Would our ancestors have benefited from early neanderthals making fire?

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Hello and welcome to Inside Science from the BBC World Service. In a corner of England 400,000 years ago, a bipedal ape made a spark. made a fire and kindled a new course for humanity. But this, the earliest evidence of human fire-making, revealed this week, did not come from our human lineage. It came from Neanderthals.

What do we take from that? And our global science watcher Roland Pease has had his head turned this week by plants that attract pollinators, not with a pretty flower, but with a warming glow. Talking of different approaches to reproduction, should we be genetically modifying our domesticated salmon so that they stop having sex altogether? And I'm joined by Lizzie Gibney.

senior physics reporter at Nature, to review the week in the journals. Lizzie, what do you have for us? We have something about just how persuasive chatbots can be and why that should worry us, and some tantalising hints of dark matter. Excellent. I look forward to being tantalised. Now, it was a turning point, perhaps the key turning point in human history. In a clay pit in Suffolk 400,000 years ago, some humans took flint, struck it with iron pyrite. and made sparks.

Though sparks landed on kindling, the kindling caught light. Here we have the earliest evidence of humans creating fire, of making and controlling the substance that would define our species. But... And here is the catch. This was not our species. It was not even really our ancestor. It was our cousin. It was early Neanderthals. Once again, a species of hominin long derided as nasty.

Brutish and stupid has surprised us. Dr Rebecca Rag Sykes is an honorary researcher at the Universities of Cambridge and Liverpool and author of Kindred, Neanderthal Life, Love, Death and Art. Hello, Rebecca. Who are these homonyms who made fire? Probably the ones we're looking at here are sort of...

the immediate ancestors of Neanderthals or even proto-Neanderthals at this point. Who are Neanderthals? How do they relate to us? It's a bit messy actually now. Sort of the past 10 years or so have shown us that... We used to sort of suggest that they were our cousins. But now, after several years of increasing evidence from genetics that shows that...

Our early ancestors, early Homo sapiens, did actually enter Eurasia a lot earlier than we used to think and were sometimes encountering Neanderthals. So there's a little bit of interbreeding too. And talk to us about the findings in Suffolk this week. How do we know that they were making fire and what does this mean? It's a really fabulous piece of work, actually. It's very, very difficult.

to find evidence for fire in the archaeological record, especially the further back you go. Okay, so you might look for burnt bones. burnt ash but you don't always get those things depending on the kind of soil and in this site there isn't sort of burnt ash or anything what the team have found evidence for is an area of burnt sediment

So reddened, and they've used four different techniques to identify that this was properly heated. It was sort of different to the surrounding sediment. They're using magnetic analysis and geochemistry to show that there was some burning. of wood going on in itself that's interesting

But they've also got a lot of burnt artefacts, so burnt stone artefacts, which are very distinctive. They're all cracked and actually shattered some of the tools. But then the icing on the cake are these two little pieces of iron pyrite.

If anybody is bushcrafty, they will know that you can use iron pyrite to start a fire if you strike it against flint. So iron pyrite does occur naturally, but not really in this area at all. So these little pieces... were probably brought in by the hominins, only Neanderthals who were using this area.

And so there'd be a neat story we could do here. We could say, you know, this is the technological turning point of humans. We've got fire. We've got, you know, the Industrial Revolution. We send rockets to the moon. But the... The fly in the ointment, which makes it fascinating, is, as you say, this is a parallel lineage. This isn't Homo sapiens. This is something else.

So Neanderthals have their own history, right? This is early Neanderthals. Neanderthals then go on for another 300,000 years doing a lot of other stuff. Eventually, about 100,000 years after this site, we see... the emergence of birch tar, which is a glue that you get by cooking birch bark. You have to do it without burning it, so you don't want a lot of oxygen. That's actually really complicated in a technological and a cognitive... sense so sort of being able to see here

that we have hominins who are already able not only to control fire, but to make it at will. That's really important for this later development of all the complicated, interesting things that we see Neanderthals doing. Tell us anything about our own evolution. I mean, I wonder how it would have felt. Do you ever think what it would have been felt as a Homo sapiens to arrive in Europe and meet this other group of humans?

and see something else that's clever and making tools and doing interesting things. Well, yeah, I mean, that would be much later than what we have here. So the earliest sort of evidence we have for some kind of... presence in Eurasia of Homo sapiens is around about 200,000 years ago and that's based on genetics and some possible skull finds as well um but yeah the whole the whole question of what what did it mean to encounter other creatures which clearly were a kind of people

What did that look like? How technologically recognisable were they? I think they would have found many, many sort of shared elements of how they lived. Equally, for example, coming into Eurasia, the plants are different, the environment's different, the animals are a bit different. So some of the species that were in Eurasia, Neanderthals. Denisovans who are over in eastern Eurasia, they may actually have had a lot to teach some of those Homo sapiens groups coming in, in terms of...

you know, what plants are nice, how to make birch tar a really handy glue, sort of pyrotechnology in that sense as well. So I think... the story of how those populations met and what that meant to each other is really interesting. But fire actually comes into that too because one of the really... The obvious things people think of with fire is it gives you heat and it allows you to cook stuff and maybe work different materials. But fire also gives you this unique social arena.

that extends social life into the darkness in the evenings. And there have been lovely studies on the things people tend to talk about around campfires are different as well. fires and hearths may actually have been a really important part of that story in terms of how these populations are interacting. Dr Rebecca Regsikes, thank you very much indeed. Lizzie, what did you make of that?

I thought it's fascinating to think of the effect that fire would have had. Like, you know, when I first thought about it, it was about like cooking and, you know, more meat, smarter brains, but actually that chatting around a fire and how that can develop. populations socially, I thought was fascinating. A quick reminder, you're listening to Inside Science from the BBC World Service.

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Time to see what curious blooms our global science correspondent Roland Pease has been sniffing this week. Colourful. fragrant flowers may cheer you and me up but their job is to attract insects in the hope they will pick up pollen and carry a little to the next bloom and fertilise it but there is another way of Pollen promotion described in Science this week. Warmth. It's an approach that evolved before flowering plants did, and it survives in cycads whose seeds sit exposed on fleshy cones.

It also evolved before bees did, when beetles were the ones doing the visiting. The work comes from the molecular biology lab of Nick Bologno in Harvard. which was approached by Wendy Valencia Montoya with a question about plant thermogenesis, heat generation, something I'd never heard of before.

Yes, that's just extremely crazy because we usually think that getting hot was something that mammals or birds did and animals like us, but not something we associate with plants. But in fact, these plants are heating. up and they are heating up a lot because they can go up to 30 Celsius above ambient. So you can actually feel this? If it is very hot, you can actually touch them and feel that they are hot. And the interesting thing is that they are doing this by revving up.

up their mitochondria, so the same structures that we use to produce heat. These are the power packs. Yeah, these are the power packs of the cells. the ones that make energy but when you are producing heat you or also a plant what they do is that they use sugar to produce heat instead of producing energy so it's basically doing it the same way

As animals do it. I mean, Nikko, have you heard of this before? I hadn't heard of it before when Wendy came. And as she said, she comes from a neighboring department that focuses on evolutionary biology. And as we are often open to new and unusual biology, when she told me about it, I was really excited for her to start in the lab to try to figure out not only what is the molecular basis of how the plants heat, but then how do the beetles actually...

actually sense and use that information for pollination. So this is not just about the plants then, Wendy. This is, you're saying, some way that they talk to beetles? Yes, exactly. So they're basically communicating with beetles through heating up. particular times and also through producing scent. So this is one of the oldest forms of communications between a plant and an insect, which is quite remarkable.

Just talk me through that. I mean, was this known before or did you think, hang on, this is something going on here and you worked it out yourself? So the fact that plants get hot was discovered a long time ago. But people usually thought that this was more associated with volatilizing sense.

or just warm shelter for pollinators. So what we did here is that we directly tested for the role of heat and infrared in attracting the beetles. So we did these cool experiments when we have... plastic models of the cones and we artificially heated them and we observed that the beetles came and visited these cones so we could isolate different signals and come to the conclusion that it was heat what they were using to visit and find the plant. Hang on, I've got to go through this.

So these plants, I mean, are they warming up in specific places? Yes. So these plants warm up only the reproductive structures. So in plants that are old, like what we started, cycads, they heat up their cones. And in ancient... flowering plants they heat up the flower so yeah these are the only structures that have been found to produce heat.

And that's what we thought that they were related to pollination. And it's also a lot of energy that they use. I mean, that tells you, Nick, I guess, in evolutionary terms, this is important if they're expending energy. Yeah, so it seemed important. And what was new and different?

Wendy did was this series of field experiments. How these looked like is the plant's heat, that's been known, but she did these simple but clever experiments to monitor whether the plants were heating and when they would heat, and they heat. actually in a very consistent pattern under circadian control, which means that they always heat at certain times in the day. So the male plant heats first, and this is followed a few hours later by the female plant heating.

So this was already telling that this might be relevant to something like pollination because they also heat in the evening when the beetles come out. And then what she did was she painted the beetles with a fluorescent marker so that she could monitor whether the beetles...

would visit at the time in which they would heat. And that seemed to correlate very well. And the timing's interesting. So beetles, I guess, like to be out in the dark. It's probably safer for them. But this is a way that they can find the pollinating parts. Right, in the dark. In the dark. Yeah, without us what we would typically think of like color.

The other thing, Wendy, which I think is amazing in this, is you didn't stop with the plants and the behaviour, but you then went to find out if the beetles actually had specific ways of sensing this heat. Yes, so we had some idea that the antennae... may be important. So we did a series of very sad experiments. We cut the last part of the beetle antennae. And when we did that, the beetles lost their ability to sense infrared.

which indicated that we have found like the locus of infrared sensation. So you're saying that on the end of their antennae they can sense the heat. Is this by touch or actually are they feeling that sort of heat radiation? That's actually very interesting because we found both. So I found neurons that were more feeling like changes in heat and others that were responding to heat from afar. And this is infrared. And we know that this mechanism is very similar to how snakes sense the heat.

So they have these proteins that are so sensitive that again, small deviations in heat are picked up by these proteins. And that is how they can sense heat, even if they are not touching something. from the distance. And Nick, one of the things that I love about this paper is you're saying this goes back way before the flowering plants to the Permian, so nearly 300 million years ago. So this is, in evolutionary terms, a...

pretty ancient kind of mutualism between beetles and these plants. Yeah, and one cool thing Wendy did, in addition to tracing the traits through fossil record and looking across colourful plants, is she uncovered... molecules, both for the plant and how the plant generates heat, and then also the beetle and how the beetle senses the infrared. And both of these... molecular programs are very old. And so all of this evidence sort of converges to tell us this signal, infrared.

was among the first pollination signals that predates the diversification of color in plants and the diversification of opsins, the proteins that sense different light spectra. And they're animal pollinators. Yes, very interesting because what we found is that when plant spirits had pollen, when...

Plants first had this need of having something that helps them carry the pollen. Among the few animals that were around, at least insects that were quite diverse, were beetles. But beetles are very bad at seeing. and they are also mostly nocturnal, so a system based on color will be pretty useless. So it makes sense that some of the earliest signals that evolved was something that tapped into the sensory systems of beetles, like heat.

So imagine, this is the oldest pollination mutualism on Earth, going back more than 200 million years. And we have the same descendants of plants and the same descendants of beetles. So this has been going on. uninterrupted for hundreds of millions of years. So it's definitely very effective. Wendy Valencia Montoya and Nick Bologna illustrating really the curious but powerful random walk of evolution.

Far more inventive, in my opinion, than any intelligent designer could be. Merry Christmas. And to you, Roland. Now, to the great salmon escape of 2025.

It was October. Storm Amy battered Scotland. On the peaks, winds gusted to 100mph. Below, rivers flooded, trees toppled. And in Loch Linney, the salmon were waiting. When waves tore through the farm's sea pens, 75,000 sought freedom, fleeing into the open waters of Loch Linney. This was good for these salmon, but was it good for salmon kind, or specifically for the wild salmon they then bred with?

Cardiff University's Dr William Perry, who studies the Atlantic salmon, explains why releases like these could have a lasting impact on our wild fish populations and whether we should genetically engineer our food... for the sake of the environment. In 1971, Jacques Cousteau, the father of ocean conservation and co-inventor of scuba equipment, made the following prediction. We must plant the sea and herd its animals, using the ocean as farmers instead of hunters. And boy did that come true.

In 2022 for the first time in history more fish and other aquatic organisms were reared in captivity than caught from the wild in a process called aquaculture. That year aquaculture produced more than 130 million tonnes of aquatic species. Is that a lot? Well, if you can imagine the weight of a fully loaded, double-decked Airbus A380 and now think of 230,000 of these, you're basically there. Unlike the handful of land animals that we farm.

There are currently more than 700 species in aquaculture, which include fish but also organisms like mussels, shrimps and seaweed. Almost half of these species have few genetic differences with their wild relatives, meaning they aren't as well adapted to farming environments, hindering production and bottom lines. However, this isn't the case for all species. Take aquaculture's golden child, one of its most domesticated and valuable fish species, the Atlantic salmon.

Bred for fast growth and delayed maturation since the 1970s, these farm fish are now considerably different from their wild relatives. This is good for business and filling plates, but it poses a particular problem when hundreds of thousands escape. every year for example when storm amy battered the scottish highlands in october this year it tore through a salmon farms pens releasing around 75 000 farm fish into loch linney the scale of this single escape

was extraordinary. Scotland's total returning wild population is estimated to be around 300,000. So in a single event, around a quarter of that number entered the wild. Compared to wild salmon, farmed escapees have reduced genetic diversity and traits which make them less likely to survive in the wild. But if farmed salmon are so poorly adapted to life in the wild, surely they'll just become seal food? Well...

Most do. But despite the odds, a fraction of these fish survive and interbreed with wild populations, bringing with them maladapted versions of genes that make these wild salmon populations less fit and able to deal with environmental change. In studies of some Scottish and Norwegian rivers, 10% or more of salmon caught are from farms, with the highest numbers found near intensive farming areas. And this comes at a crucial time.

when wild Atlantic salmon populations are seeing declines across the North Atlantic as they face pressures such as climate change, habitat loss and pollution. In the UK, they are already classified as endangered. So, what is the solution? Can we breed our way out of this problem? Selective breeding or artificial selection has made the salmon industry profitable and productive.

But this process, which changes a population's genetics by breeding only the most productive fish over many generations, is slow and inexact. And in the battle to prevent endangered wild salmon interbreeding with farmed salmon, we don't have any time to waste. The solution, I argue, lies with genetic modification. As well as achieving faster growth, genetic modification has been used to make salmon sterile which would prevent interbreeding.

You simply knock out the genes needed to make reproductive cells and sex steroids, a far more elegant solution than that implemented in Jurassic Park. If all farmed fish were engineered in this way, it would prevent the genetic pollution caused by escapees and protect our natural ecosystems. But if you look how long it took the first genetically modified salmon to get to market, we could be in for a long wait.

It took two and a half decades of battling with regulatory systems to sell these fish to Canadian markets in 2017, the salmon in question gaining just one extra gene from another salmon species. Progress in Europe is even further behind the curve. The EU has some of the greatest restrictions on gene-edited food in the world, and it was only in 2023 that restrictions were slightly relaxed in England, though not for animals like salmon.

As there is a push to domesticate more fish species to improve food security for a growing population, genetic modification could not only help make aquaculture more productive it could also protect natural populations and their genetic diversity. However, as the story of the Atlantic salmon shows, this is an uphill battle, and future progress will rely on us rethinking our millennia-old approach to changing the genetics of what ends up on our plates.

That was Dr William Perry from Cardiff University. Do you have any thoughts about using more genetic editing in UK food?

Now, Lizzie Gibney is here to talk about the rest of the week's journal news. Lizzie, have you got anything more exciting than salmon sex? It's very hard to top. These are two studies, one in nature and science that I'm bringing you first. And they showed that conversations with AI chatbots are very, very persuasive in changing people's minds when it comes to politics, much more so than more traditional methods like political ads. And these studies also...

showed how they did it. So it's not by beautiful storytelling or rhetoric, but by just giving you lots and lots of facts and information. And then the kicker is that those facts are not always true. So the two papers... are both really big studies. One of them looked at real elections. So it got people to speak to chatbots ahead of elections in Canada, Poland and the US. And then there was this separate study in science which was looking at...

how UK voters responded to the chatbot talking about kind of hot button political issues. In both cases, they looked at how the voters opinion changed after speaking with the chatbot. And the chatbot had been designed to push the opposing stance to what the voter had said. So if they liked one particular candidate, this was plumping for the other.

The results varied a bit by country, but the big take home was that the chatbots really were very persuasive and actually quite shocked the researchers like the extent of it. So in Poland, after about five or 10 minutes, you know, back and forth conversation with the AI model.

People switch their preference so that they had to give their preference for a candidate out of 100. And that went up by 10 points in the direction of who the chap was trying to persuade them to vote for. In things like conventional political ads, you might expect that to be about one point. There was a similar shift in the UK study as well. So it's really quite sizable. And of course, millions of people are talking to chatbots.

every day now around the world. So this is really something that it feels like we should be aware of. Wow. And the interesting thing is, I mean, from what I know of human psychology, normally if I stated a preference for one political opinion and a human started arguing with me... Twitter. I probably entrenched myself further. So it's almost a superhuman ability to change people's minds. What's your last paper?

So this is looking at tantalising signals for dark matter. But I'm going to first of all say it's exciting and then also pour... some cold water on that suggestion. So this is a study that was published recently in the Journal of Cosmology and Astroparticle Physics. A researcher in Japan used data from a space telescope, the Fermi Space Telescope, that looks at gamma rays.

rays coming at us from the universe and they found like an unexpected glow coming from the edge of our galaxy the milky way and so there's a potential that that glow could be caused by dark matter what can you remember about

dark matter Tom? It makes up 27% of the mass in the universe but the rest of it's basically dark energy and normal masses that we see around us is almost nothing. Exactly so it depends how you measure it but if we're talking about just matter and not the energy then it's about 85%.

of matter we think is is dark matter and that's because we see out there in the cosmos we see galaxies moving and the way that they move looks like they're much heavier than they should be from the matter that we can see

So we think there's something else that interacts just through gravity and it's otherwise very, very hard to detect. I mean, physicists have been looking for it absolutely everywhere for decades, looking in the sky with these big, huge vats to detect it underground. So far, absolutely nothing. So this...

glow that is exciting people it could come from if two dark matter particles collide they would annihilate kind of turn into energy and that would be in the gamma ray part of the spectrum and that could be what we are seeing the study is Looks like a good study, thorough analysis, but I think we should be very cautious about it. Is this the cold water?

This is the cold water. Here it comes. Well, for two reasons. So one, to see a signal, you need to be comparing it to something else. If it's going to be unexpected, what do we expect? That's actually really hard to model exactly the level of gamma rays that we should be seeing from the universe. You know, they're produced by all different...

kind of cosmological phenomena and so it's very hard to know what we should be comparing against the other thing it doesn't really explain in this paper is if this is a signature of dark matter why we're not seeing it coming from elsewhere like there are other kind of places in the universe we think that dark matter should clump and we haven't seen this same glow coming from those places. Okay so something very cool might be dark matter but we definitely haven't solved the problem.

Yet. You know, we should check it out, but I would not hold my breath. Everyone, hold your breath till next week for Inside Science. But for now, that's it from us. It is goodbye from me, Tom Whipple, and goodbye from Lizzie. Goodbye. Hello, it's Ray Winstone. I'm here to tell you about my podcast on BBC Radio 4, History's Toughest Heroes. I've got stories about the pioneers, the rebels, the outcasts who define tough.

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