Sign up for our daily briefing

Make your busy days simpler with Axios AM/PM. Catch up on what's new and why it matters in just 5 minutes.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Catch up on coronavirus stories and special reports, curated by Mike Allen everyday

Catch up on coronavirus stories and special reports, curated by Mike Allen everyday

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Denver news in your inbox

Catch up on the most important stories affecting your hometown with Axios Denver

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Des Moines news in your inbox

Catch up on the most important stories affecting your hometown with Axios Des Moines

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Minneapolis-St. Paul news in your inbox

Catch up on the most important stories affecting your hometown with Axios Twin Cities

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Tampa Bay news in your inbox

Catch up on the most important stories affecting your hometown with Axios Tampa Bay

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Charlotte news in your inbox

Catch up on the most important stories affecting your hometown with Axios Charlotte

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Sam Jayne / Axios

This week, scientists reported they'd figured out the features of smiles that convey different emotions. The muscles that produce these expressions were first studied in a series of startling experiments by French neurologist Guillaume-Benjamin-Amand Duchenne.

The experiment: In the mid-1800s, Duchenne used small probes to electrically stimulate muscles in the faces of six different people and reproduce various expressions. He built his own electroshock apparatus and enlisted a photographer to use the then newly developed camera to capture the fleeting expressions.

What he found: Duchenne described the muscle actions that produce more than 30 distinct emotions, ranging from doubt and stupefaction to joy and terror (with and without pain or torture). He found that a combination of the muscle that pulls the lips up at the corners and the involuntary action of the orbicularis oculi muscle around the eye created genuine smiles of happiness. When a smile is faked, it doesn't engage the eye muscle, he proposed. (Duchenne saw the face as the reflection of the soul so his observation about voluntary v. involuntary action is an important if loaded one.)

The legacy: Charles Darwin wrote about the importance and care of Duchenne's work in the introduction to his book, The Expression of the Emotions in Man and Animals. Genuine smiles were dubbed Duchenne ones and several diseases of muscle tissue —for example, Duchenne muscular dystrophy — bear his name. His claim that the involuntary action of the eye muscle in true smiles can't be faked has persisted, though recent studies suggest people can deliberately produce a Duchenne smile.

Source: Wellcome Trust
The facial expression of moderate cruelty on the human face being induced by electrical currents.Source: Wellcome Trust

Go deeper

Focus group: Former Trump voters say he should never hold office again

Illustration: Sarah Grillo/Axios

"Relief" is the top emotion some swing voters who used to support Donald Trump say they felt as they watched President Biden's swearing-in, followed by "hope."

Why it matters: For voters on the bubble between parties, this moment is less about excitement for Biden or liberal politics than exhaustion and disgust with Trump and a craving for national healing. Most said Trump should be prohibited from ever holding office again.

Updated 14 hours ago - Politics & Policy

Coronavirus dashboard

Illustration: Eniola Odetunde/Axios

  1. Health: Most vulnerable Americans aren't getting enough vaccine information — Fauci says Trump administration's lack of facts on COVID "very likely" cost lives.
  2. Politics: Biden unveils "wartime" COVID strategyBiden's COVID-19 bubble.
  3. Vaccine: Florida requiring proof of residency to get vaccine — CDC extends interval between vaccine doses for exceptional cases.
  4. World: Hong Kong to put tens of thousands on lockdown as cases surge.
  5. Sports: 2021 Tokyo Olympics hang in the balance.
  6. 🎧 Podcast: Carbon Health's CEO on unsticking the vaccine bottleneck.

Trump impeachment trial to start week of Feb. 8, Schumer says

Senate Majority Leader Chuck Schumer. Photo: The Washington Post via Getty

The Senate will begin former President Trump's impeachment trial the week of Feb. 8, Majority Leader Chuck Schumer announced Friday on the Senate floor.

The state of play: Schumer announced the schedule after reaching an agreement with Republicans. The House will transmit the article of impeachment against the former president late Monday.