Humans

Researchers used MRI scans and an algorithm to measure the stiffness and resilience to pressure of the brain in living people

Humans

14 December 2022

By Karmela Padavic-Callaghan
Brains are surprisingly squishyShutterstock/Teeradej
Though they may look like they are made from rubber, human brains are softer and squishier. Their ability to resist pressure is much less than the polystyrene foam used for packaging, more comparable to that of Jell-O.
Nicholas Bennion at Cardiff University in the UK and his colleagues set out to develop a method for obtaining more accurate measurements of the brain’s physical properties inside living humans. Most of what we know about how brain tissue reacts to instruments touching it during neurosurgery comes from organs that have been cut into or removed and preserved in chemicals, which can affect tissue stiffness and resilience.
The researchers performed MRI scans of people lying face down and then face up to shift the location of the brain in the skull. By analysing this data with a machine learning algorithm, they were able to work out different material characteristics of the brain and tissues that connect it to the skull. They quantified how much the brain collapses when pressed on, how it reacts to being pushed sideways and how springy the connective tissues are.Advertisement
“If you take a brain which hasn’t been preserved in any way, its stiffness is incredibly low, and it breaks apart very easily. And it really is probably a lot softer than most people realise,” says Bennion.
The team found that brain matter can be compressed up to 10 times as easily as polystyrene foam and that its resilience to being pushed sideways is about a thousandth of what it would be if it were made from rubber – its squishiness is comparable to a slab of Jell-O. Bennion says that the algorithm calculated that the tissues connecting the brain to the skull were also fairly soft, possibly to protect the brain from moving too abruptly.
Though researchers have long known that brains are very soft and very fragile, the new study makes that notion precise enough to better inform sensitive surgical procedures, says Ellen Kuhl at Stanford University in California.
The new method, however, may not fully capture the way the brain deforms during motions more violent than shifting positions, such as head trauma in an contact sport or traffic accident, says Krystyn Van Vliet at the Massachusetts Institute of Technology. In these situations, the flow of fluids within the brain can change its material properties.
The team hopes the model can now be used to predict brain shifts that would occur during surgery for each individual patient based on pre-operative MRI scans. This may eliminate the need for inserting and re-inserting instruments into the brain until they hit the correct spot, making procedures less invasive.
Journal reference: Journal of the Royal Society Interface, DOI: 10.1098/rsif.2022.0557

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Would your radiation badge work? What would it be like to witness a nuclear bomb blast? The early uncertain days of the UK’s nuclear test programme are poignantly recalled by service veterans in a series of four films at the Plym to Pamlico exhibition

Humans

13 December 2022

By Laura Cooke
A screengrab from the British Nuclear Test Veterans Association nuclear test films, part of the Plym to Pamlico exhibition.British Nuclear Test Veterans Association
Plym to Pamlico
The Royal Engineers Museum, Gillingham, UK
Until 12 March 2023
From flying through mushroom clouds collecting radioactive samples to waking up in a tent covered in aggressive crustaceans, a new series of films is lifting the lid on what it was like to take part in the UK’s nuclear testing programme in the 1950s and 1960s.
Four short films mix animation with images taken during operations from the … More

By Kismat Shrees
The first archaeological survey of the site of Porvenir, where a century-old massacre occurred at the US-Mexico border, has discovered bullets and cartridge casings for US military weapons.
A ballistics analysis has raised new questions about the role of the US Army in the 1918 Porvenir massacre, where Texas Rangers killed 15 unarmed Mexican boys and men. The new evidence collected by David Keller, an archaeologist at Sul Ross State University in Texas, and colleagues suggest the US army could have played a bigger role in the massacre than previously thought.

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From a bone fragment of a mysterious new species to the latest on cave art, Paul Pettit’s powerful new book shows how science is rewriting the past

Humans

7 December 2022

By Alison George
Upper Palaeolithic art on a replica of the Chauvet cave, south-east FranceAndiA/Alamy
Homo Sapiens Rediscovered
Paul Pettitt (Thames & Hudson)
WHO are we? This fundamental question has always exercised humanity. One way to approach it is to look at our origins and the evolutionary journey we have taken. Today, thanks to powerful new tools, we can look at the lives of our ancestors in unprecedented detail: the meals they ate, their relationships. And through their art and other practices, we can even get hints about their beliefs about the world.
Paul Pettitt, … More

Spotlight on plankton, the ocean’s fascinating, bite-sized creaturesEvery night, plankton take a journey to shallower waters to feed, prompting predators to follow in search of a very small, but tasty, snack. These images are taken from a new book, Planktonia, illuminating their daily ascent More

Who you really are is a major question worth pursuing for most people, so research into self-knowledge is important despite the fact it often relies on subjective findings

Humans

| Leader

7 December 2022

Eugenio Marongiu/Cultura Creative RF/Alamy
WHO am I? It is a simple yet profound question, long considered worth grappling with on the basis that self-knowledge is good. Take personality, for instance. Intuitively at least, it makes sense to think that if you know your personality, you will make wiser life decisions, have better relationships and ultimately enjoy greater well-being.
That may be true, but studying how accurately we perceive our personality, the subject of our cover story Self-knowledge: How to know your true personality and why it matters, is fraught with difficulties. The fact is there is no objective perspective on your personality in … More

When it comes to knowing yourself, your own perception of your personality doesn’t necessarily align with that of people around you. But which is more accurate? And can discovering your true nature lead to a better life?

Humans

7 December 2022

By Daniel Cossins
Jason Ford
EVER wondered what other people think of you – I mean, what they really think of you? I consider myself decent company, for instance, even if I know I get a bit vociferous after a few pints of bitter. I like to think I am open-minded and considerate, too, though I recognise I can be dismissive at times. But lately, particularly the morning after a few of those pints, I have become curious about how other people see me.
Let’s be honest: sometimes I wonder if people think I’m more obnoxious than I realise. Because presumably you wouldn’t know. That is partly where the intrigue lies for me. How accurately do we see ourselves? And who is the real you anyway – the person you think you are, or the person other people see?
It isn’t that I am self-obsessed, you understand. I am just intrigued about the extent to which the way people see my personality tallies with the way I view myself. Ultimately, I wonder whether being more aware of these shadowy hinterlands of self-knowledge might make life better – not only for me, but for those who spend time with me. Did I say I wasn’t self-obsessed?
In search of answers, I did what most sensible people tend to avoid: I solicited honest insights into my nature from a dozen friends, family members and colleagues. I asked them to fill out a 60-point questionnaire designed by psychologists to assess personality, and to give the two traits they most associate with me – one positive and one negative. Then I waited nervously for the scales to fall from my eyes.
Personality test … More

By Alison George
A reconstruction of the skull of a Homo naledi childBrett Eloff Photography
Archaeological evidence suggests that Homo naledi, a primitive human species with a chimpanzee-like skull, used fires to cook food and navigate in the darkness of underground caves, despite having a brain one third of the size of ours.
“We have massive evidence. It’s everywhere,” says Lee Berger at the University of the Witwatersrand in South Africa. “Huge lumps of charcoal, thousands of burned bones, giant hearths and baked clay.”
This find, which is still being analysed and remains controversial, could revolutionise our understanding of the emergence of complex behaviours that had been thought to be the sole domain of large-brained species, such as modern humans and Neanderthals.Advertisement
H. naledi was first discovered in 2013 in the Rising Star cave system in South Africa when two cavers managed to enter a hitherto unexplored chamber via an incredibly tight passage. The surface was littered with thousands of fossil bones. In 2015, these were declared to belong to a new species.
We now know that H. naledi was about 144 centimetres tall on average and weighed around 40 kilograms. It had a strange mix of primitive and modern features, with ape-like shoulders, a tiny brain only just bigger than that of a chimpanzee and teeth “more reminiscent of something millions of years old”, says Berger.
Yet dating of its fossil remains in 2017 showed that it lived relatively recently, between 230,000 to 330,00 years ago, meaning that it could have co-existed with Homo sapiens, which evolved in Africa around 300,000 years ago.
A hearth possibly made by Homo nalediLee Berger
But questions remained about how H. naledi navigated through the labyrinth of underground passages at Rising Star, which are in complete darkness and require complex manoeuvres through gaps in the rock just 17.5 centimetres wide.
This inaccessibility means that, in the past decade, only 47 people – all small and slightly built – had managed to access the Dinaledi chamber where H. naledi fossils were first discovered. But in August this year, Berger, who is 188cm tall, decided to risk entering this labyrinth, losing 25 kilograms of weight in preparation.
“It’s not a space made for six-feet-two people like me. I’m by far the largest person who’s even been in,” he says. He knew there was a possibility he might not be able to squeeze out again. “I almost died on the way out,” he says.
The risk paid off. When Berger entered the Dinaledi chamber and looked up, he realised that there were blackened areas and soot particles on the rock. “The entire roof of the chamber is burnt and blackened,” he says.
By coincidence, at the same time that Berger was observing the soot, his colleague Keneiloe Molopyane, also at the University of the Witwatersrand, uncovered a tiny hearth with burnt antelope bones in another part of the cave system, then a large hearth next to it 15cm below the cave floor. Then, in another area called the Lesedi chamber, Berger found a stack of burnt rocks, with a base of ash and burnt bones.
This is a remarkable discovery, as many researchers thought it was impossible for such a small-brained hominin to make and use fire within a cave system. Although we have evidence that ancient humans living in what is now Kenya could control fire as far back as 1.5 million years ago, this capacity “is typically associated with larger-brained Homo erectus”, says Berger.
H. naledi also seem to have used the space in interesting ways, with “body disposal in one space and cooking of animals in adjacent spaces”, says Berger. “The capacity to make and use fire finally shows us how Homo naledi ventured so deep into dangerous spaces, and explains how they may have moved their dead kin into such spaces, something likely impossible without light. It also hints at a complex naledi culture becoming visible to us.”

Dating of the charred remains is still underway, so the decision to announce the fire discovery in a talk on 1 December, prior to the publication of the formal scientific analysis, has proved controversial.
“It’s impossible to evaluate Lee Berger’s claims properly without seeing the full evidence, but apparently that is forthcoming,” says Chris Stringer at the Natural History Museum in London. “With all due respect to Lee and his teams for a series of great finds, this is not the way to conduct science or progress scientific debate about potentially very important discoveries.”
However, for Francesco d’Errico at the University of Bordeaux in France, the discovery that H. naledi may have been able to control fire could give insight into the way they treated their dead and their social organisation.
“If Homo naledi were shown to have mastered fire and used it to gain access to the most remote areas of the Rising Star karst system, this could have very important implications for the interpretation of mortuary practices conducted at the site,” he says. “The control of an artificial light source allows the organisation of actions in space and time and, in the case of mortuary practices, facilitates the participation of several members of the group in collaborative and shared actions.”
Charcoal possibly used by Homo nalediLee Berger
For Berger, the fire-use discovery has implications that are even more revolutionary. If these small-brained humans with many primitive features were capable of the complex cognition required to make and control fire, then “we’re beginning to see the emergence of a cultural pathway and behaviour that we thought, until this moment, was the domain of [Homo sapiens and Neanderthals],” he says.
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