Ethics debate as pig brains kept alive without a body

Researchers at Yale University have restored circulation to the brains of decapitated pigs, and kept the organs alive for several hours.

Their aim is to develop a way of studying intact human brains in the lab for medical research.

Although there is no evidence that the animals were aware, there is concern that some degree of consciousness might have remained.

Details of the study were presented at a brain science ethics meeting held at the National Institutes of Health (NIH) in Bethesda in Maryland on 28 March.

The research has also been reported on this week in the MIT Technology Review.

The work, by Prof Nenad Sestan of Yale University, was discussed as part of an NIH investigation of ethical issues arising from neuroscience research in the US.

Prof Sestan explained that he and his team experimented on more than 100 pig brains.

They discovered that he could restore their circulation using a system of pumps, heaters, and bags of artificial blood.

As a result the researchers were reportedly able to keep the cells in the brain alive and capable of normal activity for as long as 36 hours.

Prof Sestan is said to have described the result as “mind-boggling”. If this could be repeated with human brains, researchers would be able to use them to test out new treatments for neurological disorders.

But Prof Sestan is among the first to raise potential ethical concerns. These include whether such brains have any consciousness and if so deserve special protection, or whether their technique could or should be used by individuals to extend their lifespans – by transplanting their brains when their bodies wear out.

In a commentary published in the Journal Nature this week, Prof Sestan and 15 other leading US neuroscientists called for clear regulation to guide them in their work.

“If researchers could create brain tissue in the laboratory that might appear to have conscious experiences or subjective phenomenal states, would that tissue deserve any of the protections routinely given to human or animal research subjects?”, the researchers ask in the commentary.

“This question might seem outlandish. Certainly, today’s experimental models are far from having such capabilities. But various models are now being developed to better understand the human brain, including miniaturised, simplified versions of brain tissue grown in a dish from stem cells. And advances keep being made.”

The researchers say that ways of measuring consciousness need to be developed and strict limits set for them to be able to continue their work with the public’s support.

  • Brain back-up venture ‘will kill users’
  • Rules of memory ‘beautifully’ rewritten
  • Would you preserve your brain for future generations?

    Prof Colin Blakemore, of the School of Advance Study at the University of London, backs the research team’s call for a public debate on the issue.

    “The techniques, even to a researcher, sound pretty ghoulish – so it is very, very important that there should be a public discussion about this, and not least because the researchers who have some investment can tell the public why it would be so important to develop such techniques,” he told BBC News.

    “There is a paradox here, and that is – the better such methods are at maintaining a whole brain, fully functional but without connection to a body, the more useful that would be for research purposes. But the more likely it would also be for the brain to have some sentience and consciousness, which would be deeply worrying”.

    Prof Blakemore said that he was “very uneasy about the quest for immortality” by those considering preserving their brains until surgery advances, in order to place them in a new body.

    “Our planet is already overpopulated. You need space for young people and new ideas, and the notion of desperately clinging on to any mechanism possible for human beings living forever, I find very unsavoury.”

Sentinel tracks ships’ dirty emissions from orbit

The new EU satellite tasked with tracking dirty air has demonstrated how it will become a powerful tool to monitor emissions from shipping.

Sentinel-5P was launched in October last year and this week completed its in-orbit commissioning phase.

But already it is clear the satellite’s data will be transformative.

This latest image reveals the trail of nitrogen dioxide left in the air as ships move in and out of the Mediterranean Sea.

The “highway” that the vessels use to navigate the Strait of Gibraltar is easily discerned by S5P’s Tropomi instrument.

“You really see a straight line because all these ships follow approximately the same route,” explained Pepijn Veefkind, Tropomi’s principal investigator from the Dutch met office (KNMI).

“In this case, we also looked into how many big ships there are in the region [at the time], and there’s really not that many – around 20 or so, we estimate – but each one is putting out a lot of NO₂.”

  • Shipping in ‘historic’ climate deal
  • Oceans Sentinel goes into orbit
  • New Sentinel satellite tracks dirty air

    Nitrogen dioxide is a product of the combustion of fuels, in this instance from the burning of marine diesel. But it is also possible to see in the picture the emissions hanging over major urban areas on land that come from cars, trucks and a number of industrial activities. NO₂ will be a major contributor to the poorer air quality people living in those areas experience.

    Sentinel-5P is the next big step because of its greater sensitivity and sharper view of the atmosphere.

    “Shipping lanes are something we’ve seen on previous missions but only after we’ve averaged a lot of data; so, over a month or a year. But with Tropomi we see these shipping lanes with a single image,” Dr Veefkind told BBC News.

    “The resolution we got from our previous instruments was about 20km by 20km. Now, we’ve gone down to 7km by 3.5km, and we are thinking of going to even smaller pixels.”

    Eyes in the sky

    Analysis by David Shukman, BBC Science Editor

    Far beyond the horizon, steaming through the remote High Seas, the great fleets of global shipping have for years been too distant to be observed.

    Only in port can anyone catch sight of the plumes of dark smoke rising from the vessels’ engines. But added together, the greenhouse gases from the world’s 50,000 ships make this industry the world’s sixth largest emitter, and most of it is unseen. This has long fuelled suspicions among environmental campaigners.

    Exempt from the Kyoto Protocol and then the Paris Agreement, shipping acquired a reputation as a sector that dodged its responsibilities on climate change. That’s why the landmark deal earlier this month for a cut in emissions of 50% by 2050 received so much attention. But it also raised a host of questions about policing: who would keep watch, and how?

    Europe’s Sentinel programme is part of the answer. Suddenly, at just the right time, the world’s shipping lanes are in full view.

    S5P’s availability is timely. The shipping sector has just signalled its intention to make big reductions in its emissions over the next 30 years, in particular of the greenhouse gas carbon dioxide.

    At the moment, those emissions are calculated in a “bottom-up” fashion.

    By knowing the size of the global fleet, where it moves, the ships’ specifications and how much fuel they are likely consuming – it is possible to estimate how much CO₂, or indeed NO₂, is being pumped into the atmosphere from exhausts.

    But this all involves quite a few assumptions, and so the models need to be audited by some top-down analysis as well – which is where satellites come in.

    S5P-Tropomi does not see CO₂, although its NO₂ observations can act as a tracer in the sense that wherever nitrogen dioxide turns up on shipping lanes, there will be CO₂ present, too.

    But the best solution would be a dedicated carbon-monitoring satellite.

    This is why the EU has asked its technical agent on space matters, the European Space Agency, to design a Sentinel specific to the task.

    Dubbed Sentinel 7 by many people, because that is the next available number in the series, this future mission should fly in the 2020s.

    The aim is to be able track CO₂ down through the atmosphere on a scale of around 3km by 3km, but over a wide area. That would make Sentinel 7 a forceful partner for Sentinel 5.

    Jonathan.Amos-INTERNET@bbc.co.uk and follow me on Twitter: @BBCAmos

Space agencies aim to deliver rocks from Mars to Earth

The US and European space agencies are edging towards a joint mission to bring back rock and soil samples from Mars.

Nasa and Esa have signed a letter of intent that could lead to the first “round trip” to another planet.

The move was announced as a meeting in Berlin, Germany, discussed the science goals and feasibility of a Mars Sample Return (MSR) mission.

The venture would allow scientists to answer key questions about Martian history.

Those questions include whether the Red Planet once hosted life.

Scientists at the Mars meeting said that there was only so much they could learn from Martian meteorites and from the various rovers and static landers sent to the Red Planet.

The next step had to be a mission that would retrieve samples from the Martian surface, blast them into space in a capsule and land them safely on Earth.

  • Europe’s Mars rover takes shape
  • Probe despatched on methane quest

    They could then be subjected to detailed analysis in laboratories, using instruments that are too big and power-hungry to carry as part of a robotic rover’s payload and techniques that are difficult to perform from 55 million kilometres away.

    Making the announcement at the ILA Berlin Air and Space Show, which is taking place at the same time as the Mars science meeting, Dr Thomas Zurbuchen, Nasa’s associate administrator for science, said: “We want to partner with the European Space Agency, but also with other partners.”

    He said this included potential link-ups with the commercial space sector, adding: “We will at every point look at what is available in the commercial market. Nasa has no interest whatsoever in developing things that we can buy.”

    Dave Parker, director of human and robotic exploration at Esa, commented: “It’s very important that every mission we send to Mars discovers something slightly unusual. It’s on the basis of that that we tend to plan the next mission or next missions.”

    Nasa’s 2020 rover mission is expected to help pave the way for Mars Sample Return, by drilling into the surface and caching the cores in containers. But this is intended as a demonstration.

    A mission design would need to be drawn up in coming years. Previous sample return concepts envisaged a rover storing geological samples from scientifically desirable locations on Mars.

    The cached samples would then be loaded on to an ascent vehicle which would lift off from the Martian surface. After the cruise back to Earth, a descent module would parachute down through Earth’s atmosphere, delivering the first retrieved Martian samples directly into the hands of experts waiting on the ground.

    Dr Caroline Smith, head of Earth sciences collections at London’s Natural History Museum, is attending the Berlin meeting. “I would say it’s a reinvigoration of the process,” she told BBC News.

    “Numerous studies have said the only way it’s going to be achieved is through international co-operation. So I think this is a really good message from Nasa and Esa, that we are really going to work together to achieve this – the next frontier of exploration of the Solar System.”

    She added: “There’s a real buzz in the room. I’ve spoken to my colleagues and they’ve said: ‘Wow, we’re really going to do this’!”

    Protecting the planet

    If life existed in the past on the Red Planet, it would likely have been microbial in nature. Scientists want to first know whether conditions were right for life to get started in the past and, if so, whether evidence of fossil microbes remains. They also want to resolve whether there’s life on the Red Planet now. “We’ll only be able to conclusively answer those questions by bringing samples back,” she explained.

    The current high levels of cosmic radiation on Mars’ surface – a consequence of its thin atmosphere – would create a hostile environment for any organisms. But there are ways life might be able to cling on. The possibility that organisms live in the Martian subsurface today means the mission would be subject to strict quarantine, or “planetary protection”, measures.

    “We have to be careful we’re not contaminating Mars with material from our planet, and we want to make sure we’re not accidentally contaminating the samples in a way that would interfere with experiments we want to do on Earth,” explained Dr Smith. She added: “If there’s something hazardous on Mars, we don’t want to accidentally release that into Earth’s biosphere.

    “We are used to handling hazardous materials, whether they be biological or nuclear. There are technologies that exist to be able to handle these in a safe way.”

    Dr Zurbuchen said the sample return mission could also be crucial for later planned human exploration of Mars, which he said Nasa should start thinking about in the 2030s.

    “I can imagine a lot of scenarios where the samples are actually critical for how we explore as humans,” he said.

    For example, scientists want to sample dust from both the atmosphere and soil, because it could have an important impact. If future human “bases” were to rely on solar cells, atmospheric dust might block out sunlight – hampering electricity generation.

    It might also cause problems inside the crew habitats. Dr Smith commented: “If that dust is ubiquitous, and gets everywhere and you’ve got people living there who are breathing in the dust, is it going to be a potential hazard to astronauts?”

    While rocks relevant to the life question are an obvious target for sample return, igneous rocks formed by magma from Mars’ interior are also on the wish-list. “By collecting igneous rocks, we get to understand the geochemical evolution of the planet Mars, we get to know when lavas were being erupted,” said Caroline Smith.

    Analysis of these rocks could help provide a much more accurate chronology for the Red Planet, which currently relies in part on values worked out from studies of the Moon.

    In 2009, Nasa and Esa agreed to collaborate on the Mars Joint Exploration Initiative, which would have culminated in the recovery of samples in the 2020s. But in 2011, Nasa cancelled its participation amid a budgetary squeeze.

    The 2nd International Mars Sample Return Conference is taking place from 25-27 April 2018 in Berlin.

    Follow Paul on Twitter.

    View comments

Rolls-Royce and Boeing invest in UK space engine

Reaction Engines Limited (REL), the UK company developing a revolutionary aerospace engine, has announced investments from both Boeing and Rolls-Royce.

REL, based at Culham in Oxfordshire, is working on a propulsion system that is part jet engine, part rocket engine.

The company believes it will transform the space launch market and usher in hypersonic travel around the Earth.

The new investments amount to £26.5m.

Included in this sum are contributions from Baillie Gifford Asset Management and Woodford Investment Management.

It lifts the total capital raised in the past three years to about £100m. The British government has already put in £60m. BAE Systems initially injected £20m in 2015 and has invested new funds in this latest financial round.

“Rolls-Royce and Boeing – these are really big names, and it’s fantastic to be in this position,” said REL CEO Mark Thomas.

“Rolls are super-positive about the technology. They want us to be independent and innovative, and to push our technology as hard as possible. And Boeing – that’s amazing. They are the world’s biggest aerospace company, have decades of expertise and future plans that, for us I’m sure, will be really exciting,” he told BBC News.

REL is developing what it calls the Sabre engine. This power plant is designed to push a vehicle from a standing start all the way to orbit in a single step.

It would work like a conventional jet engine up to about Mach 5.5 (5.5 times the speed of sound) before then transitioning to a rocket mode for the rest of the ascent.

Key technologies include a compact pre-cooler heat-exchanger that can take an incoming airstream of over 1,000C and cool it to -150C in less than 1/100th of a second. This would permit Sabre to use oxygen direct from the atmosphere for combustion instead of carrying it in a tank with the weight penalty that implies.

Although Sabre is usually talked about in the context of an orbiting spaceplane, it could also be fitted to a vehicle that flies at very high speed from point to point on the Earth’s surface.

This is an application that clearly interests Boeing, whose investment arm, HorizonX Ventures, is driving the tie-up in what is its first investment in a UK-based company.

“As Reaction Engines unlocks advanced propulsion that could change the future of air and space travel, we expect to leverage their revolutionary technology to support Boeing’s pursuit of hypersonic flight,” said HorizonX vice president, Steve Nordlund.

Those who have followed the REL story over the years will be aware that Rolls-Royce is not really a newcomer to the project. The aero-engine giant was involved in Sabre’s precursor years – a spaceplane concept back in the 1980s known as Hotol.

When that hit technical difficulties, Rolls-Royce let its interest go, as did British Aerospace. Both are now back, the latter in its current guise as BAE Systems.

“We are delighted to become a strategic investor in Reaction Engines Limited, an innovative UK company that is helping push the boundaries of aviation technology,” Rolls’ CTO Paul Stein said in a statement.

“We look forward to working with REL and assisting with the development of their technology, and we plan to incorporate this technology into our own future products.”

REL is approaching important demonstration milestones.

In Colorado this summer, it will begin further testing of the pre-cooler technology, confronting it with conditions that simulate the very hot airstreams encountered when vehicles move at hypersonic speeds.

This will be done under contract with the US Defense Advanced Research Projects Agency (DARPA).

Also this summer, REL should take control of its new test facility in the UK at Westcott in Buckinghamshire. It is here that the company will mount a demonstration in 2020 of the full Sabre cycle.

Assuming this goes well, REL would then look to put the technology on some kind of flight vehicle.

The company is expanding fast with more than 160 staff at its Culham HQ. The new investments will allow it to continue the recruitment.

“The team here is outstanding. We have some of the most talented engineers I’ve ever worked with, a high percentage of whom are women engineers; and we have a great apprenticeship programme. It feels like we’re a good-news story and I want to keep it that way,” said Mark Thomas.

Jonathan.Amos-INTERNET@bbc.co.uk and follow me on Twitter: @BBCAmos

View comments

Earth’s magnetic ocean tides mapped from space

This is the European Space Agency’s spectacular new view of ocean tides as they sweep around the Earth.

The movie shows not the bulging movement of water directly, but rather its magnetic signature.

As the Moon pulls the salty seas through our planet’s global magnetic field, electric currents are generated.

And these currents then induce their own magnetic signals, which have now been mapped in exquisite detail by a trio of Esa satellites known as Swarm.

It is a remarkable achievement because the effect is actually very small.

“It’s a really tiny magnetic field. It’s about 2-2.5 nanotesla at satellite altitude, which is about 20,000 times weaker than the Earth’s global magnetic field,” Nils Olsen, from the Technical University of Denmark, told BBC News.

The professor was speaking at the European Geosciences Union General Assembly (EGU) in Vienna, Austria, where a clutch of new Swarm results have been released.

  • When we discovered how the Earth really works
  • Iron ‘jet stream’ sensed in Earth’s core
  • Design call for ‘solar sentinel’ mission

    The mission was sent into orbit in 2013 to bring fresh insight on Earth’s magnetic behaviour.

    Most of the global field is produced by convection of molten iron in the planet’s outer core. But there are secondary components that contribute to the overall signal – such as that coming from the oceans.

    Other satellites will sense the tides as a change in sea-surface height. What is different about the Swarm trio’s magnetic view is that it reveals the movement of the entire water column, right down to the seabed.

    This is important for climate studies. The oceans store and transport vast amounts of heat energy, and getting the more integrated perspective from Swarm enables scientists to build better models of the Earth system.

    There were hopes before Swarm launched that it might even be possible to tease out the magnetism related to specific currents as well, such as the famous Gulf Stream that shifts warm waters across the North Atlantic.

    The desire is still there, but Prof Olsen is a little pessimistic. It is the well-known periodicity of the Moon’s orbit around the Earth that helps betray the tidal signature.

    The Gulf Stream, on the other hand, is a steady flow, and this consistency helps to keep its individual magnetism hidden amongst the much stronger components of the global field.

    One of these bigger signatures is the magnetism retained in the planet’s surface rocks. And Swarm’s most detailed map yet of this aspect was also released at the EGU meeting.

    It incorporates four years of Swarm measurements, data from a previous German spacecraft called Champ, and information gathered by aeroplanes and ships. Regional features as small as 50km across can be discerned.

    Easy to spot are the famous “zebra stripes” at mid-ocean ridges where upwelling magma creates new seafloor and locks the prevailing magnetic field into cooling rock minerals. The discovery of the stripes in the 1960s was a major proof in the theory of plate tectonics.

    “Magnetic fields are one of the keys to understand the sub-surface of the planet, in combination with other pieces of information such as gravity and seismic measurements,” said Rune Floberghagen, Esa’s Swarm mission manager.

    “In the end this will allow us to determine the best ever model of the upper layers of the planet. This is the very clear, sworn ambition of the Swarm mission.”

    The EGU General Assembly has been treated to a bounty of Swarm results to fascinate the specialists. But there is one observation that will certainly have more general interest – that of the position of the north magnetic pole.

    Most people know that it is not aligned with the geographic north pole and instead drifts around.

    Recent decades have seen it shift in a direction that is taking it away from Canada towards Russia. Swarm is watching this movement closely.

    “This year we are in a rather special situation because in 2018 the magnetic pole will be at its closest to the geographic pole. There is a separation of only 390km. The magnetic pole moves at a speed of about 55km per year,” said Prof Olsen. The expectation is that the gap between the two versions of the pole will widen again from next year.

    Jonathan.Amos-INTERNET@bbc.co.uk and follow me on Twitter: @BBCAmos

Map records UK’s small ups and downs

The subtle warping of the land surface across the entire UK has been mapped in detail for the first time.

This view of changing topography was built from more than 2,000 radar images acquired by the European Union’s Sentinel-1 satellites.

It should prove an invaluable tool for policymakers, and for industries working on big infrastructure projects.

The map reveals areas of subsidence and uplift, some of which, like those above old mine workings, could be hazardous.

  • Play with the new map

    Having detailed knowledge of their whereabouts, however, means the risks can now be properly assessed and mitigated.

    For example, it can be seen how sections of the proposed route for the High Speed 2 rail link go across land that is still responding to the presence of coal pits at depth.

    Some of the ground above disused tunnels is descending, while other locations are rebounding as water fills abandoned cavities.

    The motion may be only millimetres per year, but it still needs to be recognised and factored into construction plans.

    • New Sentinel satellite tracks dirty air
    • Space project to monitor all volcanoes

      The deformation map was assembled using a technique called satellite interferometry.

      By overlaying repeat radar pictures of the same location, it becomes possible to discern even the smallest changes in a scene.

      Developed some 25 years ago, the approach always worked best where the spacecraft could see specific hard features time and time again.

      These “persistent scatterers” would be objects like the corners of city buildings. But a few years ago scientists from the University of Nottingham found a way to also capture changes where “soft” features, such as vegetation, dominated the landscape.

      Using this Intermittent Small Baseline Subset (ISBAS) analysis, it is now possible to frame a full picture of Britain that incorporates both urban and rural terrain.

      Geomatic Ventures Limited (GVL) is the company that has been spun out from the university to commercialise the technology. Its chief technical officer, Dr Andy Sowter, told BBC News: “Persistent scattering interferometry relies on points that absolutely persist through all observations, but with the Sentinel satellites we now have so many images that we can use points that persist only perhaps through two-thirds of the observations.

      “In the past this data would have been thrown away, but we’re able to be more selective, and that allows us to get at the full dynamic landscape for the first time.”

      It has to be said, there are groups in the satellite interferometry community that are yet to be convinced by ISBAS. These teams believe that tracking change in vegetated areas is still a major challenge.

      “While this initial map shows the potential power of Sentinel-1 for deformation monitoring on a nationwide-scale, many in the community have legitimate concerns about the reliability of these particular results, especially outside urban areas,” commented Prof Tim Wright from the University of Leeds.

      The resolution of the map is about 90m. It will not show the movement in someone’s backyard, but it can notice the major deformation features.

      The map will be scoured for widespread compaction of soils, landslides, eroding coastlines, and the subsidence over landfill and underground works.

      For the public release of the map, GVL has highlighted some examples of interest.

      These include a 500m-wide zone of depression at Kennington Park, part of the Northern Line tube extension in London. This subsidence is most probably related to the sinking of a shaft that was completed in November 2017.

      In the far north of Scotland, GVL has been monitoring the peatlands of Caithness and Sutherland – the so-called Flow Country. Subsiding bogs release greenhouse gases and so the satellite imagery is a way to keep a check on the UK’s climate commitments.

      “Probably the weirdest example we’ve come across is the 2cm per year uplift at a place called Willand in Devon. It’s a small place on the M5 motorway. We’ve spoken to the Environment Agency and the British Geological Survey, and right now we can’t explain it. We don’t know why it’s going up,” said Dr Sowter.

      The map was put together over a two-year period from 2015 to 2017. But it is essentially now an operational product that could easily be updated every three months.

      What makes this kind of offering possible is the avalanche of data being delivered from orbit by the EU’s Sentinel satellite series. Six spacecraft have so far been launched to image the Earth in a variety of ways, not just radar. A further 14 are already funded to fly.

      All the data is deliberately free and open so that outfits such as GVL can exploit it and innovate new business applications.

      Dr Josef Aschbacher is the director of Earth observation at the European Space Agency, which procures and manages the Sentinels for the EU.

      Speaking here at the European Geosciences Union (EGU) General Assembly in Vienna, Austria, he projected an explosion of data in the years ahead.

      “Today we are producing 14 terabytes of data from the Sentinels alone. We are producing more data from our satellites than all the images and videos being uploaded to Facebook every day,” he told BBC News.

      He said his agency expected to be archiving some 100 petabytes of data by 2026 – all of it available to drive new services such as deformation mapping.

      Jonathan.Amos-INTERNET@bbc.co.uk and follow me on Twitter: @BBCAmos

Iron Age study targets British DNA mystery

A project to sequence DNA from about 1,000 ancient remains could resolve a genetic mystery involving people from south-east Britain.

A recent study showed that the present-day genetic landscape of Britain was largely laid down by the Bronze Age.

But Prof David Reich told the BBC that this wasn’t the end of the story.

During the Iron Age or Roman Period, the DNA of people in the south-east diverged somewhat from that of populations in the rest of the Britain.

Prof Reich, from Harvard Medical School in Boston, told BBC News: “We are initiating an effort to follow up on this observation – and more generally to provide a fine-grained picture of population structure of Iron Age and Roman Britain – using a study that will be on a scale of 1,000 newly reported British samples.”

Read the full interview with David Reich

This, he explained, “would be far larger than any previously reported dataset”.

For comparison, the total global data-set of DNA sequences from ancient human remains currently stands at about 1,400 individuals.

The migration of people associated with the Beaker culture from continental Europe into Britain at the end of the Neolithic period (around 4,000 years ago) remains the most significant event to shape the genetics of subsequent populations on the island.

The Beakers are intimately associated with the introduction of metal-working to Britain. They largely replaced the existing population of farmers who had built Stonehenge and other impressive monuments around the country.

But at some point after the Bronze Age, groups in the south-east appear to have mixed with a population similar to those Stonehenge builders who inhabited Britain before the Beakers arrived.

Most people from south-east Britain still trace most of their ancestry to the Beaker people, but the later mixing event had a bigger impact than Medieval Anglo-Saxon migrations – traditionally seen as the foundation point of English history.

Prof Reich said his team currently had three working hypotheses to explain the result. While the Beakers replaced around 90% of the ancestry in Britain, it’s possible that a pocket (or pockets) of Neolithic farmers held out in isolation somewhere for hundreds of years.

During the Iron Age (which began around 3,000 years ago), they mixed back in with the general population, diluting the Beakers’ genetic background with a type of ancestry that’s now stronger around the Mediterranean than in Northern or Central Europe.

Alternatively, the genetic data may be hinting at a separate migration from continental Europe during the Iron Age – perhaps one that brought Celtic languages into Britain.

The third possibility is that scholars have simply underestimated the genetic impact of the Roman occupation, which lasted in Britain from AD 43 until 410. Roman settlers from the Italian peninsula would have traced a large proportion of their ancestry to Neolithic farmers like those that inhabited Britain before the arrival of the Beaker people.

Follow Paul on Twitter.

Tech trials to find Antarctica’s ‘missing’ iron meteorites

The project to find Antarctica’s “missing meteorites” is making excellent progress, say scientists.

A group led from Manchester University is developing detection equipment it believes will discover a bounty of iron space objects buried in the polar ice.

This survey gear has just come through a week of successful trials.

Presently, 10 times fewer iron meteorites are found in Antarctica compared with other parts of the globe.

The scientists say this discrepancy has nothing to do with differing fall rates; rather, it can be explained simply by the tendency of metal objects to sit just under the ice surface out of the view of collectors.

The team’s equipment, adapted from mine-detection technology, was dragged behind a snowmobile across a simulation field set up at the Ny-脜lesund research base on Svalbard in the Arctic.

Dummy meteorites were hidden in a glacier at varying depths and then the system driven over them to locate their positions.

“It’s gone really well,” said Dr Geoff Evatt. “We’ve got the mechanics of the detector pretty nailed down in terms of the towing, the data-logging, the GPS coordinates – the way we use the system.

“There’s the inevitable teething problems, of course, in making sure the equipment all works with the environment in the cold, but the only way to sort out those problems is to get out here and start using the detector, he told BBC News”

  • Why iron meteorites don’t show themselves
  • Antarctica’s warm underbelly revealed

    Of the more-than-35,000 meteorites catalogued in collections worldwide, something like two-thirds have been retrieved from Antarctica.

    Not only does the colour contrast make for easier prospecting, but hunters also get a helping hand from the way the ice sheet moves. Meteorites that crash in Antarctica’s high interior are buried and transported towards the coast, ultimately to be dumped in the ocean.

    But if this conveyor happens to run into a barrier on the way – such as a range of mountains – the ice will be forced upwards and scoured by winds to reveal its cargo.

    Meteorite hunters on the continent concentrate their searches in these special “stranding zones”.

    What they have noticed, however, is a bias towards stony-type space rocks.

    The iron ones are underrepresented compared with the global distribution. Modelling work by Dr Evatt and his team suggests the metal meteorites are still there; they just do not come back to the surface in the same way.

    It is thought that as they start to rise through the ice, their iron absorbs energy from the Sun and efficiently warms the meteorites’ undersides, enabling them to sink back down.

    Manchester team-member, Dr Katherine Joy will be heading out to Antarctica later this year on an initial survey to assess the stranding zones.

    Places with the highest density of stony-type meteorites sitting on the surface should also be the locations with the greatest number of iron meteorites hidden in the ice below.

    “A reconnaissance trip will help the team investigate which blue icefields that have not been visited before are productive for meteorite collection,” she said.

    “The outcomes of this initial search will help us to target where to take the full detector setup to test for buried meteorites.”

    This is likely to happen in the austral summer of 2019/2020. But working in these remote locations will be extremely challenging and will require the assistance and expertise of the British Antarctic Survey.

    Equipment failure is an ever-present hazard and the team knows it has to go with a detector that is robust and simple to use.

    “Ny-脜lesund has been reasonably comfortable so if we’ve needed to pop up a lid on the equipment and get our hands dirty with the electronics, we can,” said Dr Evatt.

    “We’ve also been able to come back to the base in the evening and make fine adjustments. However, when we use this system in anger in Antarctica, we won’t have those luxuries. The aim therefore is to develop a system with minimal switches and user interface, and one that is robust not just to the environment but to human error.”

    The hope is that iron meteorites “numbering in the low tens” can be recovered on the 2019/2020 expedition.

    These will be brought back to Manchester to be curated and studied.

    Iron meteorites are interesting because they represent the smashed up innards of bodies that almost became planets at the start of the Solar System.

    They therefore provide clues about events that occurred some 4.6 billion years ago when the Earth was forming.

    Jonathan.Amos-INTERNET@bbc.co.uk and follow me on Twitter: @BBCAmos

Climate change dials down Atlantic Ocean heating system

A significant shift in the system of ocean currents that helps keep parts of Europe warm could send temperatures in the UK lower, scientists have found.

They say the Atlantic Ocean circulation system is weaker now than it has been for more than 1,000 years – and has changed significantly in the past 150.

The study, in the journal Nature, says it may be a response to increased melting ice and is likely to continue.

Researchers say that could have an impact on Atlantic ecosystems.

Scientists involved in the Atlas project – the largest study of deep Atlantic ecosystems ever undertaken – say the impact will not be of the order played out in the 2004 Hollywood blockbuster The Day After Tomorrow.

But they say changes to the conveyor-belt-like system – also known as the Atlantic Meridional Overturning Circulation (Amoc) – could cool the North Atlantic and north-west Europe and transform some deep-ocean ecosystems.

That could also affect temperature-sensitive species like coral, and even Atlantic cod.

Scientists believe the pattern is a response to fresh water from melting ice sheets being added to surface ocean water, meaning those surface waters “can’t get very dense and sink”.

“That puts a spanner in this whole system,” lead researcher Dr David Thornalley, from University College London, explained.

The concept of this system “shutting down” was featured in The Day After Tomorrow.

“Obviously that was a sensationalised version,” said Dr Thornally. “But much of the underlying science was correct, and there would be significant changes to climate it if did undergo a catastrophic collapse – although the film made those effects much more catastrophic, and happening much more quickly – than would actually be the case.”

Nonetheless, a change to the system could cool the North Atlantic and north-west Europe and transform some deep-ocean ecosystems.

That is why its measurement has been a key part of the Atlas project.

Scientists say understanding what is happening to Amoc will help them make much more accurate forecasts of our future climate.

Prof Murray Roberts, who co-ordinates the Atlas project at the University of Edinburgh, told BBC News: “The changes we’re seeing now in deep Atlantic currents could have massive effects on ocean ecosystems.

“The deep Atlantic contains some of the world’s oldest and most spectacular cold-water coral reef and deep-sea sponge grounds.

“These delicate ecosystems rely on ocean currents to supply their food and disperse their offspring. Ocean currents are like highways spreading larvae throughout the ocean and we know these ecosystems have been really sensitive to past changes in the Earth’s climate.”

To measure how the system has shifted over long timescales, researchers collected long cores of sediment from the sea floor.

The sediment was laid down by past ocean currents, so the size of the sediment grains in different layers provided a measure of the current’s strength over time.

The results were also backed up by another study published in the same issue of Nature, led by researchers from the Potsdam Institute for Climate Impact Research in Germany.

This work looked at climate model data to confirm that sea-surface temperature patterns can be used as an indicator of Amoc’s strength and revealing that it has been weakening even more rapidly since 1950 in response to recent global warming.

The scientists want to continue to study patterns in this crucial temperature-regulating system, to understand whether as ice sheets continue to melt, this could drive further slowdown – or even a shutdown of a system that regulates our climate.

Follow Victoria on Twitter

Nazi legacy found in Norwegian trees

The relentless campaign to find and sink Germany’s WWII battleship, the Tirpitz, left its mark on the landscape that is evident even today.

The largest vessel in Hitler’s Kriegsmarine, it was stationed for much of the war along the Norwegian coast to deter an Allied invasion.

The German navy would hide the ship in fjords and screen it with chemical fog.

This “smoke” did enormous damage to the surrounding trees which is recorded in their growth rings.

Claudia Hartl, from the Johannes Gutenberg University in Mainz, Germany, stumbled across the impact while examining pines at Kåfjord near Alta.

The dendrochronologist was collecting wood cores to build up a picture of past climate in the area. Severe cold and even infestation from insects can severely stunt annual growth in a stand, but neither of these causes could explain the total absence of rings seen in some trees dated to 1945.

A colleague suggested it could have something to do with the Tirpitz, which was anchored the previous year at Kåfjord where it was attacked by Allied bombers.

Archive documents show the ship released chlorosulphuric acid to camouflage its position.

“We think this artificial smoke damaged the needles on the trees,” Dr Hartl told BBC News.

“If trees don’t have needles they can’t photosynthesise and they can’t produce biomass. In pine trees, needles usually last from three to seven years because they’re evergreens. So, if the trees lose their needles, it can take a very long time for them to recover.”

In one tree, there is no growth seen for nine years from 1945. “Afterwards, it recovered but it took 30 years to get back to normal growth. It’s still there; it’s still alive, and it’s a very impressive tree,” Dr Hartl said.

In other pines, rings are present but they are extremely thin – easy to miss. As expected, sampling shows the impacts falling off with distance. But it is only at 4km that trees start to display no effects.

The Tirpitz sustained some damage at Kåfjord. However, a continuous seek-and-destroy campaign eventually caught up with the battleship and it was sunk by RAF Lancasters in late 1944 in Tromso fjord further to the west.

Dr Hartl believes her “warfare dendrochronology” will find similar cases elsewhere.

“I think it’s really interesting that the effects of one engagement are still evident in the forests of northern Norway more than 70 years later. In other places in Europe, they also used this artificial smoke and maybe also other chemicals. So perhaps you can find similar patterns and effects from WWII.”

The Mainz researcher presented her research here at the European Geosciences Union (EGU) General Assembly in Vienna, Austria.

Jonathan.Amos-INTERNET@bbc.co.uk and follow me on Twitter: @BBCAmos