Linking cat domestication to ancient cult sacrifices, and watching aurorae wander
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This is the Science Podcast for April 18th, 2025. I'm Sarah Crespi. First this week, online news editor David Grimm is here to talk about how an Egyptian cult that killed cats may have also tamed them. Next on the show, researcher Agnet Mokopade talks about how his group mapped changes associated with a big shift in Earth's magnetic poles about 41,000 years ago and what it would be like if such a dramatic magnetic change took place today.

I always thought that domesticated cats came from Egypt, but it turns out... They came from Egypt. It turns out that the field of cat domestication has moved around the geography and the timeline of cat domestication quite a bit in the past few decades. Online news editor David Grimm is here with a pair of new studies that brings us back to Egypt, as he mentioned, as a source for cat domestication. Hi, Dave. Welcome back to the podcast. Hey, Sarah. Glad to have you. So...

I know that cats have been synonymous with ancient Egypt for a lot of people. So how far back in time do we know the relationship between cats and Egyptians goes? Yeah, I mean, you know, there is evidence for cats in ancient Egypt going back even before there was actually like an official ancient Egypt. You know, we're talking maybe 6,000 years ago in that region, but it's a little unclear what exactly those animals are. But there are paintings of cats going back almost...

4,000 years. There's a painting of a cat eating fish under a dining room table that goes back to about 1500 BCE, so about 3,500 years ago. So we've long suspected that cats arose in ancient Egypt, but that story, as you alluded to, Sarah, has kind of changed a bit over the past couple of decades.

What are some of the alternatives that have been proposed for where cats were domesticated besides Egypt? So things actually started to change in 2001, and this is actually a paper published in 2004.

archaeologists discovered this grave of a human and a cat that seemed to be buried together beneath this 9,500-year-old home on the Mediterranean island of Cyprus. And the cat is sort of covered or surrounded by these decorative seashells. And it seems like the cat's arranged in this way that he's staring into the person's eyes.

And this is 9,500 years ago. This is thousands of years before ancient Egypt even existed. And it sort of then created this theory that cats sort of arose with early farmers because this was an early farming village. And the idea is that when you have grain and grain storage, you're attracting rodents. And these cats would have slunk into these villages.

chasing the rodents and maybe known a good thing when they saw it and self-domesticated. The tamer cats would have been the ones that would have hung around and eventually evolved into the house cats we know today. And then beyond this find, there was a paper that was published in 2017, which suggested that there was, and the other papers as well, which found a few scattered cat bones in

in Europe that also seem to be dating from maybe around 6,000 years ago, maybe a little bit more recently. So this put stuff in Europe, in Cyprus, before Egypt. Before Egypt. And like kind of already spreading into Europe. Already spreading into Europe. So the idea is cats evolved with early farmers and as farmers migrated from the Mediterranean into Europe, they brought these cats with them. And again, a long time before ancient Egypt even existed. The new research that we're going to talk about today...

brings all this into question, these early European domesticated cats. What did they find out? What are these new papers? Right, this is a couple of teams. And basically what they did was they did an analysis of the bones of the Cypress cat, a really detailed analysis of the measurements. They did a genetic analysis of these bones that have been found in Europe. And their conclusion is that none of these cats are related to today's cat.

They're cats though, right? They are cats. They are European wildcats, which is sort of a distant relative of today's cats. The direct ancestor of today's cat is known as the African wildcat, gave rise to today's

And the European wildcat is sort of a bit of a distant cousin of the African wildcat, but really not at all directly related to the cats we know today. So these were likely wild animals. Maybe there was some taming going on, but really had nothing to do as far as these papers are concerned with the story of today's cats. Yeah, of our babies. So now we have to go back to Egypt and say, okay, you really did do it. You really brought us the domestic cat. Right.

Right, because once you take these cats out of the equation, then the oldest cats now become this DNA that was recovered from cat mummies that date between maybe about 500 BCE to about 0 CE. So a lot more recent. And those are...

African wildcat descendants? Genetically, they're domestic cats. And this timeframe is really interesting because now when we're talking around 500 BCE in ancient Egypt, this is around the time where you have this resurgence of this cult of Bastet. And Bastet was this very famous Egyptian goddess. She had been around for a few thousand years

But around the first millennium BCE, there's a resurgence in her popularity. And a couple of interesting things happen with Bastet. She used to have the head of a lion. Now around the first millennium BCE, she gets the head of a cat.

Oh. Also, there's these cults that arise around Bastet. Pilgrims would come to these temples and they would want these what are called votive mummies. It's sort of a proof that you had been there or a way to sort of show your devotion to Bastet. And to create these mummies, the priests or whoever ran these temples needed cats. Oh. Lots and lots of cats, potentially millions of cats. So the mummy is a cat mummy? Because Bastet had started to be linked to cats...

the mummy you wanted was a cat mummy and so people would ask for these cat mummies and became such big business it's estimated that there were millions of these cat mummies created over potentially the course of centuries and to have millions of cat mummies you need to be breeding

millions of cats. Oh, you're going to link this to domestication. Right. You're thinking about maybe cats in very close quarters. Wild cats don't like being around people. They don't like being around other cats. And all of a sudden they're forced into this environment where they have to be around tons of other cats. They have to be around people. And this, at least the authors suggest,

would have selected for the tamest cats. And when you select for tameness over generation over generation, that eventually can lead to domestication. And so one of the authors actually calls this the murder domestication pathway.

But this idea of, you know, having to raise all these cats for sacrifices, for mummies, it doesn't preclude the self-domestication happening in Egypt instead of what we talked about before in Cyprus. Well, there's a couple of reasons that this may not be true. One is, you know, I mentioned that painting of the cat beneath the table. That painting is from 1500 BCE. So we're talking hundreds of years before this cat cult really arose. And so that timing doesn't work out. And again, there are older depictions of cats in

in Egyptian art. We're not sure they're domestic cats, but it would certainly predate this cat cult hypothesis. Also, you could still have this pathway where rodents are helping to lead to cat domestication. Ancient Egypt, also big on farming, people storing grain, grain bringing in rodents. If the cat comes in, the cat's killing rodents.

People also have problems with snakes and scorpions, which cats are also likely to kill. So you can also imagine this idea that much earlier in Egypt, you bring cats into your home, that could have also selected for the tamest cats, the cats likely to be around people. And that's certainly another completely viable pathway to cat domestication.

You've written stories about a strain of cats in Asia that aren't related to domestic cats and now European cats that aren't related to domestic cats. It's really interesting. These domestication stories tend to show you just how many varieties we had to choose from when domestication came about. Right. I mean, if we accept that maybe the cypress sparrow was...

a European wildcat maybe in the process, maybe becoming domestic cats and it was just sort of a dead end. There's also evidence from a Chinese farming village, I believe about 5,000 years ago, where a different kind of cat, a leopard cat, seemed to be on the path of domestication. And yet neither of these cats, neither the leopard cat, nor the European wildcat, gave us today's cats.

It was only the African wildcat that did. So as you say, Sarah, this could have happened multiple places in the world. It likely only happened one place. And that place seems to be ancient Egypt. Yeah.

Sounds like it to me. What else can they do to shore this up? I mean, are they going to try to figure out which domestication hypothesis is more likely using different techniques? I think the how is going to be really difficult. That remains a big problem with dogs too. There's all these theories about how dogs became domesticated, but absent a time machine, it's really hard to show that. What they can hone in on is the timing. The more DNA they have, the more samples they have, the more they're likely to figure out at least...

if not how this happened, maybe when this happened. Great. Thank you so much, Dave. Thanks, Sarah. David Grimm is the online news editor for Science. You can find a link to the story we talked about at science.org slash podcast. Stay tuned for a conversation about what happened when Earth's magnetic poles nearly flipped 41,000 years ago.

Earth's magnetosphere protects us from the solar wind and high-speed charged particles from elsewhere in the galaxy. It's most noticeable to us as aurora in the polar regions, which get really big and bright green and pink during solar storms. The magnetosphere actually catches incoming

potentially damaging particles and moves them along its field lines, preventing them from hailing down on us and the rest of the Earth's surface. This umbrella of protection is created by the spinning, rotating, hot liquid core of our planet, which also gives us the magnetic poles. But we know sometimes, very rarely, those poles switch places. And a little bit more often,

The poles will just take something called an excursion, just a little journey away from the very ends, north and south as we think of it. This last happened about 41,000 years ago. We know this from magnetic traces and rocks, and we have suspicions about the impact on the planet. What happened to people, animals, weather, plants? And what would happen now?

Agnet Mukhopade and colleagues writing in Science Advances this week modeled this big change in Earth's magnetic shielding all those millennia ago as a step towards understanding the impact more broadly. Hi, Agnet. Welcome to the Science Podcast. Thank you so much for inviting me here, Sarah. I'm really happy to be here. Yeah, I was really struck by the title, The Wandering Aurora. It's just perfect. So do we know why the

the Earth's poles, why the magnetic field sometimes flips or takes these excursions away from what we think of as North and South? I think the why is the big question. We do not have a clear idea of what may have caused this, but then we do have an idea of how it evolved and what it ended up looking like or how the magnetic field evolved over thousands of years. We know that it happens, but we don't know if it's

for example, a natural thing that is like part of this dynamo

part of the process of it existing. Or sometimes Earth is hit with something giant and it causes a disruption. We have no idea, but we do know what happens. And we need to know more about that, both for our own personal safety and also to just better understand our planet. What kind of traces are there in the atmosphere, in the land, the rocks of these kinds of shifts in the magnetic pole?

poles. What happens is rocks and sediments capture much of this change in the magnetic field. In our study, we end up using many of these rocks and sediment cores

to come up with what the magnetic field looked like back in the day. So we do partially the same kind of thing today when we come up with what the global magnetic field looks like at the current point. And for an event 41,000 years ago, we basically ended up looking at the rocks and sediments of that time period and figuring out what caused this. The event itself is actually named after the Le Champs region of France, where lava flows were discovered and they were the ones which had the traces of these very

weirdly wiggly magnetic field lines that led to scientists thinking that, oh, wow, 41,000 years ago, something really, really weird happened here. Right. So as the rocks cooled, their magnetic field was, you know, aligned certain things that are responsive to that in the lava. It's wiggly. It's like, oh, how about this way? And how about this way? And you can see it's not a very long period of time when you're talking about the formation of rocks, right? How long did this event, the one that's 41,000 years ago, how long did that last? The

The exact effects of it, the local effects or things like even coming down to the modern magnetic field, that lasted for a while because it is a disturbance in the geological timeline. But the event itself, the time when the magnetic field just flipped itself and reduced by almost 10 times its value, 10 times its modern value, lasted for only a

300 years. And 300 years, like it may sound like a very huge number, but from a geological perspective, that's less than a second. It's a very significant rift in the magnetic timeline of this planet where we see that like, wow, there's this one blip where the magnetic field strength disappeared almost and the magnetic poles just switched itself up.

And this is where I would recommend people go look at the figures because you can see the magnetosphere that we were talking about at the beginning as this kind of bubble. It has a part that's facing the sun and it has a part that's away from the sun and they're different thicknesses. And then in this period of the reduction, you said like a one-tenth, it looks very skinny. It looks very thin. What did your model tell you about the deformation of this protective shell?

That's, I think, one of the most fascinating facets of this study. We did not have any expectations with this specific study in the sense that we had an idea that the magnetic field had reduced significantly 41,000 years ago. So we kind of expected that most of the changes that we would see is a smaller magnetosphere or a shrunk up space environment. So if this was to happen today, then

Basically, all our geostationary satellites or any of our long-range satellites would be outside of the magnetic field. That's about it.

What was not expected was the tilt in the magnetic pole. What our study found was that we did have an idea that the poles would have flipped or the poles would have started to flip. It didn't flip completely. That's why it's not a reversal and still an excursion. But it started to flip and the magnetic North Pole went down to almost equatorial regions. The North Pole was over East Central Africa.

and the South Pole was near Oceania, like right over New Zealand and Southeastern Australia. So basically sideways. Exactly. And the funny thing with that is that like that is something that we generally see in outer planets. So like Neptune has a magnetosphere similar to that because it's not like a rocky planet. Its magnetic field flips almost every day. And that's what we generally see as the afternoon. In Neptune's magnetosphere, the afternoon looks like what happened. It's afternoon polarity. Yes.

That's amazing. So we see a shrinking of the field of the magnetosphere and then a repositioning of the poles. That's right. What would this feel like? So we know 41,000 years ago, we had modern humans running around. We had a lot of the same animals that we have today. I guess for them, they would see Aurora in different places, the Aurora Borealis in a different place, right?

Right, right. And that was initially what our idea was. So when we started working on this investigation, it was primarily more of a space plasma investigation of finding out what happens to the magnetic field if we actually do crank it up like that. Our first result itself was that like, oh, wow, we would probably have global horrors because the magnetic field reduced to such an extent. So the biggest takeaway point from the magnetic side of the study is that the Earth's magnetic field basically

basically just stopped acting like a magnetic field. It became something what we call as a non-dipole. So a dipole is like you would actually have a north and a south pole, so two poles. But it actually became more of a multipole where there were like more than like just one pole around the earth. So

So not an iron bar with a north and a south. And you see these connections from those poles, like in these nice arcs that it's all tidy. It's more just like little spots and blisters of magnetism. So that means that it's not doing that job that we want it to do, which is

to fling these particles away from the surface. That's exactly what our study found. And with the reducing value of the dipole strength itself, what that meant was that we would have more amount of particles bombarding the Earth's atmosphere at even more lower latitudes. So basically what we predict is that during the peak of the event, when the magnetic field basically just dropped to the lowest value, early humans on the ground would have likely seen auroras almost everywhere.

And we can't say, oh, well, they were definitely irradiated. But we can say that they probably did experience more of the particles coming off the sun and more cosmic rays than we would today, you know, even if we had a solar storm, for example.

That's the anthropological side of the study where we did end up looking at if the magnetic field did reduce this drastically and it did move around this drastically, how badly did that impact things on the ground? And the easiest way to start off such a study is to look at how does a change like this impact the upper atmosphere, the lower atmosphere, the circulation mechanisms and the composition of the atmosphere? And does that end up

creating any kind of changes on the ground. We made this cool map, basically like integrating all the auroral regions and the regions where there were open field lines and where the magnetic field would have been a little bit wobbly and map that to anthropological settlements, human settlements. And so 41,000 years ago, we found a very

integrated human settlement in southern Europe, southern France and parts of Spain, cave usage became something that was much more prevalent. We found that one of the big differences between the two predominant species, the Homo sapiens, who were just evolving and the Neanderthals, a big difference between them was that Homo sapiens are

Our ancestors basically started wearing more tailored clothing, something that they had not done before. While Neanderthals, they just went with the crepes of some kind. Cave paintings became more popular. The usage of caves in general became more popular. And one key thing that led to us saying that maybe there was more UV radiation that affected lifestyle was that the use of ochre as a sunscreen became much more prevalent because there was much more usage of ochre mines than before 41,000 years ago.

This is very cool, like the idea of kind of lining this up with changes in what people and Neanderthals were doing. But it's going to be hard to ever really nail that down because we're not saying, oh, we see more cancer in their bodies or we see like more irradiated DNA. But it is very cool to try to connect these things. Now, what about the...

the atmospheric changes? Like, were there any kind of indicators that you were able to look at there? Because one of the things that happens in the stratosphere is when these particles impact and interact with the magnetosphere, it kind of like offloads some of that to chemical interactions up there. Right.

Right. That's kind of where our study becomes a projection for some other investigations, because several previous investigations have looked at the impact of reducing magnetic field on the planet's atmospheric composition. The easiest thing that would have been affected by such a change would have been the ozone layer. The ozone layer would have been bombarded by way more eutrophics.

or UV radiation or radiation of any sorts. We estimate that the galactic cosmic radiation and solar energetic particles would have basically done a number on this whole layer, which basically would have allowed much more UV radiation to seep into the seaport to the ground.

There have been some previous studies which have looked into the difference in oxygenation, the difference in nitrogen content and of like other minute particles in the atmosphere because of the reduction in magnetic field. Our study does not go specifically into that, but it does form the platform for which future studies would be driving this kind of a discussion. And bringing this forward to today, it's been 41,000 years. Is it time for another one? And if we did have something like this occur,

We have compasses now. We would see it. We have so many things that depend on knowing north from south. Would it have a big impact on humans and everything else on the planet?

Short answer would ideally be yes. The longer answer is that we are already facing something like this or would likely be facing something like this going forward. It may not be the exact or as drastic as the LeChamp event, at least modern indicators don't show that. But it's a fact that since, and I'm going to

Say 1859 is when the British started keeping global records of the magnetic field. And since then, the worldwide community of scientists have come up with what the global magnetic health looks like. We have found that over the last 150, 160 years or so, there has been a decrease in the magnetic field strength.

by almost 10-15%. The thing is that the reduction in the dipole strength itself means that space weather events would be much more pronounced today than they were, say, 150 years ago.

they would be affecting technology more adversely. All our satellites are kind of naked out there in space during the space weather event because the magnetic field is not there to protect all of them. Maybe if you are in low Earth orbit, but even then you end up getting a lot more space charging. Satellites tend to fall off orbits in the low Earth orbit because the density of the atmosphere changes drastically. These effects would become more pronounced even for medium level space weather events. Definitely there is an impact

on humans on this, because most of our modern technology, satellites, communications, transport is all dependent on all these things that are

pretty easy to break. Yeah. Do we have enough data from past versions of this event to make predictions about the speed of the decay that's happening or how complete it would be or how long it would last? Not yet. I feel like this is something that I think going forward, we would know a little bit more. Current indications just indicate more of a slowdown. There have been some movements in the magnetic

poles as well, the Earth's magnetic field is still pretty dipolar. So as of right now, we don't have to be worried. So that's good. So it should be it should be fine. Yeah. Thank you so much, Agnet. No problem. Thank you so much for your time. Agnet Mukhopade is a research affiliate in the Climate and Space Sciences and Engineering Department at the University of Michigan. You can find a link to the science advances paper we discussed at science.org slash podcast.

And that concludes this edition of the Science Podcast. If you have any comments or suggestions, write to us at [email protected]. To find us on podcast apps, search for Science Magazine or listen on our website, science.org/podcast. This show was edited by me, Sarah Presby, and Kevin MacLean. We have production help from Podigy.

Our music is by Jeffrey Cook and Wenkui Wen. On behalf of Science and its publisher, AAAS, thanks for joining us.