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The "immersive entertainment" boom takes user-centred experiences to new heights, but isn't it making culture a little insular, asksArwa Haider

What are you doing later: roaming through Van Gogh’s landscapes, time-travelling to ancient Egypt or maybe catching a posthumous gig from a musical hero? These are the kinds of “immersive” experiences we are increasingly flooded with, spanning dizzying possibilities that each promise to place us at the centre of their story. The immersive entertainment market globally wasvaluedat around $114 billion in 2024, and it is predicted to almost quadruple to roughly $442 billion by 2030.

As a journalist and life-long pop culture fan, I am simultaneously captivated and unsettled by immersive entertainment. My most memorable experiences of it were intensely personalised and powerfully emotive; they have made me exhilarated, tearful, even “cybersick”. When we are wrapped up in a narrative, particularly one relayed through a headset, we are removed from real time – arguably part of the allure.

It isn’t the escapism that fazes me, though – great culture liberates us from everyday constraints – it is the insularity. Immersive events elevate the subjective viewpoint, often at the expense of the communal energy that fuels social atmosphere, so even packed-out immersive shows can seem like solitary pursuits, with human companions resembling NPCs (non-playable videogame characters).

The cultural academic Keren Zaiontzcoineda sharp term for our consumption of immersive entertainment: “narcissistic spectatorship”. Onestudyfound VR use induced dissociative symptoms in 83.9 per cent of participants. The long-term effects remain nebulous, but research, including astudyof VR tourist experiences, has highlighted recurring themes of addiction to the experience and isolation.

Over at London’s Barbican Centre,Feel the Soundis a new immersive exhibition whose installations offer imaginative personalised features, includingYour Inner Symphony‘s “sensing stations”, which generate unique visuals by tracking our bodily reactions to music. Luke Kemp, who heads up the Barbican’s immersive programming, says these experiences respond to our need for “playful” cultural spaces, accessible regardless of prior knowledge: “It allows the audience to have agency, and to feel part of something.”

Robyn Landau at Kinda Studios, co-developer ofYour Inner Symphony, points out the link to interoception – our awareness of our body’s inner senses. “When we have these transformative experiences individually that connect us to ourselves, they actually transform how we show up in the world and the way we connect to others,” she says.

According to psychologist Sophie Janicke-Bowles, immersive experiences create scenarios where our “processing power is challenged just enough to keep us interested”. This “can have an incredible recovery effect on our psyche, where we can detach from our everyday concerns and cognitively, emotionally and even physiologically get absorbed into something different”, she tells me.

Having grown up clubbing, I am struck by how many immersive experiences evoke the dancefloor; the extraordinaryIn Pursuit Of Repetitive Beats, a multi-player VR homage to the UK rave scene in which networked headsets allow groups to interact in real time, is also at the Barbican.

But for me, there is still a curious tension at play in immersive entertainment, and I am torn about where the rapidly developing scene is taking us. It does give us an opportunity to tune into ourselves, but I am less convinced it amplifies our bond with those around us. If we remain fixated by our own reflections, then we are missing the bigger picture. Immersive entertainment might make VIPs of us all, but culture should also bring us together.

Arwa Haider is a culture journalist based in London

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The herpes virus that commonly causes cold sores affects how tightly coiled our DNA is and makes it shrink, all to help itself grow

Human DNA in its natural state inside cells (left) compared with its state 8 hours after being infected with the cold sore virus (right)Esther Gonzalez Almela and Álvaro Castells García

Human DNA in its natural state inside cells (left) compared with its state 8 hours after being infected with the cold sore virus (right)

Esther Gonzalez Almela and Álvaro Castells García

The virus that commonly causes cold sores starts reshaping our genome within an hour of infection to boost its own growth, which scientists could take advantage of to treat severe cases.

Billions of people around the world have the infection, caused by herpes simplex virus type 1 (HSV-1), although many of them don’t know it. It can spread through contact with other cold sores, saliva or even unbroken skin around the mouth.

Read moreHow to tell if your immune system is weak or strong

How to tell if your immune system is weak or strong

After invading host cells, the virus replicates in the nucleus, where genetic material is stored as strands ofDNA. These strands wrap around proteins, with some regions forming tight coils, inactivating the genes within them, while others form wider loops, where genes are active. In these looser regions, proteins can unwind and transcribe DNA into the molecule RNA, which encodes for proteins that keep the cell running.

Prior studies had shown that the human genomebecomes more tightly coiledduring HSV-1 infection, whichmay disrupt cell function, but it was unclear why this coiling occurs.

To learn more,Alvaro Castells-Garciaat the Centre for Genomic Regulation in Barcelona, Spain, and his team imaged HSV-1 while it infected human lung cells, using a microscope that can capture structures 3500 times thinner than a strand of hair. “It’s a higher resolution than most prior studies,” says Castells-Garcia.

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They found that within 1 hour of the virus enteringcells, it had stolen transcription proteins away from the human genome, something prior studies had already suggested.

But they also showed that this theft is what seems to cause the host DNA to coil up more tightly, making it shrink to 30 per cent of its pre-infection volume within 8 hours of infection.

The virus also made contact with specific regions of the host genome that encode for the transcription proteins it steals, preventing those regions from coiling up and boosting the activity of genes within them that help it grow.

“We used to think it made contact with our genome randomly,” says team memberEsther González-Almela, also at the Centre for Genomic Regulation. “But the virus is able to contact our own genome in specific regions, and these regions usually harbour genes that are involved in the continuity of infection, in making viral RNA and proteins.”

The truth about the foods said to boost your immune systemMany foods thought to enhance our natural defences, such as orange juice and turmeric, don’t live up to the hype. Instead, the key to a healthy immune system lies in nurturing your gut microbiome

The truth about the foods said to boost your immune system

Many foods thought to enhance our natural defences, such as orange juice and turmeric, don’t live up to the hype. Instead, the key to a healthy immune system lies in nurturing your gut microbiome

In another part of the study, the researchers found that using an experimental cancer drug to block one of the transcription proteins that HSV-1 steals prevented it from replicating in human lung cells in the lab. This suggests that the drug could help treat HSV-1 in people with severe cold sores or those who have a suppressed immune system and are more likely to experience complications, says González-Almela. Milder cases are usually left to clear up on their own.

It could even work against otherviruses, such as adenoviruses, which cause colds, and varicella zoster virus, which causes chickenpox. “Other viruses similar to HSV-1 may use similar strategies,” saysBenjamin Krishnaat the University of Cambridge. “There’s a possibility that these [sorts of experimental drugs] could treat those as well,” he says.

Journal reference:Nature CommunicationsDOI: 10.1038/s41467-025-60534-6

Nature CommunicationsDOI: 10.1038/s41467-025-60534-6

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A skull from China has been identified as Denisovan using molecular evidence – so ancient humans once known solely from their DNA finally have a face

Hominin cranium from Harbin, China, now identified as a DenisovanHebei GEO University

Hominin cranium from Harbin, China, now identified as a Denisovan

TheDenisovans, a mysterious group of ancient humans originally identified purely from DNA, finally have a face.

Using molecular evidence,Qiaomei Fuat the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing and her colleagues have confirmed what many researchers suspected: that a skull from China known as “dragon man” belonged to a Denisovan.

Read moreThe other humans: The emerging story of the mysterious Denisovans

The other humans: The emerging story of the mysterious Denisovans

This fits with other evidence suggesting that the Denisovans were large and stocky. “I think we’re looking at individuals that are all [around] 100 kilos [of] lean body mass: enormous, enormous individuals,” saysBence Violaat the University of Toronto in Canada, who was not involved in the study.

The Denisovans were first identified in 2010. In Denisova cave in the Altai mountains of Siberia, researchers found a sliver of finger bone from an unidentified ancient human. Preserved DNA revealed that it wasn’t a modern human (Homo sapiens), nor a Neanderthal (Homo neanderthalensis), butsomething hitherto unknown.

Genetic evidence also revealed thatDenisovans had interbred with modern humans. Today, populations in South-East Asia and Melanesia carry up to 5 per centDenisovan DNA,which implies that Denisovans were once widespread in Asia.

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After these discoveries, researchers began looking for Denisovan fossils, both in the field and in museum collections.Several have been found, notablya lower jawbonefrom Baishiya Karst cave on the Tibetan plateau, which was confirmed using proteins from the fossil andDNA from surrounding sediments. In April,a jawbone dredged from the Penghu Channeloff the coast of Taiwan was confirmed to be Denisovan, based on preserved proteins.

However, there was still a frustrating disconnect. The fossils confirmed as Denisovans using molecular evidence were all small, so they weren’t very informative. Meanwhile, there were manymore complete fossilsfrom Asia that weresuspected to be Denisovan, butnone had yielded molecular evidence.

Fu and her colleagues set out to obtain preserved DNA or protein from a hominin cranium found in Harbin in north-east China. First described in 2021 after having been kept secret for decades, the cranium is unusually large and bulky, with thick brow ridges and capacity for a brain of a similar size to ours.It was namedHomo longi– or dragon man – by its discoverers.

“My impression was, this is the right kind of thing in the right place at the right time to be a Denisovan,” says Viola.

Fu says it was extremely difficult to get preserved molecules from the Harbin cranium. Her team’s attempts to obtain DNA from the bone proved fruitless. However, they did manage to get 95 proteins, which included three variants that are unique to Denisovans.

Feeling that this wasn’t enough to be certain, Fu began testing dental calculus, the hard plaque that forms on teeth. This yielded mitochondrial DNA, which is inherited from the mother. It was a “tiny amount”, she says, but enough to confirm that the remains were Denisovan.

“That’s an incredible result, and fantastic that they even tried,” saysSamantha Brownat the National Research Center for Human Evolution in Burgos, Spain. “I think most researchers would overlook dental calculus for genetic studies.”

Read moreSurvival of the friendliest? Why Homo sapiens outlived other humans

Survival of the friendliest? Why Homo sapiens outlived other humans

Now that the bulky Harbin skull has been identified as Denisovan, it confirms something long suspected: Denisovans were big.

“There were clues [to] that right from the beginning with their teeth,” says Brown: the handful of molars that were found were unusually large. Known jawbones were also big. “We thought Neanderthals were the stocky ancestor, but actually it might be Denisovans that really were the big boys of the palaeontological record.”

It isn’t clear why this was the case. Neanderthals’ size and build have been linked to the cold climates in Europe and western Asia where they lived. Some Denisovan sites, including Denisova cave and the Tibetan plateau, were also cold – but others were tropical. “I think we’ll have to think about what this really means,” says Viola.

It may be that the Denisovans changed over time. Fragments from Denisova cave reveal two groups: one from 217,000 to 106,000 years ago, and the other from 84,000 to 52,000 years ago. The Harbin cranium is at least 146,000 years old, and Fu found that its proteins and mitochondrial DNA matched the older group. But we don’t have confirmed large fossils of the more recent Denisovans, so we don’t know what they were like.

“There’s just lots of different groups of these guys who are moving around the landscape, kind of independently, that are often separated from each other for probably tens of thousands of years,” says Viola. We shouldn’t expect them to all look alike, he says.

Journal reference:CellDOI: 10.1016/j.cell.2025.05.040

CellDOI: 10.1016/j.cell.2025.05.040

Journal reference:ScienceDOI: 10.1126/science.adu9677

ScienceDOI: 10.1126/science.adu9677

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Rocks in some parts of the UK have the potential to produce natural hydrogen, but it remains unclear whether the gas is present in economically viable quantities

The Lizard peninsula in Cornwall contains rocks that could generate hydrogen gaspio3/Shutterstock

The Lizard peninsula in Cornwall contains rocks that could generate hydrogen gas

In recent years, the discoveryof small amounts of hydrogen gas undergroundhas spurred a worldwide search for what could prove to be a significant new source of zero-carbon fuel, but so far, prospectors have largely skipped the UK.

According to abriefingon natural hydrogen produced by the Royal Society, that isn’t due to its geology. “There are rocks that certainly would fit within having the potential to produce hydrogen, but the investigations haven’t been done,” saysBarbara Sherwood Lollarat the University of Toronto in Canada, who led work on the report.

Read moreThe gold hydrogen rush: Does Earth contain near-limitless clean fuel?

The gold hydrogen rush: Does Earth contain near-limitless clean fuel?

It also isn’t down to lack of interest in the gas. The UK’s latesthydrogen strategysays that when produced via low-carbon methods, it “has a critical role in helping to achieve our Clean Energy Superpower Mission”, including as a source of power for heavy industry and transportation and in long-duration energy storage. Natural hydrogen, however, isn’t mentioned as a potential source.

Novelty is one reason for this, saysPhilip Ballat Keele University, UK, who contributed to the report and is an investor in natural hydrogen companies. “Nobody is paying attention, basically. No one is regulating this new subject. No one understands it.”

That could be starting to change. Ball says several companies have purchased rights to explore for hydrogen in parts of the UK, for instance inDevonin the south-west, while relevant research is going on at several universities. The British Geological Survey is also working on a more detailed study of the potential for natural hydrogen in the UK. The country’s rich history of geological study means there is plenty of data to draw on.

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And there is reason to think there might be something to find in it. According to the Royal Society report, the UK has ample amounts of the rocks known to generate natural hydrogen, for example iron-rich ultramafic rocks that produce the gas when they react with water. These occur in regions such as the Lizard peninsula in Cornwall and the Shetland Islands in Scotland. Geological formations in other areas such as the North Pennines may also produce hydrogen as a result of natural radioactivity splitting water molecules.

“It’s most definitely going to be in the UK,” says Ball. “Whether it’s in economic quantities is the question.”

Read moreInside the Brooklyn start-up making clean jet fuel with captured CO2

Inside the Brooklyn start-up making clean jet fuel with captured CO2

If there is hydrogen to be found beneath the UK, no one should expect “some bonanza of an endlessly renewable commodity”, says Sherwood Lollar. She says one broader purpose of the report was to offer a “course correction” for some of themore dubious claimsthat have been made about natural hydrogen, such as the idea that large amounts of the gas are rising from deep in Earth’s mantle or even core.

That said, moreconservative estimatesof how much hydrogen may be generated in the crust are still significant: the report estimates that around 1 million tonnes of the gas seep out of the crust each year globally, which over time could produce somelarge accumulations. “Even if we can capture a small proportion of this, it could still be an important contributor to the hydrogen economy,” says Sherwood Lollar.

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From spiders to scorpions, some 1000 different invertebrate species are traded globally as pets. This is bad for biodiversity – but there is an upside, saysGraham Lawton

A Mexican redknee tarantula (Brachypelma smithi)Shutterstock/Milan Zygmunt

A Mexican redknee tarantula (Brachypelma smithi)

When I was about 7 or 8 years old, my biology-professor dad brought me a present home from work: a jar of sticks. Or at least that’s what I thought it was. When some of them started moving he explained that they were stick insects. I kept them for a while and found them fascinating. They weren’t cute and cuddly but they had something else: they were cool.

Seems I was ahead of my time. Last month, two Belgian teenagers were released from jail in Kenya after paying a fine for wildlife piracy. Their crime, to which they pleaded guilty, was attempting to smuggle 5000 ants out of the country. Smuggled ants often turn up in what reports describe as a “booming” global trade inexotic invertebrate pets. Their haul included giant African harvester ants (Messor cephalotes). A colony of these highly prized mini-beasts sells for around £170 in the UK.

Ants are by no means the only invertebrate group being traded and kept as pets. The menagerie also includes spiders, scorpions, mantises, beetles, cockroaches, grasshoppers, snails, slugs and, of course, stick insects.

A recent reviewfoundthatalmost 1000 invertebrate speciesare being traded on the exotic pet market. Some are traded legally, but others are contraband. Giant African harvester ants, for example, are a protected species in Kenya.

Keeping invertebrates as pets may seem like a harmless hobby, but it can have serious consequences for biodiversity. Putting firm numbers on any of this is difficult, but an estimated two-thirds of the arachnids on the market are poached from the wild. In Mexico, overharvesting ofBrachypelmatarantulas has causedsignificant population declines. In the limestone karsts under the Dinaric Alps of south-eastern Europe,poachers of troglobionts– animals adapted to living in caves – have helped to push several already-endangered insects closer to extinction.

Unsustainable harvesting also damages the wider ecosystem. Invertebrates are an important food source for many vertebrates, and they supply vital ecosystem services such as decomposition and nutrient cycling.

Poaching destroys habitats directly. Many prized tarantulas live in vase-shaped plants called bromeliads, which also provide a home to frogs and other animals. According toCaroline Sayuri Fukushimaat Tarantupedia, an online taxonomic database of large spiders, the poachers just chop the plants down, killing them and their captive ecosystems. In the Balkans, the poachers set pitfall traps that kill thousands of non-target species.

In Mexico, the overharvesting of tarantulas has caused significant population declines

In Mexico, the overharvesting of tarantulas has caused significant population declines

Exotic invertebrates are also a threat to the locations where they end up. Indeed, 57 ant species known to be traded are classed as invasive by the International Union for Conservation of Nature (IUCN), and 13 of them are among the top 20 worst global ant invaders.

Stopping the trade will be very difficult. The Kenyan judges – who sentenced the Belgians to either a fine of 1 million Kenyan shillings (£5700) or a year in jail – reportedly said they wanted to send a strong message that trafficking of all protected wildlife is unacceptable. But people must be getting away with it. I found several websites advertising giant African harvester ants, which live only in East Africa.

The Belgian teenagers were caught red-ant-handed, but according to the authors of a2022 surveyof the global arachnid trade, smuggling invertebrates is relatively straightforward, at least compared with smuggling vertebrates. They are small and easily concealed, and aren’t picked up by X-ray machines or thermal cameras at airports. Protected species can also be laundered as legally tradeable ones, as customs officers lack the taxonomic expertise to tell them apart.

It’s the same old story of greed, exploitation and destruction. But it doesn’t have to be like this. According to biologists who study it, the trade in invertebrates can be a force for good. Sustainable harvesting of wild species can support the livelihoods of some of the world’s poorest people, while also diverting them away from more harmful acts such as illegal logging. Increased recognition of the trade is stimulating much-needed research on wild populations of target species and their conservation status. It is also getting organisations such as the IUCN to pay attention to a group of animals they have historically neglected.

As for the collectors themselves, they are obviously interested in the amazing variety of life on this planet, and could also be recruited into the fight to save it. I think they should be allowed to indulge their hobby, albeit within a well-regulated system of sustainably harvested or captive-bred, non-invasive invertebrates. I won’t be getting any more stick insects, but they certainly helped to stimulate my interest in the natural world.

Many Things Under a Rock: The mysteries of octopusesby David Scheel.

The York Festival of Ideas is on this week, so I’ve been going to talks and events looking for… er… ideas.

Graham Lawton is a staff writer at New Scientist and author of Mustn’t Grumble: The surprising science of everyday ailments. You can follow him @grahamlawton

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Trees would have to be planted on a vast proportion of global land mass to offset the carbon dioxide emissions from burning the world’s fossil fuel reserves

A tree-planting project in British Columbia, CanadaJames MacDonald/Bloomberg via Getty Images

A tree-planting project in British Columbia, Canada

James MacDonald/Bloomberg via Getty Images

It would be nearly impossible to plant enough trees to compensate for the climate impact of burning through the world’s fossil fuel reserves. Offsetting the estimated 182 billion tonnes of carbon held in the reserves of the world’s largest fossil fuel companies would require covering more land with trees than the entirety of North and Central America.

The analysis, byAlain Naefat ESSEC Business School in France and his colleagues, assessed the cost and viability of offsetting the carbon emissions from burning the oil, gas and coal reserves held by the largest 200 fossil fuel firms around the world.

Read moreOur plans to tackle climate change with carbon storage don't add up

Our plans to tackle climate change with carbon storage don't add up

The researchers found that an area greater than 24.75 million square kilometres would have to be planted with new trees to offset the impact of burning these reserves, swallowing the equivalent of the entire landmass of North America, Central America and parts of South America combined.

This would be impractical to achieve in reality, requiring the displacement of settlements, farmland and other existing natural habitats.

“There simply isn’t enough land available for the level of afforestation that would be needed to offset fossil fuel-related emissions,” saysRich Collett-Whiteat UK energy analysts Carbon Tracker. “Pursuing anywhere near that level of afforestation risks increasing food prices – if farmland is diverted to afforestation – or indirectly causing deforestation elsewhere to meet global food demand.”

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Meanwhile, the financial cost of such a mass-scale afforestation scheme would be ruinous. The cost of tree planting is around $16 per tonne of CO₂ equivalent that is offset. At this price, using trees to offset emissions from fossil fuel reserves would eliminate the entire market value of 64 per cent of the largest fossil fuel companies, the team found. This doesn’t include the cost of acquiring the land.

If a higher carbon price is used, in order to account for the negative social and economic consequences of fossil fuel combustion, the findings suggest all of the companies would essentially become bankrupt.

Read moreThe ocean is losing its ability to store heat as the planet warms up

The ocean is losing its ability to store heat as the planet warms up

Naef and his colleagues acknowledge there is little chance of fossil fuel companies voluntarily offsetting the emissions of their reserves. Instead, they say the work is a thought experiment to underscore that offsetting cannot be used to allow polluting industries to continue business-as-usual operations. “Our key message from this paper is that this oil and gas should remain in the ground,” Naef told a press briefing on 18 June.

Tim Raydenat Trillion Trees, a UK tree-planting campaign group, agrees. “Planting trees is not a substitute for rapid phase-out of fossil fuels and must not replace action to decarbonise our economies,” he says.

Journal reference:Communications Earth & EnvironmentDOI: 10.1038/s43247-025-02394-y

Communications Earth & EnvironmentDOI: 10.1038/s43247-025-02394-y

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Treating types of cancer with CAR T-cell therapy is expensive and inconvenient, but a streamlined approach that creates the therapy within the body could make the intervention cheaper and easier

Illustration of CAR T-cell therapy targeting multiple myeloma, a type of blood cancerNemes Laszlo/Alamy

Illustration of CAR T-cell therapy targeting multiple myeloma, a type of blood cancer

CAR T-cell therapy has the potential to revolutionise how we treat certain types ofcancerby genetically engineering someone’s own immune cells to attack the disease – but it is also cumbersome and expensive. Now, scientists have managed to create the bespoke therapy inside the body of non-human animals, which could simplify the process, driving costs down.

The treatment is mainly available in countries including the UK and US for some people with various types of blood cancer, including some types of leukaemia, where B-cells, a part of theimmune system, grow uncontrollably. In these cases it involves collecting a sample of immune cells called T-cells from the blood of a patient and genetically engineering the genome within those cells to permanently target and kill B-cells. These engineered T-cells are then multiplied and infused back into the body.

Read moreWe are finally improving prostate cancer diagnoses – here's how

We are finally improving prostate cancer diagnoses – here's how

But this process takes time. “You’ve got to take blood, ship it to a central manufacturing lab and then return [the T-cells],” saysCarl Juneat the University of Pennsylvania. “That means it’s very hard to scale up.” It can also costupwards of $500,000per patient.

To develop a more efficient approach, June and his colleagues turned to genetic molecules, in this caseRNA, that carried instructions to make a protein that recognises B-cells. They packaged these molecules into fatty capsules, which were coated in a protein that allows them to get into T-cells, which then gain the ability to recognise and destroy B-cells. This effect is only temporary, however, as the RNA code remains in the T-cells for about a week before degrading.

Putting their approach to the test, the researchers infused cancerous human B-cells and healthy human T-cellsinto mice that had been bred to lack an immune system. One week later, they injected the animals with five doses of the fatty capsules across roughly two weeks, with some mice receiving higher doses than others.

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Three weeks later, the mice that received the highest dose had no detectable tumour cells and experienced no side effects. “Tumour cell levels were as close as we can detect to being eliminated,” says June.

The team also injected the fatty capsules into 22 healthy monkeys. This generated CAR T-cells in the body that completely cleared all B-cells within just one day, which suggests that the approach could also treat this type of leukaemia in primates. B-cells, which make antibodies, are an important part of the immune system, yet the treatment was well tolerated in all but one of the monkeys, which had a severe inflammatory reaction.

mRNA cancer therapy now in human trials after shrinking mouse tumoursAn mRNA cancer treatment developed by BioNTech and Sanofi is being tested in people after shrinking tumours in mice, and is hoped to repeat the success of mRNA covid-19 vaccines

mRNA cancer therapy now in human trials after shrinking mouse tumours

An mRNA cancer treatment developed by BioNTech and Sanofi is being tested in people after shrinking tumours in mice, and is hoped to repeat the success of mRNA covid-19 vaccines

“This is really impressive,” saysKarin Straathofat University College London. It is a potentially much simpler procedure for making CAR T-cell therapy, which could make it more affordable, she says.

But one benefit of traditional CAR T-cells is that they can offer long-term protection, says Straathof. The new approach only temporarily produces such cells, so further injections would be needed if the cancer returns. We also can’t be sure of the latest method’s effectiveness or safety in people without clinical trials, she says.

June says the team is already testing the approach in healthy humans. “The first person was dosed in the past few weeks,” he says.

Journal reference:ScienceDOI: 10.1126/science.ads8473

ScienceDOI: 10.1126/science.ads8473

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A newly identified brain circuit in mice may explain why we sleep longer and deeper after being sleep deprived – and lead to new treatments for sleep conditions

How does the brain encourage us to make up for sleep loss?Connect Images/Getty Images

How does the brain encourage us to make up for sleep loss?

Researchers have discovered neurons in mice that help their brains track and recover fromsleep debt. If a similar pathway exists in humans, it could improve treatments for sleep disorders and other conditions marked by sleep impairment, such asAlzheimer’s disease.

We are all familiar with sleep debt, or the gap betweenhow much sleep you needand how much you actually get. But until now, it wasn’t clear how the brain tracks sleep loss – or compels us to make up this difference.

Read moreBeyond tired: Why fatigue sets in and how to tackle it

Beyond tired: Why fatigue sets in and how to tackle it

Mark Wuat Johns Hopkins University in Maryland and his colleagues mapped brain pathways in mice that are involved in sleep by injecting a tracer into 11 brain areas known to induce sleep. The tracer, which travels from neurons receiving signals to those sending them, revealed 22 regions with connections to at least four sleep-promoting areas.

The researchers focused on a subset of 11 previously unidentified regions. Using a technique called chemogenetics, they gave mice specialised drugs that activate particular parts of their brains. They divided the mice into 11 groups of three to four individuals, activating a different area in each group.

A region called the thalamic nucleus reuniens seemed to be key. When neurons in this area were stimulated, the mice experienced the greatest increase in non-rapid eye movement (REM) sleep – about twice the amount as mice that weren’t stimulated. However, it took several hours for the animals to fall asleep after stimulation, during which they seemed to prepare for rest.

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“When you go to bed, you probably brush your teeth, you wash your face, you fluff your pillow or arrange your blanket and then go to sleep,” says Wu. Mice do something similar. “They kind of groom their face, they clean their whiskers and then they fluff their nest up,” he says. This suggests these neurons aren’t an on-and-off switch for sleep – instead, they induce sleepiness.

Another test also supported this idea. In six sleep-deprived mice, deactivating the thalamic nucleus reuniens brain cells made the rodents lesssleepy– they were more active and spent less time nesting than control mice. They also got 10 per cent less non-REM sleep, on average.

Other experiments showed that these neurons activate during sleep deprivation and quiet down once sleep begins.

Together, the findings suggest this brain region drives sleepiness and triggers restorative sleep after sleep loss, says Wu. Developing therapies that target these neurons could lead to new treatments for hypersomnia – a sleep disorder characterised by excessive sleepiness after rest – as well as conditions such as Alzheimer’s disease, in which people don’t sleep enough.

However, it isn’t clear if the same brain circuit exists in humans, saysWilliam Giardinoat Stanford University in California. We also don’t know whether it plays a role in long-term sleep deprivation. “They’re focusing more on the short-term effects of sleep deprivation, which might not closely model humans with years and years and years of sleepless nights,” he says.

Journal referenceScienceDOI: 10.1126/science.adm8203

ScienceDOI: 10.1126/science.adm8203

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Unlike other primates, humans are exposed to high levels of placental sex hormones in the womb, which may have shaped our evolutionary brain development

Exposure to hormones in utero could affect human brain growthPeter Dazeley/Getty Images

Exposure to hormones in utero could affect human brain growth

The human brain is one of the most complex objects in the universe – and that complexity may be due to a surge of hormones released by theplacentaduring pregnancy.

While numerous ideas have been proposed to explain human brain evolution, it remains one of our greatest scientific mysteries. One explanation, known as thesocial brain hypothesis, suggests that our large brains evolved to manage complex social relationships. It posits that navigating large group dynamics requires a certain degree of cognitive ability, pushing social species to develop bigger brains. For instance, other highly sociable animals, such as dolphins and elephants, have relatively large brains too. But the biological mechanism underlying this link has remained unclear.

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Now,Alex Tsompanidisat the University of Cambridge and his colleagues say the answer may be placental sex hormones. During pregnancy, the placenta – a temporary organ that acts as an intermediary between the fetus and the mother – produces hormones crucial for fetal development. These include sex hormones such as oestrogens and androgens.

“I know that seems like a jump – thinking about human evolution and then ending up on the placenta,” says Tsompanidis. “But the reason for that is because we’ve been looking at the fluctuations and variations in the levels of these hormones in the womb and seeing that they predict things like language development and social development.”

Emerging research also shows that these hormones influence the developing brain. For instance, a2022 studyfound that administering androgens, such as testosterone, tobrain organoids– simplified, miniature versions of the brain made from human stem cells – during a critical developmental period increased the number of cells in the cortex, a brain region crucial for memory, learning and thinking. Other studies in brain organoids have shown that oestrogens are important for forming and stabilising connections between neurons.

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There is also some limited evidence that humans are exposed to higher levels of these hormones during pregnancy than non-human primates are. A1983 studyfound that gorillas and chimpanzees have four to five times less oestrogen in their urine than humans during pregnancy. The placenta also hasmore activity in genesthat produce aromatase – an enzyme that converts androgens into oestrogens – in humans than in macaque monkeys.

“These hormones have become very important for brain development, and if we look at it comparatively with other primates and other species, there seems to be evidence that these hormones are very high in humans [during pregnancy],” says Tsompanidis.

This influx could also help explain why humans form such large social groups. Some evolutionary biologists believe that we are able to build extensive social networks because the differences between the sexes are more subtle in humans than in other primates. For example, men and women are more similar in body size than male and female Neanderthals, says Tsompanidis. This is probably due to higher oestrogen levels in utero, he says.

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“If you have a lot of oestrogen, not only are you a bit less masculinised, but you’re also more likely to have an interconnected brain,” says Tsompanidis. “So the push to increase oestrogen, the push to make everyone social and getting along, is actually what makes the human brain larger and more connected.”

“I agree that placental genes influence human brain development and likely hominin brain evolution,” saysDavid Gearyat the University of Missouri. “However, I think they are underestimating the influence of male-male competition on brain and cognitive evolution.”

While it is true that male humans within the same social group tend to be more cooperative and less aggressive towards one another than is seen in other primates, this may have evolved as a result of between-group conflicts, he says. After all, greater coordination and teamwork would be an advantage in a deadly confrontation, he points out.

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Our knowledge of placental differences between primates is also limited. Many non-human primates, such as chimpanzees, eat the placenta after giving birth, making it difficult to study, says Tsompanidis.

Identifying which factors shaped human brain evolution is more than just an intellectual pursuit: it could also shed light onneurodiversity.

“Not all humans are social or have incredible language skills – and that is fine. That doesn’t make them any less human,” says Tsompanidis. Understanding how the brain evolved could provide insight on whether certain cognitive traits come with trade-offs, he says.

Journal referenceEvolutionary AnthropologyDOI: 10.1002/evan.70003

Evolutionary AnthropologyDOI: 10.1002/evan.70003

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Agatha Christie's murder mysteries are made all the more compelling by the author's personal expertise, reveals Kathryn Harkup's new book V is for Venom

A talent for murder: Agatha Christie is one of the world’s bestselling writersShutterstock/Doodeez

A talent for murder: Agatha Christie is one of the world’s bestselling writers

V Is for VenomKathryn Harkup (Bloomsbury Sigma)

Agatha Christie’s  five-decade writing career saw her poison dozens of her characters, supplying the killers in her stories with an assortment of deadly chemicals, including poisons and venoms produced by living organisms and delivered via injection.

Chemist Kathryn Harkup has visited their use before in 2015’sA Is for Arsenic.V Is for Venom:Agatha Christie’s chemicals of deathlooks at “the more unusual means of chemical killing that [make] Agatha Christie a true ‘Queen of Crime’.”

Christie’s murderswere made all the more authentic due to her scientific background: she was a pharmaceutical dispenser before she became a bestselling writer, and she furthered her knowledge of toxicology while volunteering as a nurse during the first world war. Harkup presents a detailed but never overwhelming account of the substances at the centre of her stories – and how many of them didn’t come in small bottles conveniently marked “Danger”.

Spoiler: a dirty bandage that had recently dressed a cat’s ear infection is used to spread septicaemia in 1939’sMurder Is Easy,while the killer inSparkling Cyanideharnesses carbon monoxide from coal gas. Harkup explains the science behind each murder, avoiding spoilers where possible. She considers, for example, the feasibility of a “poisoned dart hidden in an adapted cigarette” and the consequences of imbibing toxic hat paint (feasible and not good, respectively).

Harkup’s analysis stretches to the fictional poisons Christie invented, like Benvo from 1970’sPassenger to Frankfurt, a drug that causes its victim to become fatally benevolent (Harkup concludes that “apparently, this is a bad thing”).

Antidotes to the murder methods are outlined – CPR may have saved the life of the dinner party guest who had unknowingly ingested opioids in 1962’sThe Mirror Crack’d from Side to Side, while real-life cases that likely inspired Christie’s plots are explained in asides.

Drugged drinks are used as a murder method in several of Christie’s novels. Harkup writes of the disgraced Scottish chemist who worked as a bartender in 1870s San Francisco, and whose chloral hydrate “knockout drops”, slipped into patrons’ beer glasses, would later take his name: Mickey Finn.

Harkup reveals that many of the drugs from Christie’s stories are still widely available. Barbiturates, as featured in 1933’sLord Edgware Dies, are today prescribed as epilepsy treatments, such as Seconal. But she cautions against using Christie’s chemicals as “homicidal inspiration”, explaining that toxicology was “a little different at the time Christie was writing”. Would-be poisoners attempting to mimic her assassinations today would either be swiftly detected or else suffer a calamity.

Harkup balances the macabre with the scientifically intricate. For every passage detailing the chemical history of chloroform, there are accounts of real murders that Christie’s imagination may have influenced. We learn of a poisoned billionaire who in 2011 died after eating cat-meat stew laced with gelsemium, the same plant featured in 1927’sThe Big Four. Harkup also deconstructs the hydrochloric acid murder in 1936’sMurder in Mesopotamia, drawing comparisons with today’s corrosive substance attacks.

Christie’s inventive killings made her a perennial bestseller. But it’s fitting that, as Harkup highlights, one of her favourite accolades came viaThe Pharmaceutical Journal. In response to her debut novel, 1920’sThe Mysterious Affair at Styles, the scientific review noted, “This novel has the rare merit of being correctly written.”

George Bass is a writer based in Kent, UK

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