Chemical fingerprints: Sensing emotions in a theater and life across interstellar space

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It’s one of the first sensing phenomena to appear in evolution. Dogs use it to sniff out food, potential mates, or trace amounts of explosives; we use it to to enjoy meals; astronomers are trying to apply it to determine whether distant planets harbor life; and soon industry will be using it as a window into the your emotions.

We’re talking about chemical fingerprints—combinations of different chemical compounds in the environment that can be sensed as taste or smell, or picked out by special instruments. The newest application is the utilization of changes in levels of carbon dioxide (CO2) and other gases to determine whether a test audience watching a movie, or television, is amused, angry or scared.

Research from the Max Planck Institute in Germany published recently in Scientific Reports has demonstrated that people watching movies release CO2 and a common organic compound called isoprene in specific ratios that correlate with whether they are excited, at the edges of their seats, or experiencing other emotions that change rapidly during a film.

“You hear the music and see the pictures, but you don’t realize there are chemical signals in the air,” said Jonathan Williams in an interview, an atmospheric chemist who worked on the study. “There’s an invisible concerto going on.”


By no means is one study enough to define a reliable means to sense emotions using only exhaled chemical signatures, but  “It’s something to investigate,” Williams explained. “We have scratched the surface and it’s made a funny smell.”

As atmospheric scientists, Williams and his colleagues did not begin the movie study out of a desire to help the film industry obtain emotional data more efficiently than by gauging laughter, oohs and ahhs, a the other usual metrics. What led to the new study was instead something more global: increased levels of greenhouse gases had been noticed entering the atmosphere from a soccer stadium—too much to be explained simply by the presence of a large number of people.

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Rather than looking at the Earth, other scientists are working on means to monitor chemical fingerprints of life in the atmospheres of distance planets. Right now, for instance, the European and Russian Space Agencies are preparing for a probe called the Exo Mars Trace Gas Orbiter (TGO) to get more accurate measurements methane in the Martian atmosphere than have been obtain previous by other instruments. The TGO probe will also measure water vapour, nitrogen oxides, and acetylene.

Based on the combined results of measurements for all of those gases, it will be possible for astrobiologists to make an assessment of whether microorganisms must be affecting the atmosphere of the Red Planet, but Mars is relatively close. In the years to come, NASA will also be using the James Webb Space Telescope and other instruments on the horizon to look at atmospheres of planets orbiting other stars many light years away to determine whether they harbor life. Scientists will be able to assess levels of oxygen, indicative of photosynthesis, and methane and other chemicals resulting from a plethora of other life processes—leading to oohs and ahhhs from the human population outdoing those from any new movie.


David Warmflash is an astrobiologist, physician and science writer. Follow @CosmicEvolution to read what he is saying on Twitter.

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