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.

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

This is Scientific American 60-second science. I'm Julia Rosen. How much colder was it at the peak of

the last ice age? That's a question scientists have been trying to answer for decades. And now they

have a new best guess, 11 degrees Fahrenheit. That's a lot, especially considering it's a global

average.

Parts of North America were much colder.

First of all, large areas of the northeast were completely under ice, so that would have been pretty chilly.

It wouldn't be living there.

But even here in the West, right, where we weren't covered by an ice sheet, it would have been something like 20 degrees Fahrenheit lower.

Jessica Tierney, a paleo-climatologist at the University of Arizona.

Tierney and her colleagues spent years compiling information about Earth's climate at the height of the last glacial period, about 20,000 years ago.

So we obviously don't have thermometers in the glacial period.

So we have to instead look for these kinds of stand-in indicators. One kind of stand-in is plankton that lived in the ocean and got

preserved in marine sediments. Scientists use these fossils to infer past ocean temperatures by

studying changes in the chemistry of their shells and in the kinds of fats and

other compounds they produced. Tierney and her team then combine these data with a climate model

to give a full picture of glacial conditions.

It's actually a technique used every day in weather forecasting. What's new is we're using

...