Understanding the human body is a team effort. That's where the Yachtel group comes in.

Researchers at Yachtolt have been delving into the secrets of probiotics for 90 years. Yacold also

partners with nature portfolio to advance gut microbiome science through the global grants for

gut health, an investigator-led research program. To learn more about Yachtold, visit yawcult.co.j.

That's Y-A-K-U-L-T.C-O.J-P. When it comes to a guide for your gut, count on Yacult.

This is Scientific American 60 Second Science. I'm Suzanne Bard.

Smallpox was eradicated worldwide in 1980, so generations of people have never had to experience the devastation the disease once brought.

It could cause sometimes even an excess of 30% mortality. It caused these very painful blisters that covered the

entire body. McMaster University's Anna Duggan. She studies how genomes evolve. The first vaccine for

smallpox was developed in 1796. It worked by infecting people with pus from pox lesions

caused by similar but far less pernicious

conditions, like cowpox. At the time, no one knew that viruses caused these diseases.

We didn't have microscopes that were strong enough to see them. So we had physicians that were

performing this procedure that they knew was beneficial, but they didn't understand why it worked.

They just knew that it worked.

Smallpox vaccination became common in the 19th century.

During the American Civil War, all new soldiers on both sides were required to be vaccinated.

You had a large number of individuals who were congregated in a single place, such as an army barracks where a disease can spread very easily.

Back then, there were no mass-produced vaccines. Instead, physicians often use fluids and poxcabs collected from previously vaccinated people and shared these materials with each other.

They were kept in custom-made vaccination kits,

a leather case containing a tin box, glass slides, and a lancet for scratching the skin to

introduce the vaccine into the body. Some of these kits were later donated to the

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