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Scientists Identify the Chemical That Makes Death Smell Scary

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The smell of death isn’t just gross—it might be downright scary. Scientists have identified a chemical associated with death and decay that appears to function as a warning signal, activating the body’s threat management response and making people more vigilant. 

A University of Kent psychologist and an Arkansas Tech University behavioral scientist argue that putrescine—a chemical compound unleashed by the fatty acids that break down when dead tissue decays—is an olfactory threat signal for humans. In four different tests published in a study in the journal Frontiers in Psychology, putrescine exposure put people on edge, eliciting cognitive reactions related to escaping threats. 

In one trial, 60 people were asked to open a jar and give its contents a sniff, inhaling either the pungent smell of putrescine or the similarly gross smell of ammonia. Afterward, those who smelled the death smell were quicker to react to a red dot randomly presented on a screen in the lab, indicating that the smell made people more vigilant. 

In two more tests, a total of more than 100 people were stopped on a university campus and asked if they had time to participate in a smell test. After sniffing putrescine, people walked away faster than those who had smelled ammonia or water (as timed by a hidden experimenter with a stopwatch).

In a fourth experiment, 65 people filled out questionnaires that were subtly scented with putrescine, water, and ammonia, such that none of the participants were aware of the scent. They read an essay designed to elicit a response against an "out-group member," someone who didn’t share their values. In this case, it was supposedly written by a Middle Eastern exchange student in the UK who criticized Western values and predicted their decline. Afterward, people filled out a questionnaire about how likable the essay’s author was and whether his ideas should be publicized. Those who smelled putrescine were significantly more hostile towards the foreign student than those who filled out ammonia-soaked questionnaries, suggesting that subconsciously, the scent of putrescine elicited a defensive response. 

The chemical compound “could serve as a warning signal that mobilizes protective responses to deal with threats,” the authors write, evoking people’s fight-or-flight response. This is one of the first studies to point to a chemical threat signal of this type that isn’t transmitted through sweat. 

[h/t: Brain Decoder]

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Hulton Archive/Getty Images
6 Radiant Facts About Irène Joliot-Curie
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Hulton Archive/Getty Images

Though her accomplishments are often overshadowed by those of her parents, the elder daughter of Marie and Pierre Curie was a brilliant researcher in her own right.


A black and white photo of Irene and Marie Curie in the laboratory in 1925.
Irène and Marie in the laboratory, 1925.
Wellcome Images, Wikimedia Commons // CC BY 4.0

Irène’s birth in Paris in 1897 launched what would become a world-changing scientific dynasty. A restless Marie rejoined her loving husband in the laboratory shortly after the baby’s arrival. Over the next 10 years, the Curies discovered radium and polonium, founded the science of radioactivity, welcomed a second daughter, Eve, and won a Nobel Prize in Physics. The Curies expected their daughters to excel in their education and their work. And excel they did; by 1925, Irène had a doctorate in chemistry and was working in her mother’s laboratory.


Like her mother, Irène fell in love in the lab—both with her work and with another scientist. Frédéric Joliot joined the Curie team as an assistant. He and Irène quickly bonded over shared interests in sports, the arts, and human rights. The two began collaborating on research and soon married, equitably combining their names and signing their work Irène and Frédéric Joliot-Curie.


Black and white photo of Irène and Fréderic Joliot-Curie working side by side in their laboratory.
Bibliothèque Nationale de France, Wikimedia Commons // Public Domain

Their passion for exploration drove them ever onward into exciting new territory. A decade of experimentation yielded advances in several disciplines. They learned how the thyroid gland absorbs radioiodine and how the body metabolizes radioactive phosphates. They found ways to coax radioactive isotopes from ordinarily non-radioactive materials—a discovery that would eventually enable both nuclear power and atomic weaponry, and one that earned them the Nobel Prize in Chemistry in 1935.


The humanist principles that initially drew Irène and Frédéric together only deepened as they grew older. Both were proud members of the Socialist Party and the Comité de Vigilance des Intellectuels Antifascistes (Vigilance Committee of Anti-Fascist Intellectuals). They took great pains to keep atomic research out of Nazi hands, sealing and hiding their research as Germany occupied their country, Irène also served as undersecretary of state for scientific research of the Popular Front government.


Irène eventually scaled back her time in the lab to raise her children Hélène and Pierre. But she never slowed down, nor did she stop fighting for equality and freedom for all. Especially active in women’s rights groups, she became a member of the Comité National de l'Union des Femmes Françaises and the World Peace Council.


Irène’s extraordinary life was a mirror of her mother’s. Tragically, her death was, too. Years of watching radiation poisoning and cancer taking their toll on Marie never dissuaded Irène from her work. In 1956, dying of leukemia, she entered the Curie Hospital, where she followed her mother’s luminous footsteps into the great beyond.

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Researchers Pinpoint the Genes Behind the Durian's Foul Stench
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Durian is a popular fruit in parts of southeast Asia. It's also known for having the most putrid, off-putting odor of any item sold in the produce section. Even fans of durian know why the fruit gets a bad rap, but what exactly causes its divisive scent is less obvious. Determined to find the answer, a team of researchers funded by "a group of anonymous durian lovers" mapped the fruit's genome, as reported by the BBC.

The study, published in the journal Nature Genetics [PDF], contains data from the first-ever complete genetic mapping of a durian fruit. It confirms that durian's excess stinkiness comes from sulfur, a chemical element whose scent is often compared to that of rotten eggs.

Analysis of the fruit's chemical makeup has been done in the past, so the idea that sulfur is a major contributor to its signature smell is nothing new. What is new is the identification of the specific class of sulfur-producing genes. These genes pump out sulfur at a "turbocharged" rate, which explains why the stench is powerful enough to have durian banned in some public areas. It may seem like the smell is a defense mechanism to ward off predators, but the study authors write that it's meant to have the opposite effect. According to the paper, "it is possible that linking odor and ripening may provide an evolutionary advantage for durian in facilitating fruit dispersal." In other words, the scent attracts hungry primates that help spread the seeds of ripe durian fruits by consuming them.

The revelation opens the door to genetically modified durian that are tweaked to produce less sulfur and therefore have a milder taste and smell. But such a product would likely inspire outrage from the food's passionate fans. While the flavor profile has been compared to rotten garbage and dead animal meat, it's also been praised for its "overtones of hazelnut, apricot, caramelized banana, and egg custard" by those who appreciate its unique character.

[h/t BBC]


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