Detecting the acidity of the ocean with sound, the role of lead in human evolution, and how the universe ends

First up on the podcast, increased carbon dioxide emissions sink more acidity into the ocean, but checking pH all over the world, up and down the water column, is incredibly challenging. Staff Writer Paul Voosen joins host Sarah Crespi to discuss a technique that takes advantage of how sound moves through the water to detect ocean acidification.

Next on the show, we visit the lab of University of California San Diego professor Alysson Muotri at the Sanford Consortium, where he grows human brain organoids—multicellular structures that function like underdeveloped brains. Muotri used organoids to compare a protein that appears to be protective in human brains against the effects of lead toxicity with the archaic version of the protein that was present in our extinct cousins, like Denisovans and Neanderthals. His work suggests lead exposure differently affected our ancestors and our archaic cousins, possibly helping us survive to the present day.

Finally, stay tuned for the last in our six-part series on books exploring the science of death. This month, host Angela Saini talks with astrophysicist Katie Mack about how the universe might end and her 2021 book The End of Everything: (Astrophysically Speaking).

This week’s episode was produced with help from Podigy.

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