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You might thank your nose for letting you experience the lovely aromas of a good soup, but you probably wouldn't think to thank it for helping you experience other people's emotions!

Hosted by: Hank Green
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The first 1,000 people to click  the link in the description can get a one month free trial of  Skillshare’s Premium Membership. [♪ INTRO] We humans have our noses to thank  for our powerful sense of smell. Most of us, at least, can use our  noses to tell that dinner is ready or that there’s a gas leak.

It can save our lives! But our noses also do a lot of work  they don’t get as much credit for. They pick up chemical cues that  affect us on a subconscious level.

And yet, those cues may play an  important role in our social interactions and our personal well-being -- even  though we have no idea it’s happening. Now, in the past, smell hasn’t gotten  much press compared to our other senses. But a lot of recent research  suggests that our sense of smell is far more important than we first realized.

One big clue is the fact that  we humans are pretty smelly compared to our closest ape relatives. And not for nothing! Our B.

O. reflects a combination of factors, like our genetics, our diet,  and our emotional state. This can all be important information, and  like it or not, our sweat can carry that information to other members of our  species… with no effort on our part. When you smell someone’s BO, your brain  processes the chemical information it contains, and one thing it can  do is influence your emotions.

Among social species like  humans, emotional contagion, or the ability to transmit emotions  from one individual to another through the senses, is common—and pretty useful! For instance, if one individual  sees some danger, like a predator, and starts giving off fear signals,  others may pick up those signals and have a better chance of protecting themselves. Plenty of studies have shown that  humans and other social species transmit emotions through visual cues, like  facial expressions and body language.

And studies had also shown that certain  animals transmit emotions like fear through invisible cues in their  scent, known as chemosignals. So some scientists wondered how much  these chemosignals might play a role in emotional contagion among humans. In a 2012 study, one team of researchers  designed an experiment to find out.

In it, one set of participants watched  videos that would provoke either fear or disgust, while wearing  sweat pads in their armpits. Afterward, a second set of participants  were asked to smell those sweat pads, and the experimenters recorded  their emotional state. Conveniently, the emotions of fear and disgust tend to provoke opposite physical responses.

When you’re scared, your body will typically try to take in more sensory information. So your face will open up  as you breathe more deeply and scan the environment with your eyes. On the other hand, when you’re disgusted, you’ll generally reject sensory information.

Like, you’ll walk past a row of portapotties  and you’ll scrunch up your face, take really shallow breaths, and look around less. Now, these reactions aren’t  always super visible to the eye, but by monitoring their eyes and facial movements, the researchers could tell which facial  muscles were activated in each person, and which emotional state  their expressions reflected. And the authors found that  participants who sniffed disgust sweat tended to display disgust, which  seems like a normal reaction when you’re sniffing sweat pads, but  also, those who sniffed fear sweat would also display fear.

And that’s even though they  had no visual or other cues to suggest those responses. What’s more, they weren’t even consciously aware of the effect the smell was having on them. This suggests that the subconscious  information in another person’s sweat can play an important role in emotional contagion.

And sharing emotions isn’t only useful for protecting against threats in the environment. Literally feeling what other people  feel is the basis of empathy. Various studies have linked empathy  with what’s called prosocial behavior, or behavior that helps other people.

Basically, if we have the  capacity to feel what others feel, we are more likely to look after their well-being. So, in a less direct way, empathy is  also a survival skill for our species. In the past, research has shown how  visual cues can activate our empathy and make us more likely to help people out.

But more recent research has highlighted  the fact that visual cues don’t act alone. For instance, a 2018 study looked  at the role of chemosignals in making us feel empathy. So get this: The researchers used  cotton pads to collect armpit sweat from a group of 16 participants  as they gave fake presentations that were meant to intentionally stress them out.

Then the researchers had a separate  group smell those cotton pads while looking at pictures of  people in different situations. In some pictures, the people were in pain, while in others they were doing something neutral. And as the participants looked at the  pictures, the researchers used an EEG to measure the levels of specific brain  waves that correspond with empathy.

And they found that when the subjects  looked at pictures of people in pain, they had the most empathetic response  while they were smelling sweat that contained stress signals. In fact, even when the subjects looked  at neutral images, they tended to have an empathetic response if they  smelled the sweat with stress signals. They concluded that emotional contagion  through smell has a strong influence on our empathy, and can sometimes  even override what we see.

Scientists still don’t know exactly  what chemicals act as chemosignals, so there’s still plenty of research to be done. But what studies so far have  shown is that these signals that we take in subconsciously are a  really important part of our lives. And… we have BO to thank for the  role it plays in our well-being and the well-being of our society..

Something good for your well-being that  doesn’t stink is picking up new skills and Skillshare can help with that. Skillshare is an online learning community  that offers membership with meaning. With so much to explore, real  projects to create, and the support of fellow-creatives, Skillshare empowers  you to accomplish real growth.

For example, if you’re watching this video  and you’re thinking you’d like to make YouTube videos yourself, you might like the course "YouTube Success: Script,  Shoot & Edit with MKBHD,” taught by Marques Brownlee. Skillshare is always ad-free  so you can focus on learning. Right now, the first 1,000 people  to click the link in the description can get a one month free  trial of Premium Membership.

So thanks! [♪ OUTRO]