How Can Vultures Eat Rotten Roadkill And Survive?

iSebastian Kennerknecht/Minden/Corbis

A turkey vulture makes quick work of a dead rabbit at Martin Luther King Jr. Regional Shoreline park in Oakland, Calif.

You might wonder why 48 million Americans get food poisoning every year, yet there are some animals that seem to be immune from even the nastiest germs.

We're talking here about vultures, which feast on rotting flesh that is chockablock full of bacteria that would be deadly to human beings. In fact, vultures have a strong preference for that kind of food.

"The real question is how can they actually stand eating things like this," says Lars H. Hansen, a professor of molecular microbial ecology at Aarhus University in Denmark.

Hansen started chewing over this question in a conversation with colleagues who study bacteria that form ecosystems within animal intestines. Maybe, they thought, vultures have some helpful bacteria in their guts to help them tolerate these otherwise deadly germs.

They turned to a Michael Roggenbuck at the University of Copenhagen, because he studies communities of intestinal bacteria.

"When Lars told me about this study I was very, very interested in that one," Roggenbuck tells NPR. "I thought, wow, a vulture! That would be very exciting."

Roggenbuck was working on his Ph.D. at the time. He set to work examining the guts of 50 turkey vultures and black vultures that had been trapped and killed near Nashville.

He expected to see a huge variety of bacteria in the gut, as you find inside human intestines. Instead, he found an ecosystem dominated by two species of bacteria, both well-known poisons: Fusobacteria, which can cause blood infections; and Clostridium, which produces deadlybotulism toxins.

So why didn't the vultures get sick from a gutful of nasty germs? "There are several possibilities," Roggenbuck says.

They could have developed immunity to these toxins as they evolved to eat their everyday diet. Also, other disease-causing germs are likely killed in the stomach, before they even get into the intestine, Hansen suggests. He says vulture stomach acid is 10 to 100 times stronger than human stomach acid, "so it seems like the stomach itself is a very harsh environment."

"Another hypothesis could be that they're actually using the bacteria in the stomach as some sort of probiotics," Hansen says. By having a gutful of a few tolerable species of bacteria, it's possible that those would crowd out other deadly microbes.

Hansen, Roggenbuck and their colleagues published their results Tuesday in the journal Nature Communications.

Hansen is looking for larger lessons from this trip into the secret lives of vultures.

"I think it's mind-boggling that organisms that are perceived as very bad for you, seem to be very useful for other biological creatures, such as the vultures," he says. "So I think that's amazing."

Wildlife biologists say vultures aren't alone in being resistant to botulism toxins. Tonie Rocke at the USDA's National Wildlife Health Center in Madison, Wisc., says lots of birds seem to handle botulism spores just fine. But vultures have to cope with massive amounts of deadly germs.

"They're very hardy beasts, I would say so," Rocke says. "But given that, they've also suffered their share of mortality."

Vultures can be poisoned, for example, by lead, or by ibuprofen-like drugs given to cattle in Asia. Curiously those drugs, while deadly to vultures, are safe for human consumption.

What Does the Liver Do?

GPS Satellites Might Be Able to Detect Dark Matter

Image from Science Illustrated

Dark matter has historically been one of the most elusive substances in the universe, but, according to new research, the key to finding it might be right under our noses. A new study from an international research team shows that we may be able to detect dark matter using GPS satellites, as a result of their usage of atomic clocks.

Dark matter is a hypothetical type of matter that doesn't interact with any kind of electromagnetic radiation, and therefore is virtually impossible to observe. Physicists have long theorized its existence in order to account for gravitational effects on normal matter and for the overall structure of the universe. The search for dark matter is one of the most prominent objectives in modern particle physics, as it is thought to make up 85% of the matter in the known universe. Most in the scientific community essentially take for granted that dark matter exists, but continue to search for proof of its existence and answers as to what type of particle composes it.

Co-author Andrei Derevianko, of the University of Nevada, states the dark matter problem as follows: "We know the dark matter must be there, for example, because it is seen to bend light around galaxies, but we have no evidence as to what it might be made of. If the dark matter were not there, the normal matter that we know about would not be sufficient to bend the light as much as it does. That's just one of the ways scientists know there is a massive amount of dark matter somewhere out there in the galaxy."

The new study proposes that dark matter consists not of particle-like matter, which is the current prevailing theory, but of macroscopic imperfections, or "cracks," in the fabric of spacetime. If this conception of dark matter is correct, then we should theoretically be able to detect it using an atomic clock system. Atomic clocks, like the ones used in GPS satellites, operate according to atomic physics, rather than nuclear physics as normal clocks do. In other words, while the pendulum in a normal clock oscillates according to all the macroscopic, conventional rules of physics, atomic clocks literally oscillate according to the frequency of an atom. Atomic clocks are so accurate precisely because they work on such a fundamental level, which makes them ideal candidates to measure anomalies in spacetime, as little else could interfere with the clock's accuracy.

From the paper: "A transient-in-time change of fundamental constants can be induced by dark-matter objects... During the encounter with an extended dark-matter object, as it sweeps through the network, initially synchronized clocks will become desynchronized."

A diagram explaining the desynchronization of two atomic clocks:

[Credit: Andrei Derevianko]

"We envision using the GPS constellation as the largest human-built dark-matter detector," said Derevianko. 

Collaborator Geoff Blewitt, director of the Nevada Geodetic Laboratory, explained the mechanism of the dark matter's interference as follows: "As the dark matter blows by, it would occasionally cause clocks of the GPS system to go out of sync with a tell-tale pattern over a period of about 3 minutes. If the dark matter causes the clocks to go out of sync by more than a billionth of a second we should easily be able to detect such events." 

The researchers have only just begun to test and analyze the actual data from the satellites, but their theories have been extremely well-received in the scientific community. The above paper was published in the well-regarded and peer-reviewed journal, Nature Physics, and their presentations of the hypothesis at conferences earlier this year were met with an onslaught of support.

A ‘Stupidity’ Virus Has Been Discovered

A virus known to attack green algae in lakes and rivers can also infect human brains -- and it’s making dummies out of us. The virus, called ATCV-1, can impair cognitive activity, learning and memory, essentially making a person who has the virus less intelligent, researchers in the U.S. have found. Scientists said this is the first time the virus has been observed in people.  

“This is a striking example showing that the ‘innocuous’ microorganisms we carry can affect behavior and cognition,” Robert Yolken, a virologist at Johns Hopkins Medical School in Maryland, who led the original study, told the Independent. All people have physiological differences “encoded in the set of genes each inherits from parents, yet some of these differences are fueled by the various microorganisms we harbor and the way they interact with our genes,” Yolken said.

Scientists discovered the virus accidentally while working on an unrelated study into microbes in the human throat. Throat swabs drawn from study volunteers showed unexpected traces of ATCV-1 in their DNA. Out of the 92 healthy adults screened in the study, nearly 44 percent of them had the virus, the authors said.

Study participants who had the virus performed around 10 percent worse on cognitive tests. Additionally, researchers noted the presence of the virus was correlated with lower attention spans and a “statistically significant decrease in … visual processing and visual motor speed.” While the virus is found in freshwater, there was no indication the only people who had it were swimmers and boaters. “These are agents that we carry around for a long time and that may have subtle effects on our cognition and behavior,” Yolken toldHealthline. "We're really just starting to find out what some of these agents that we're carrying around might actually do.”

Subsequent tests involving mice produced similar results, Newsweek reported. Researchers inserted infected green algae into the mouths of mice and had them perform a series of lab tests. It took animals that had been injected with the virus 10 percent longer to find their way out of mazes. They also spent 20 percent less time exploring new objects than uninfected mice, researchers found.