Scientists find blood molecule that attracts wolves, repels humans

An endangered gray wolf is pictured in this undated handout photo from the US Fish and Wildlife Service. (File photo: US Fish and Wildlife Service/Handout via Reuters)
Updated 23 October 2017
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Scientists find blood molecule that attracts wolves, repels humans

PARIS: The faintest whiff of a molecule from mammal blood known as E2D sends some animals into a predatory frenzy but frightens others — including people — into retreat, scientists have discovered.
Never before has the same molecule been known to provoke diametrically opposite behaviors in creatures ranging from horse flies to humans, hinting at deep evolutionary roots, they reported in the journal Scientific Reports.
Animals, and especially mammals, use their sense of smell to find food, hook up with partners, and detect danger.
Many of these chemical triggers are specific to one species or work in combination with other odours.
But E2D — said to give blood a metallic aroma — appears to be in a class of its own.
“The odour of blood is characterised by a rare universality,” senior author Johan Lundstrom, a biologist at the Karolinska Institute in Sweden, told AFP.
In earlier research, authors participating in the study isolated E2D from pig’s blood and showed that wild dogs and tigers were no less attracted to its scent than to blood itself.
The new team duplicated those experiments, this time with wolves, and got the same result: the pack licked, bit and protected a piece of wood smeared with a synthetic version of the molecule as if it were a fresh kill.
Blood-sucking horse flies were likewise drawn to it, showing equal enthusiasm for E2D and animal blood.
But what about the hunted rather than the hunter?
If the molecule has persisted across tens or even hundreds of millions of years, the scientists reasoned, then perhaps they would react too, though not in the same way.
“We hypothesised that prey species would be under evolutionary pressure to become sensitive to E2D, to help them avoid an area where a bloodbath is going on,” said Lundstrom.
Sure enough, rodents in a cage recoiled from the molecule, as much as they did from the red stuff.
When it came to humans, the researchers were not sure what to expect. Would people show blood lust or fear?
And how to find out?
“We couldn’t just expose people to the odour and ask, ‘how do you feel?’,” said Lundstrom. “We had to find objective measures not based on subjective feelings.”
They did this in three ways.
In one standardised test, subconsciously leaning forward while standing indicates attraction, while a slight tilt backwards means one senses danger.
Forty volunteers smelled three scents, none more or less “pleasant” than the other. They did not know when the molecules were released, and knew nothing about the study or its relationship to blood.
Not only did E2D cause people to rock back on their heels, it only took a tiny dose.
“Humans are able to detect E2D at concentrations of less than one part per trillion,” said co-author Matthias Laska, a zoologist at Linkoping University in Sweden.
“This is uncommon. For the majority of odorants which have been tested with humans, the detection threshold is in the parts-per-million or billion range,” he told AFP.
The researchers also measured “micro-sweating,” and gauged response time in a visual test in which quick, accurate answers indicate a perceived threat.
In all three experiments, subjects exposed to E2D showed signs of stress and fear.
That humans react more like mice than wolves is not that surprising, the authors say.
“Although humans are thought to be opportunistic predators, palaeontological data indicate that early primates” — our distant relatives — “were small-bodied insect eaters,” said the study, published Friday.
The hunting of large prey such as mammoths and sabre-tooth tigers are relatively recent chapters in the human saga, they note.
E2D molecules occur as a by-product when lipids, or fats, in blood break down upon exposure to oxygen in the air.


Massive diamond cache detected beneath Earth’s surface

Updated 18 July 2018
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Massive diamond cache detected beneath Earth’s surface

  • “This shows that diamond is not perhaps this exotic mineral..."
  • These naturally occurring precious minerals are located far deeper than any drilling expedition has ever reached

WASHINGTON: There’s a load of bling buried in the Earth.
More than a quadrillion tons of diamonds to be exact — or one thousand times more than one trillion — US researchers at the Massachusetts Institute of Technology reported this week.
But don’t expect a diamond rush. These naturally occurring precious minerals are located far deeper than any drilling expedition has ever reached, about 90 to 150 miles (145 to 240 kilometers) below the surface of our planet.
“We can’t get at them, but still, there is much more diamond there than we have ever thought before,” said Ulrich Faul, a research scientist in MIT’s Department of Earth, Atmospheric, and Planetary Sciences.
“This shows that diamond is not perhaps this exotic mineral, but on the scale of things, it’s relatively common.”
Using seismic technology to analyze how sound waves pass through the Earth, scientists detected the treasure trove in rocks called cratonic roots, which are shaped like inverted mountains that stretch through the Earth’s crust and into the mantle.
These are “the oldest and most immovable sections of rock that lie beneath the center of most continental tectonic plates,” explained MIT in a statement.
The project to uncover deep Earth diamonds began because scientists were puzzled by observations that sound waves would speed up significantly when passing through the roots of ancient cratons.
So they assembled virtual rocks, made from various combinations of minerals, to calculate how fast sound waves would travel through them.
“Diamond in many ways is special,” Faul said.
“One of its special properties is, the sound velocity in diamond is more than twice as fast as in the dominant mineral in upper mantle rocks, olivine.”
They found that the only type of rock that matched the speeds they were detecting in craton would contain one to two percent diamond.
Scientists now believe the Earth’s ancient underground rocks contain at least 1,000 times more diamond than previously expected.
Still, very few of these gems are expected to make their way to the jewelry store.
Diamonds are made from carbon, and are formed under high-pressure and extreme temperatures deep in the Earth.
They emerge near the surface only through volcanic eruptions that occur rarely — on the order of every few tens of millions of years.