Reverse-Engineering the Quantum Compass of Birds

Reverse-Engineering the Quantum Compass of Birds | Wired Science | Wired.com

Scientists are coming ever closer to understanding the cellular navigation tools that guide birds in their unerring, globe-spanning migrations.

The latest piece of the puzzle is superoxide, an oxygen molecule that may combine with light-sensitive proteins to form an in-eye compass, allowing birds to see Earth's magnetic field.

"It connects from the subatomic world to a whole bird flying," said Michael Edidin, an editor of Biphysical Journal, which published the study last week. "That's exciting!"

The superoxide theory is proposed by Biophysicist Klaus Schulten of the University of Illinois at Urbana-Champaign, lead author of the study and a pioneer in avian magnetoreception. Schulten first hypothesized in 1978 that some sort of biochemical reaction took place in birds' eyes, most likely producing electrons whose spin was affected by subtle magnetic gradients.

In 2000, Schulten refined this model, suggesting that the compass contained a photoreceptor protein called cryptochrome, which reacted with an as-yet-unidentified molecule to produce pairs of electrons that existed in a state of quantum entanglement — spatially separated, but each still able to affect the other.

According to this model, when a photon hits the compass, entangled electrons are scattered to different parts of the molecule. Variations in Earth's magnetic field cause them to spin in different ways, each of which leaves the compass in a slightly different chemical state. The state alters the flow of cellular signals through a bird's visual pathways, ultimately resulting in a perception of magnetism.

Far-fetched as it sounds, subsequent research from multiple groups has found cellular evidence of such a system. Molecular experiments suggest that it's indeed sensitive to Earth's geomagnetics, and computational models suggest a level of quantum entanglement only dreamed of by physicists, who hope to use entangled electrons to store information in quantum computers.

But though cryptochrome is likely part of the compass, the other part is still unknown. In April, another group of magnetoreception researchers showed that oxygen could interact with cryptochrome to produce the necessary electron entanglements. Schulten's latest proposed role for superoxide, an oxygen anion found in bird eyes, fits with their findings.

Edidin cautioned that "this is still not an experimental demonstration. It's a possibility."

As for the perceptual result of the compass, it remains a mystery. Some researchers think birds might see a dot at the edge of their vision, swiveling according to the direction they're facing. Others think it might produce effects of color or hue. Perhaps migrating birds fly towards the light.

Extreme Life

Extreme Life Thrives Where the Livin' Ain't Easy | Wired Science | Wired.com

Once upon a time, scientists routinely found life in places where it wasn't supposed to exist. That doesn't happen anymore, and not because the pace of discovery has slowed. If anything, it's accelerated. It's simply become clear that life can exist almost anywhere on Earth.

After 3 billion years of evolution, life has flowed into every last nook and cranny, from the bottom of the sea to the upper edge of the stratosphere. From blazing heat and freezing cold to pure acidity and atomic bomb-caliber radiation, there's seemingly no stress so great that some bug can't handle it.

Desulforudis audaxviator is perhaps the one truly singular microbe. Every other known organism exists in a system in which at least some nutrients are provided by other creatures. But not D. audaxviator, which was discovered in a South African mine shaft, two miles beneath Earth's surface and entirely alone. Using radioactivity from uranium-containing rocks as energy, it can harvest or metabolize every nutrient it needs from surrounding rock and gas — the world's only known single-species ecosystem.

Extreme Life

Extreme Life Thrives Where the Livin' Ain't Easy | Wired Science | Wired.com

Ferroplasma acidophilum can grow in a pH of zero — conditions that make sulfuric acid look like mineral water. Found in the toxic outflow of a California gold mine, it uses iron as the central structural element of nearly all its proteins.

Image: Helmholtz Centre for Infection Research (left), NASA (right)

Requests to the Right Ear Are More Successful

Requests to the Right Ear Are More Successful Than to the Left | Wired Science | Wired.com

You're in a loud and sweaty Italian dance club when a woman approaches you. To be heard over the techno, she leans in close and yells into your ear, "Hai una sigaretta?"

If she spoke into your right ear, you would be twice as likely to give her a cigarette than if she asked by your left ear, according to a new study that employed this methodology in the clubs of Pescara, Italy. Of 88 clubbers who were approached on the right, 34 let the researcher bum a smoke, compared with 17 of 88 whom she approached on the left.

"The present work is one of the few studies demonstrating the natural expression of hemispheric asymmetries, showing their effect in everyday human behavior," write psychologists Daniele Marzoli and Luca Tommasi of the University G. d'Annunzio in Italy.

It's the latest in a series of studies that show that sound from both human ears is processed differently within the brain. Researchers have noted that humans tend to have a preference for listening to verbal input with their right ears and that given stimulus in both ears, they'll privilege the syllables that went into the right ear. Brain scientists hypothesize that the right ear auditory stream receives precedence in the left hemisphere of the brain, where the bulk of linguistic processing is carried out.

What's surprising about the study is that ear choice had such a decided impact on the behavior of participants in a natural, or as the researchers put it, ecological, setting. Why would people feel more generous when their right ears are addressed?

Marzoli and Tommasi write that some work has shown that the left and right hemispheres of the brain appear to be tuned for positive and negative emotions, respectively. Talk into the right ear and you send your words into a slightly more amenable part of the brain.

"These results seem to be consistent with the hypothesized differential specialization of right and left hemispheres," they write.

In addition to the direct cigarette-ask study, they also simply observed people interacting and also asked for cigarettes without directing their requests towards a particular ear. The Italian researchers picked the night club setting because the loud music allowed the cigarette-asker to approach people and speak directly into one ear without seeming "odd."

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