Skull rewrites story of human evolution; Autism and Tylenol; discovery of wind coming from black hole

0:28This episode is brought to you by Accenture. Today we bring you analysis of an ancient skull found in China suggesting the tantalising possibility that ancestor X, so that's the shared ancestor of us, Homo sapiens, the Denisovans, and the Neanderthals, the common ancestor of those, did not live in Africa, but instead somewhere in Western Asia, maybe in the Middle East. Yeah, this could upend that whole traditional out of Africa narrative. It would mean that key stages of our evolution occurred in Asia and then returned to Africa and then later emerged out of Africa again 60 ,000 years ago rather than us doing all of our evolution in Africa.

1:06Huge if true. Huge. We're getting into that today. Also on the show we hear from medical experts on the misleading claims made by President Trump about paracetamol and autism and we have the news that we have finally discovered cosmic wind coming from the black hole at the centre of our galaxy. Finally! Yeah, and wind can get out of a black hole. It's not... light can't escape, but we're going to get into that. We'll explain that. Yeah, that's coming up. I'm Dr Penny Sarsha. And I'm Dr Rowan Hooper. Welcome to the world, the universe and us. So we're going to start with this intriguing skull found in China.

1:38The claim is that this skull pushes back the origin of our species by 400 ,000 years. And that's a really long time when we're talking about human evolutionary history. To talk about it with us, we've got science writer Michael Marshall. Mike, hello. Hello. This skull is about a million years old, isn't it? And it used to be classified as Homo erectus. That's one of the earliest members of our family. But now it's been reclassified. Can you take us through it? Yeah, sure. So this story actually goes right back to the tail end of the 1980s. So in 1989 and 1990, two partial skulls were uncovered.

2:14And they were in a terrace like above the Han River in central China. And both of these skulls had been crushed. and sort of squashed while they were underground so they were kind of deformed and damaged the second one which is called yun shian 2 was the less badly affected of the two using more recent techniques in 2010 a team was able to more or less reconstruct it and now what's happened is that a team has gone in using even more advanced methods you know 15 years later and again reconstructed the yun shian 2 cranium using a yeah a mix of techniques including one that sort of uses CT scans and they can like digitally separate individual fragments of bone and sort of separate them from the surrounding like rock and sediment that it was buried in.

2:57I'm really pleased to hear this because I remember reporting on it a while ago about this method of CT scanning and then 3D printing stuff without even having to dig it up and it's a great mix of like modern technology improving on an old technique. But Mike, go on, they've restored it and now what are we getting? So the key thing is what species does this this cranium belong to? Because it's about a million years old, 0.94 to 1.1 million, it's about a million years old. Generally when you're thinking of hominins of that age from China you're often thinking about Homo erectus. That's one of the earliest members of our genus Homo.

3:38Evolved in Africa sometime around about two million years ago and then spread out all through southern asia all the way to indonesia famously to java and survived there until a little over 100 000 years ago you'd think that maybe it's this was a homo erectus and in fact that reconstruction in 2010 suggested exactly that but the new analysis says no it doesn't it just doesn't fit um the homo erector's profile that the nose is wrong uh it's the the brain size is just too big there's a there's a bunch of things that don't really fit so what these researchers did it's to compile 56 other hominin fossils and sort of compare it on as many different measurements and traits as they could to see how that how it fit into this sort of you know existing group of fossils and putting them all together they reconstructed a family tree sort of showing how all of these different things are related to each other just based on how similar are they you know if two things look if two fossils look more or less alike they're probably quite closely related If they're really different, they're probably distantly related.

4:37What fell out of that is three major groups, and that includes most of the fossils from the last million years or so. One of those groups, Homo sapiens, modern humans, us. The second one is the Neanderthals, who famously lived in Europe and Asia for hundreds of thousands of years until disappearing just maybe 40 ,000 years ago. and the third one is this very sort of mysterious group called the Denisovans from eastern Asia who we've only known about for 15 years and what we see from this this new study is that the the Yun Shan II skull seems to be a very early like ancestor of a Denisovan or a Denisovan like hominin it doesn't fit the other two groups it's it's in the Denisovan group.

5:22So how does that change our understanding of things then if if all of those skulls from the course of a million years roughly split into these three groups does that massively push back the divergence then of of humans from neanderthals and denisovans yeah it's the age of yun shan too that really um sort of puts the cat among the pigeons in terms of like reshaping the story so the the conventional story that's come out of the analysis of ancient dna from neanderthals and whatnot is that there was this ancestral group ancestor x that gave rise to homo sapiens neanderthals and denisovans and that group sort of broke apart something like 600 000 years ago more or less and gave rise to these groups with like our group being the first one to break away and then and then there's like this intermediate period where there's neandersovans like the ancestors of the other two groups and then that group splits as well and that all happens sort of around about 600 000 years ago but in this version based on this analysis instead it all it all happens much earlier over a million years ago so the initial split is around about 1.3 million years ago and also the order of the splits looks a bit different so instead it looks like the neanderthals break away first and so you have this remaining group that's the ancestors of us and the denisovans and then that splits a bit later not not much later i have to say it's a fraction of a million It's a fraction, you know, so I'm slightly sort of cautious about that.

6:51But at least that is what fell out of the data is that the Neanderthals broke away first. But I think the really key thing is how early this is. You know, it's hundreds of thousands of years earlier. So, I mean, this is coming from an analysis of skulls, which is, you know, how we've always tried to understand human evolution. And like you say, with the Denisovans, much more recently, there's been this shift towards DNA evidence and using those tools. I'm kind of surprised, actually. Normally, like, DNA evidence suggests things are way older than there's any fossil evidence of. But this time, it's the other way around.

7:23The fossils are suggesting something happened much earlier than the DNA currently suggests. Yeah, it does. There's sort of two questions that immediately arise from that. First of all, is the fossil evidence sort of really telling us the right thing? Because they do seem, on the face of things, to be contradicting each other. There are some hints from recent genetic studies of like earlier divergences and like earlier splits happening, particularly in the homo sapiens population. There's evidence of like a split into two populations like one and a half million years ago. And then later on, those populations sort of come back together and interbreed.

8:01And we don't really know how to sort of fit all of that together. But certainly if you sort of take this at face value, then what it seems to imply is that there's a very long period when we're sort of missing a load of fossils. If the Homo sapiens group sort of splits from these other two groups 1.3 million years ago, that leaves basically a million years of missing fossils until we get to the oldest known Homo sapiens fossils 300 ,000 years ago in North Africa. and we're not quite sure what to look for or where they would be. So Mike, one of the researchers on this paper is Chris Stringer at the Natural History Museum in London here and when you spoke to him for this story and when you were talking with him you asked him what it meant if these groups were already splitting from one another that long ago, more than a million years ago in China, what does that mean for this narrative we've all grown up with that we came from Africa?

8:58and here's Chris on that. Ten years ago I would have said that probably Africa is the ancestry of most of these groups and it's sort of pumping out these different forms so the Neanderthals, Hydebergensis they may all ultimately trace their origins back to Africa. Certainly Sapiens does in the more recent past there's no doubt there was an out of Africa event maybe 60 ,000 years ago which gave rise to all the variation pretty well of humans today outside of Africa, with a little bit of addition of interbreeding, of course, with these other groups. But the main variation, we're mostly out of Africa in terms of homo sapiens.

9:37But if we go back a million years, where did the ancestor live then of us and Denisovans, Longhi, and us and Neanderthals? And what our analysis suggests is that there is certainly a big question mark over whether it was Africa. Well, that's kind of stunning, isn't it? that it can rearrange our whole narrative? Or is that, you know, from your expert point of view, is that not entirely surprising, Mike? Sort of yes and no. So as Chris said, it is still true that our most recent ancestry is from Africa. You know, 60 ,000 years ago, there's this migration out of Africa and that gives rise to all the populations all around the world, whether it's indigenous Americans, Europeans, indigenous peoples of Southeast Asia.

10:23they're all coming from they all have that sort of same uh out of africa ancestry at the same time i've been sort of thinking for quite a long time about like who would who is this sort of ancestor x you know this this group that gives rise to homo sapiens neanderthals and denisovans and it hasn't really made much sense to me to assume that they're necessarily in africa because you have the neanderthals in sort of europe and western asia you have the denisovans in eastern Asia and then you have Homo sapiens coming out of Africa it almost to me makes more sense to say well maybe the origin point is right in the middle and that you know and this group has sort of split three ways that seems quite neat in which case that would put it as you know in Western Asia somewhere like that you know the Middle East or the Caucasus or somewhere like that you know we can't be confident about that it could it could be that it actually is Africa after all but I think the possibility has definitely been thrown wide open.

11:19What this made me think of is like how we looked at dinosaurs for many years from really from Europe and from the US and then in the last I don't know 20 years or so we've seen this boom of dinosaur fossils especially feathered ones from China and you know it started to rewrite the story of dinosaur paleontology and is the same thing happening here a little bit in that we've only just got proper sort of human evolution paleontology going on in China and that's why we're rewriting the story a bit. I think it's almost more that the story is coming full circle. When people were first investigating human evolution in the late 1800s the first famous discoveries were all in Asia.

12:03So Java Man which is the original Homo erectus fossil and in the early 20th century Peking Man which was a fossil sadly lost from China. It was only in the 1920s when the first Australopithecus fossils were found in Africa that the idea that humans and our ancestors come from Africa started to be established. And with the advent of genetics in the 1990s, we got this clear evidence of the recent out-of-Africa migration. And I think that what sometimes happened is that we've sort of sometimes over-fixated a little bit bit on the very factual and true evidence that Africa is a huge part of this story, you know, absolutely indispensable.

12:45But I think we sometimes have slightly over focused on that and kind of downplayed what's happening in Asia and elsewhere, which I think is actually is going to turn out actually also to be really important. It's interesting because for quite a long time, the story, well, it wasn't just Africa, it was East Africa. And in part, thanks to DNA evidence, we now know that actually humans were evolving all over Africa and there was a lot of mixing and diversity. And it's almost like this is part of that broader picture too, that before humans came back to Africa, there were different types of hominins and human ancestors all over Eurasia, I guess.

13:19Yeah, I think so. I mean, one of the things that Chris Stringer said to me was that we've only got fossils really from about like 10 % of Africa, something like that. It's mostly from East Africa and South Africa and from certain time periods in Africa. We've got a pretty good It's a fossil record for fairly recent members of our species, like the last 100 ,000 years ago. But the origin points, the older bits, are actually really under-documented. There's two sets of fossils from about 200 ,000 years ago in East Africa and then the 300 ,000-year-old stuff from Morocco. That's very little for 100 ,000 years' worth of evolution and mixing.

13:55That's really only three data points. And potentially even longer, because you said if we're as old as 1.3 million years, there's almost a million years of missing fossils, aren't there? Where are they? Why can't we find them? It's a very good question. One thing to bear in mind is that it's not obvious when in that time period the hominins started to actually be like Homo sapiens in the sense of actually looking like us and acting like us. When these three groups split from each other, presumably those three initial populations were pretty similar to each other and it's only later that the sapiens-like traits evolved.

14:33There's a huge chunk of Africa that's sort of very, very underexplored, particularly the center and the west. There's not actually very many fossils of the right time period from Western Asia. You know, there's loads of like fossil sites in Israel and places like that, but they're generally from the last couple of hundred thousand years. There's not very much from a million years ago at all. And there's only one hominin fossil from the whole of India, which is a massive area and there's this one skull called the nomada skull without even sort of speculating as to what happened in that region something happened in that region and we don't have anything to tell us about what it is a problem is one skull i should have you mentioned peaking man i should have remembered that because i've got a model of it in soap on my mantelpiece which i'm never going to use it's next to a model of homo habilis um so i should remember that but Mike, what is the next, at least for Stringer and this group, what are they going to plan to do next?

15:31So one of the things that they would like to do is to try to bring together the genetic evidence and the morphological fossil evidence. Because on the face of things, they do seem to contradict each other. But what would happen if you actually put them together in some sort of massive analysis? What would that tell you? Obviously, they're keen for us to find more fossils from the different time periods and locations that we talked about. sometimes when i write about a story about human evolution it sort of feels like it's sort of tied everything together and it sort of creates a really clean um narrative that i can then sort of hang my hat on for ages this feels more like kicking open a door and discovering that there's this whole labyrinth of other corridors that we didn't know that we were going to have to go walking down um love it and that yeah it feels like it feels like there's a whole bunch of new stuff that people will now have to go and look for on the basis of this how do you manage a virtual power plant connected to 300 ,000 devices and with a 2 gigawatt capacity.

16:26It's a massive optimisation challenge solved with sophisticated data science that's already operating in the UK today. At the same time, it's increasing the resilience of the energy grid as our energy mix becomes greener. Find out about the cutting-edge technology behind the virtual power plant on the New Scientist CoLab podcast, sponsored by Octopus Energy. And hear Octopus expert, Kieran Stopforth, explain how electric vehicles are becoming crucial components of the energy grid, how partnerships with home builders can make green energy essentially free, and how decentralised control systems are creating a smarter, more robust energy network.

17:05Find the New Scientist CoLab podcast wherever you get your podcasts. Now, the US government has been making headlines for statements around autism that are entirely unsupported by evidence and science. I saw a clip of President Trump suggesting that pregnant women with fever should just tough it out. And he repeatedly said not to take Tylenol, which is the US brand name for paracetamol. And here's a clip of him. Don't take Tylenol. Don't take it. And don't give it to your child after your child is born. He said don't take Tylenol repeatedly over and over again. We've got our health reporter Grace Wade here to discuss this with us.

17:45Hi, Grace. Hi. So on Monday, we had this announcement from the administration, and they also announced two changes pertaining to autism. And can you explain what they are for us? Yeah, so the first is it will be updating labeling on the common painkiller paracetamol, which in the U.S. we call it acetaminophen. And the medication will now carry a warning that use of it during pregnancy may increase the risk of neurodevelopmental conditions in children, such as autism. And then the second decision was to approve a drug called lucovorin for a subset of children with the condition. And what was their attempted justification for this?

18:22Yeah, so since Donald Trump took office and appointed Robert F. Kennedy Jr. to lead public health policy in the U.S., the administration has made it a goal to tackle what they call a crisis of autism or the autism epidemic. And earlier this year, RFK Jr. vowed to identify the causes of autism by the end of September. So, you know, we're almost at the end of September here. So I suspect that is why those initiatives were made. Yeah, I mean, so many things wrong with that, aren't there? We'll start by saying there hasn't really been this autism crisis wave that they're saying there is. We've said before, while autism rates are rising, it's almost entirely explained by increasing better diagnosis.

19:05Yeah, expanded definition of the condition and also better recognition of it in individuals. Awareness and all those things. Yeah, you are absolutely right. And even if there was this so-called autism crisis, these two initiatives are highly unlikely to have a significant impact on autism rates. You know, for instance, the research on paracetamol and autism is mixed. Some research, including a meta-analysis of 46 studies, has shown an association between paracetamol use in pregnancy and an increased risk of autism in children. But, you know, just because there's a relationship doesn't mean paracetamol causes autism.

19:41other factors could be at play. Right and we other factors we actually know about are genetics right that's a that's the big primary factor that we know about isn't it? Yes absolutely so another study of nearly 2.5 million children found that those who were exposed to paracetamol during pregnancy did have a slightly higher risk of developing autism but this effect completely disappeared after comparing children exposed to the painkiller with their unexposed siblings. So that's genetics then, that hints at a strong familial basis? Yes. So it really is dangerous then to issue this warning given that evidence that's very nuanced, it doesn't show a causative link.

20:17I also know in pregnancy you're told to avoid all kinds of things because of hints or suggestions. But there's a real risk to telling people that they can't take paracetamol during pregnancy. It's the only widely available medication for treating pain during that time and in particular fever. and fever during pregnancy can have really severe effects and should be treated. Exactly. And the FDA acknowledges this. In a letter to physicians, it noted that paracetamol is still the safest over-the-counter painkiller for use during pregnancy, and that if left untreated, high fevers during pregnancy pose a risk to the fetus.

20:51And just to echo what Penny just said, to emphasise how irresponsible and dangerous this sort of fact-free statement is. We reached out to Arthur Kaplan. He's head of the Division of Medical Ethics at NYU Grossman School of Medicine. And here he is on this. Well, I thought I had never seen a public event by people claiming to be authorities on medicine and science that was so dishonest, disorganized, misinforming and dangerous. I thought the discussion of autism was a public health disaster and even I'd go forward to say a menace. First, they decided to target Tylenol and its use by pregnant women as the cause of autism.

21:40There is no data to back that up. There are some few studies historically that show there might be a correlation. but as anyone who's looked at such things knows there are many things that correlate together that don't turn out to be causally related. The studies that have attempted to determine causation have come up negative including a big recent Swedish study involving many many many women and kids to announce on the basis of the evidence available that Tylenol is a cause or the cause of autism is the height of irresponsibility. It also came up during the meeting. Trump kept saying, don't use it, stay away from it, and in fact, advised pregnant women with fevers literally to tough it out.

22:26That is morally irresponsible. It is blaming women who take Tylenol when they have high fevers or pain in a way that is inappropriate. and moreover it defies medical recommendations from every medical group, Maternal Fetal Medicine Society, ACOG in the US, many groups overseas who know that fever is demonstrated to be dangerous to fetuses. We have no doubt that that is a problem. So a public health disaster, a menace, fear-mongering for pregnant women. I also spoke with Gretchen Goldman. She's president of the Union of Concerned Scientists, Union of Furious Scientists at the moment. And here's what she said.

23:13The president's disinforming comments fly in the face of decades of evidence and scientific consensus, and they threaten public health across the country. Medical advice should be informed by the best available scientific information from qualified professionals. Yet under the Trump administration and Health and Human Services Secretary Robert F. Kennedy Jr., disinformation has been given a prominent platform. It's truly heartbreaking to know that these actions will put children, pregnant people, and vulnerable groups in harm's way. And this is happening at a time when we should be focusing on improving the lives and the health of everyone in this country.

23:55So what about the other initiative that was announced then, this drug called lucovorin. I hadn't heard of that before. Well, that's probably because research on lucovorin for autism is still in its infancy. This drug is a form of vitamin B9, and some research indicates that upwards of 40 % of people with autism might also have a condition called cerebral folate deficiency, which that prevents uptake of vitamin B9 in the brain. So is the idea then that by providing this drug, it ups those vitamin levels and that could help with autism symptoms? That's the idea, but it's too soon to say if that's actually what happens.

24:31So, you know, some small studies in children with autism have shown that those who take the drug are more likely to see improvements in severe autism symptoms, especially those that affect verbal communication, than children given a placebo. Yet the effect is small and Leucovorn is by no means a cure for autism. So essentially both of these initiatives then lack the kind of extensive scientific backing you'd normally expect for these big kinds of pronouncements and will probably have no impact on the rates and incidence and severity of autism. Exactly. If anything, they just sow more confusion about how to safely treat pain and fever during pregnancy.

25:11I mean, what's been frustrating about how this is reported is how it's almost taken seriously. And we've seen this with climate change over the years, you know, having to both sides an argument. But there's no both siding an argument when people just don't know what they're talking about. And there's an agenda here, isn't there? I mean, we don't know what's going on in RFK Jr.'s head. But it does seem like this is part of a campaign to disenfranchise women, blame women for autism, just like the administration is trying to restrict women's freedom in other areas, reproductive freedom, prevent access to contraception and abortion services, things like that.

25:51It just seems like part of a bigger campaign. And that's something that is not being reported. You can't really get a handle on it. But that seems like that's what's there. It also concerns me that once an idea like this is out there, like the MMR vaccine on autism, which has been hugely debunked for a really long time, that's still causing preventable deaths by measles now because there are some people who are still concerned about what the MMR vaccine does, even though we know it's safe. So now that's out there, how on earth do you bring it back in? Well, that's why I wanted to talk about it today.

26:23And that's why to echo what Arthur Kaplan said, this is a public health disaster and a menace. Absolutely. I mean, I think something that's been really troublesome about the Trump administration is that the things Trump says differ actually from what his, you know, the FDA or the HHS, these public health organizations that he's leading. It differs from what they end up putting out. But, you know, people are going to listen to the president. They're going to hear what he says during press conferences. They're not always going to read the physician letter that the FDA sends. now to turn to the mysterious black hole at the center of our galaxy Sagittarius A star and the discovery that it's more active than we thought we know almost all galaxies have a supermassive black hole at their center but we actually know surprisingly little about the one that's at the center of our galaxy it's a long way away isn't it it is like you know it's kind of important yeah kind of personal i think we all probably remember when the event horizon Telescope produced that iconic image in 2022 of the donut shaped structure of our black hole.

27:25It was a really big deal because it was so hard to observe. And why is that? Alex Wilkins, you're here to tell us more. Yeah, as you say, that felt like a really huge moment. We'd never seen anything even resembling a black hole in our own galaxy. And that's because it's so hard to observe. So the centre of our galaxy is a very chaotic place. There's a lot of stuff going on. and there's gas, there's hot dust, there's stars kind of swirling around. And that makes it really hard to see this thing 30 ,000 light years away. The actual region itself is only a couple of light years apart, and the event horizon of the black hole is only a few tens of millions of kilometres apart.

28:00So it's really, really hard. So the donut image we saw, that's a few tens of millions of kilometres apart, that structure that we were looking at at a distance of 30 ,000 light years. Yeah, it's a kind of incomprehensible distance. and then you add in the fact that our supermassive black hole is really strangely quiet and when we look at other galaxies we see signs really often that they're feeding so you'll see these huge jets kind of being beamed out and that's how we see these black holes kind of across the universe but our black hole Sagittarius A star is not like that it seems really kind of weak and pathetic and inactive and so we've looked for kind of winds or any sign of activity for half a century from our black hole and we just haven't found anything we we do know that once it was active there are these kind of big bubbles of gas below and above the galaxy called fermi bubbles which we think are kind of fossils of past really intense beams but right now we don't see anything resembling that my daughter asked the other day if the black hole was going to devour us eventually i was saying no no it's it's silent it's inactive it's quite no no worries but now we've seen something well if if it turns on again at some point it it it could be bad for us if it shines in our direction to this podcast let's hope not um so yeah we haven't found evidence of beams turning like that but we have found evidence of winds kind of hot winds coming from Sagittarius A star so two astronomers at Northwestern University in Illinois Mark Gorski and Elena Merchikova think they found the first clear evidence of hot winds coming from Sagittarius star winds to recap are these streams of hot gas that are produced from material basically swirling around the black hole heats up a lot from pressure and magnetic fields and then it's kind of spewed outwards in various directions okay and and just if anyone's thinking well i thought nothing could escape a black hole and not even light can escape as everyone knows this is because it's not in the it's not crossed the event horizon this is the crush up at the event horizon that's creating all the stuff.

30:01Exactly, yeah. Anything that goes in can't come out again. You're right, but this has never gone in. It's kind of heated up and then come out. So they used this telescope called the Atacama Large Millimeter Array in Chile, which is basically the best telescope in the world for observing gas in places like these. And they mapped out this region around Sardicieri's A-star called the circumnuclear disk, which is this really innermost part around the black hole, has really hot gas and dust. And as you go towards the black hole, it becomes hotter and hotter. so previously we thought that you couldn't actually get cold gas in this region because it was so close it would be so hot that all you could image is hot gas and so no one even really bothered looking for cold gas but Gorski and Murchikova they kind of explicitly looked for this in the disk and they found that you actually did have a lot of cold gas in this region unexpectedly Gorski told me he doesn't know why it's there and they need to kind of find out why cold gas can exist so close to the disk but because they mapped out it meant that they could also see a really hot region this cone of hot wind blowing all of the cold gas out of the way wow and when you look at the image it does make it pretty clear but they do think this is this wind then yeah absolutely so they worked out that the energy required to blow all of that cold gas out of the way would be about equivalent to 25 000 suns and and they kind of tried to come up with alternative explanations they thought well maybe it could be from an old supernova there there are no supernovas nearby.