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

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.


South Korean TV ‘reunites’ mother with dead daughter in virtual reality show

This undated handout photo provided on February 14, 2020 by South Korea's Munhwa Broadcasting Corporation (MBC) in Seoul shows a scene of a documentary "I met you" where a mother meets her dead daughter through virtual reality. (AFP)
Updated 18 February 2020

South Korean TV ‘reunites’ mother with dead daughter in virtual reality show

  • The footage began with the girl — who died of leukaemia in 2016 — emerging from behind a pile of wood in a park, as if playing hide-and-seek
  • “I have missed you Na-yeon,” she told the computer-generated six-year-old, her hands moving to stroke her hair

SEOUL: A tearful reunion between a mother and her dead daughter via advanced virtual reality for a South Korean television has become an online hit, triggering fierce debate about voyeurism and exploitation.
The footage began with the girl — who died of leukaemia in 2016 — emerging from behind a pile of wood in a park, as if playing hide-and-seek.
“Mum, where have you been?” she asks. “I’ve missed you a lot. Have you missed me?“
Tears streaming down her face, Jang Ji-sung reached out toward her, wracked with emotion.
“I have missed you Na-yeon,” she told the computer-generated six-year-old, her hands moving to stroke her hair.
But in the real world, Jang was standing in front of a studio green screen, wearing a virtual reality headset and touch-sensitive gloves, her daughter’s ashes in a locket around her neck.
At times the camera cut to Jang’s watching husband and their three surviving children, wiping away tears of their own.
A nine-minute clip of the Munhwa Broadcasting Corporation (MBC) documentary “I met you” has been watched more than 13 million times in a week on Youtube.
Many viewers offered Jang their sympathy and support for the concept.
“My mother unexpectedly passed away two years ago and I wish I could meet her through virtual reality,” said one.
But media columnist Park Sang-hyun said the documentary amounted to exploitation of personal pain.
“It’s understandable a grief-stricken mother would wish to meet her late daughter. I would do the same,” he told AFP.
“The problem lies in that the broadcaster has taken advantage of a vulnerable mother who lost a child for sake of the viewer ratings.”
“If the mother had been counselled before the filming,” he added, “I wonder what kind of a psychiatrist would approve this.”

It took eight months of filming and programming to create the virtual Na-yeon, but the makers of the documentary insisted the broadcast was intended to “console the family” rather than promote virtual reality in ultra-wired South Korea.
The technology presented a “new way to keep loved ones in memory,” one of the producers told reporters.
Jang herself — who has her daughter’s name and date of birth tattooed on her arm in memory — hoped the program could “console” others who had lost loved ones.
“Even though it was a very brief... I was really happy in the moment,” she wrote on her blog — which she has since turned private.
During the broadcast the two sat at a table to celebrate Na-yeon’s missing birthdays, singing “happy birthday” together.
Before blowing out the candles, Na-yeon made a birthday wish: “I want my mother to stop crying.”