preserved plant fossils show the podocarps, a group of ancient evergreens that includes the massive yellowwood of South Africa and the red pine of New Zealand, thrived in the Permian period, more than 250 million years ago. That’s tens of millions of years earlier than thought, and it shows that early podocarps survived the “great dying” at the end of the Permian, the worst mass extinction the planet has ever known.

Some 125,000 years ago, during the last brief warm period between ice ages, Earth was awash. Temperatures during this time, called the Eemian, were barely higher than in today’s greenhouse-warmed world. Yet proxy records show sea levels were 6 to 9 meters higher than they are today, drowning huge swaths of what is now dry land.

Mars’s methane has gone missing. Scientists first detected traces of the gas—a critical indicator of life on Earth—in the planet’s atmosphere decades ago. But today, researchers reported that a European satellite hasn’t spotted a single trace of methane. The finding, if it holds up, could complicate scientific dreams that martian microbes might be spewing the gas in the planet’s subsurface.

Australia’s splendid assassin fly (Blepharotes splendidissimus) earns its fearsome moniker. About the size of a bottle cap and sporting a similar metallic luster, they ambush butterflies and dragonflies in midair, killing them with a venomous bite. Now, scientists have discovered that even the larvae of these flies are vicious.