Humans

Honeycomb, or cinder toffee, isn’t difficult to make, but it reveals the complex science involved in transforming sugar into confectionery, explains Sam Wong

Humans

28 December 2022

By Sam Wong
Getty Images/iStockphoto
HONEYCOMB, or cinder toffee, is simple to make, but is a great example of the complex science involved in transforming sugar into confectionery.
The process begins by heating sugar and water. While pure water boils at 100°C (212°F), the boiling point of a sugar solution is higher. As the solution boils, water evaporates, but the sugar remains, increasing the concentration and raising the boiling point further. At 170°C (338°F), the sugar starts to caramelise: the molecules break apart and recombine, turning it brown and producing delicious flavour molecules.
By measuring the temperature of a boiling sugar … More

In a future where climate change has devastated Florence’s iris fields, a perfumer makes a hard choice in the Hugo award-winning novelist Arkady Martine’s short story

Humans

14 December 2022

By Arkady Martine
Bekologic
Elena could give the lecture half-asleep. She’d done it more than once: earbuds shoved in haphazard in the dark and micbead balanced on her sternum, the rest of her cocooned in 30 pounds of weighted blanket. Warm, serene and bodiless. When she needed to do an onboarding for someone in a time zone radically askew to her circadians, she’d even skip VR. The lecture didn’t need an image, just a voice. In Elena’s opinion, it worked better with just a voice. She had the data analytics to prove it, and those data analytics earned her the top end of her salary band. … More

My mental health cratered this year after the death of my wife, Clare. Getting out into the natural world has helped me to cope, says Graham Lawton

Humans

| Columnist

14 December 2022

By Graham Lawton
Lake Edward in Queen Elizabeth National Park, UgandaRadek Borovka/Shutterstock
I WON’T mourn the passing of 2022. It has been an annus horribilis for me, my family and our friends. Clare, my life partner of nearly 30 years, wife for 24 of them and mother of my three children, ended her own life in August after enduring a chronic pain syndrome for the best part of a year. I became her carer as her pain spiralled into an abyss of torture. I tried everything I could to save her life, but I failed. … More

The land of Punt, a mysterious place where ancient Egyptians bought gold, incense and other luxury items, has been located using DNA from mummified baboons

Humans

14 December 2022

By Colin Barras
Antonio Sortino
WHERE do you find a gift for the pharaoh who has it all? The ancient Egyptians knew: suitably lavish goods were available in Punt. In this mysterious, far-flung land you could obtain all the gold, frankincense and myrrh a pharaoh might desire. To top it off, you could even throw in a baboon or two.
We have long known of the existence of Punt, a trading partner of the ancient Egyptians that provided them with expensive jewels, spices, ivory and animals. But hieroglyphic texts are frustratingly vague regarding the whereabouts of this extraordinary land, which means the hunt for Punt is one of the unsolved puzzles of Egyptology. Now, finally, we may be zeroing in on an exact location. Surprisingly, the clinching evidence isn’t some newly discovered ancient map. Instead, it comes – quite literally – from the mouth of one of Punt’s baboons.
The ancient Egyptians first began sailing to Punt about 4500 years ago, visiting the land infrequently for 1300 years. In Punt, the Egyptians could trade their grain, linen and other goods for aromatics, hardwoods and all manner of exotic products that were difficult or impossible to find in Egypt. “Some scholars describe the Egypt-Punt trade relationship as the origin of international peaceful commerce,” says Nathaniel Dominy at Dartmouth College in New Hampshire. “So it’s a big deal.”
But there is another side to Punt. Consider The Tale of the Shipwrecked Sailor, an approximately 4000-year-old ancient Egyptian text that has been described as the world’s earliest work of fiction. The story tells of a sailor marooned on a fantasy island. There, he meets a gigantic serpent that identifies … More

A study conducted in mice suggests certain gut bacteria can regulate motivation to exercise by increasing dopamine levels in the brain during physical activity

Humans

14 December 2022

By Grace Wade
The gut may play a roll in our motivation to exerciseJacob Lund/Alamy
Motivation to exercise may come from the gut in addition to the brain. A study in mice finds that certain gut bacteria can increase the release of dopamine during physical activity, which helps drive motivation.
Though most of us know that exercise comes with many benefits, how much people exercise varies widely, says Christoph Thaiss at the University of Pennsylvania. He and his colleagues wanted to identify physiological factors that may explain this variation.
They collected data from 106 mice on exercise capacity, genetics, gut microbiome composition and more, and fed it to a machine learning model for analysis. The model found that how often mice exercised was most strongly associated with the makeup of their microbiome.Advertisement
In a series of experiments that followed, the researchers found that mice with depleted gut microbes spent about half as much time voluntarily running on a wheel as those with intact microbiomes. What’s more, they had reduced dopamine levels in their brains during physical activity, suggesting they found exercise less rewarding. The team then repeated these experiments in mice that had intact microbiomes but lacked neurons connecting the gut to the brain and found this resulted in the same effects seen in mice with depleted microbiomes. Together, these findings show the gut plays an integral role in motivation for exercise, Thaiss says.
The team also identified molecules produced by certain gut bacteria called fatty acid amides that, when given to mice with depleted microbiomes, restored how often they exercised to levels seen in mice with intact microbiomes. “Surprisingly, the motivation for exercise is not brain-intrinsic but is regulated by the gastrointestinal tract,” says Thaiss.
This isn’t the first time the microbiome has been found to play a role in functions outside our gastrointestinal system. In fact, previous studies have shown that the bacteria in our guts may influence our mood, control blood sugar levels and even protect against inflammation linked to conditions like heart disease and dementia.
However, it is too early to know if these findings in mice are also true for humans, Thaiss says. He and his team are currently conducting a similar trial in people to see whether we have the same gut-to-brain pathway, and if so, whether leveraging it will boost our motivation to exercise.
Journal reference: Nature, DOI: 10.1038/s41586-022-05525-z

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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’re made from rubber, human brains are softer and squishier. Their ability to resist pressure is like that of a slab of gelatine, and they break apart more easily than polystyrene foam used for packaging.
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 resiliency.
Combining a machine learning algorithm with MRI scans of people lying face down and then face up to shift the location of the brain in the skull, the researchers 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 collapses up to 10 times more easily than 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 – meaning its squishiness is comparable to a slab of gelatine. 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 impact 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 their model can now be used to predict brain shifts that will occur doing 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.
Reference: Journal of the Royal Society Interface, DOI: 10.1098/rsif.2022.0557

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