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

Science Magazine Podcast

Science Podcast

News Commentary, News, Science

4.2 • 791 Ratings

🗓️ 30 October 2025

⏱️ 44 minutes

🔗️ Recording | iTunes | RSS

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Summary

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. Learn more about your ad choices. Visit megaphone.fm/adchoices

Transcript

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0:00.0	This is a science podcast for October 30th, 2025. I'm Sarah Cresby. First this week,
0:08.3	staff writer Paul Busen joins us to discuss how understanding the physics of how sound moves through
0:14.4	water can help detect ocean acidification. Next on the show, we visit the lab of Allison Moultrie in Lohia, California,
0:23.0	where he grows human brain organoids. These are multicellular structures that function a bit like
0:28.8	underdeveloped human brains. He used these organoids to explore differences between us and Neanderthals
0:34.9	when it comes to how we handle lead exposure.
0:38.0	Finally, stay tuned for the last in our six-part series on books exploring the science of death.
0:43.1	This month, host Angela Saney appropriately talks with astrophysicist Katie Mack about her
0:49.0	2021 book, The End of Everything astrophysically speaking.
1:01.8	Rising carbon emissions are pushing more and more carbon dioxide into the oceans, making them more acidic.
1:05.6	How much more and where is not so easy to figure out.
1:33.0	This week in science, Safrider Paul Vucin reports on an approach to measuring ocean acidification that focuses on the physics of sound as it travels through water. Hi, Paul. Welcome back to the show. Hi. Good to be here. So what are some of the complications of trying to get a reading of the pH of the ocean? It's something we can do. We've been able to do it, you know, if you have a little piece paper. Yeah, the right instrument and you can be there to put the water in your kind of instrument problem, of course, is the ocean is large and we do not live in the middle of it.
1:39.6	We've often relied on kind of ship collecting campaigns or point measures at single stations and remote
1:45.9	areas like off Hawaii. More recently, they are now kind of instruments on robotic floats
1:51.8	that can measure pH in the ocean remotely and beam it back. So there are different ways to get at it.
1:58.0	But there are depths to the ocean.
2:01.3	Yes.
2:03.6	There are vast spaces in the ocean.
2:08.0	This is something that comes up actually a lot when trying to study our huge bodies of water,
2:10.8	is that there's just so much to cover how to monitor them all,
2:13.4	how to make maps of what's happening underneath them.
2:13.9	It's not easy. You know, our kind of measures for acidification are very much about the surface
	...

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