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 Yachtolt, visit yawcult.co.

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

This is Scientific American's 60-second science. I'm Christopher in Taliatta.

The square footage of a home tends to be a measure of wealth. Compare the sizes of dwellings in a city,

and you'll begin to get a picture of rich and poor, and how wealth is distributed.

Now researchers have used that modern metric on ancient settlements. They investigated housing-based wealth at 63

archaeological sites, from old-world places like Mesopotamia to New World sites like

Mesa Verde and Colorado. As expected, the wealth differential widened as agriculture took off,

and it kept growing in the old world. But in the Americas, the gap suddenly stopped growing,

about 2,500 years after the first crops showed up. Well, this was a surprise, first of all.

Timothy Kohler is an archaeologist at Washington State University. His team's hypothesis for the

differences between hemispheres, the old world had large domesticated animals. And that, they say, was a game changer.

Because if you have a team of oxen available, then you can farm much further from your house,

and you can also farm much more land, and you can probably raise your income quite dramatically.

That sort of farming's land hungry, he says.

So over time, landowners with beasts of burden got richer

at the expense of landless peasants.

The studies in the journal Nature.

Kohler says it's harder to scrutinize the holdings of the wealthy today

...