Humans

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Invincible, available from 26 March on Amazon Prime Video, animates Robert Kirkman’s long-running comic about an ordinary teenager whose father just happens to be Omni-Man, the world’s most powerful superhero.

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Rob Dunn, co-author of the new book Delicious with Monica Sanchez, speaks about the deep history of flavour and the role it has played in human evolution. Online from the Royal Institution in London at 7 pm GMT on 23 March.

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A Thousand Brains: A new theory of intelligence by Jeff Hawkins, inventor and neuroscientist, explains how the brain builds not just one model, but hundreds of thousands of models of everything we know.

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Amazon Prime Video
Watch
Invincible, available from 26 March on Amazon Prime Video, animates Robert Kirkman’s long-running comic about an ordinary teenager whose father just happens to be Omni-Man, the world’s most powerful superhero.

Watch
Rob Dunn, co-author of the new book Delicious with Monica Sanchez, speaks about the deep history of flavour and the role it has played in human evolution. Online from the Royal Institution in London at 7 pm GMT on 23 March.

Read
A Thousand Brains: A new theory of intelligence by Jeff Hawkins, inventor and neuroscientist, explains how the brain builds not just one model, but hundreds of thousands of models of everything we know.

More on these topics: More

How old you feel matters for how long you will live. Here’s how you can reduce your psychological age

Health

17 March 2021

By Graham Lawton

People who feel younger than their years tend to live longerskynesher/Getty Images
“AGE is an issue of mind over matter. If you don’t mind, it doesn’t matter.”
This nugget of wisdom, often attributed to Mark Twain, has been turned into many an inspirational internet meme over the years. As a 51-year-old who is starting to feel the gathering momentum of the inevitable slide, it strikes me as little more than a platitude that makes people feel better about getting old.
But according to a growing body of research, there is more to it than that. Subjective age – how old we feel – has a very real impact on health and longevity. People who feel younger than their years often actually are, in terms of how long they have left to live.
The question of what controls our subjective age, and whether we can change it, has always been tricky to address scientifically. Now, research is revealing some surprising answers. The good news is that many of the factors that help determine how old we feel are things that we can control to add years to our lives –and life to our years.
We have known for a while now that simply counting the number of years someone has been alive isn’t necessarily the most accurate way of gauging longevity. Biological “ageing clocks” measure various markers in the body to see how far along the physical ageing process we are (see “Old bones?“). But we also know that physical ageing is not the be-all and end-all. Gerontologists recognise that just as we can make generalisations about the ways that physical ageing affects our bodies – a … More

By Krista Charles

When you fall, your leg muscles activate differently to try to keep you balancedJustin Paget/Getty Images
Miss a step when walking down the stairs and your legs will attempt to recover your balance after the unexpected fall – but how? The key to remaining upright seems to be in the way our calf and foot muscles are activated.
“One of the things we know about human locomotion is our ability to stay on our feet, upright, is pretty remarkable, but we don’t understand a lot about how we achieve this,” says Taylor Dick at the University of Queensland in Australia.

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To find out more, she and her colleagues conducted an experiment that involved attempting to make people fall over. The researchers had 10 people jump in place on top of platforms that were sitting on a device measuring the forces exerted by each foot individually. They then removed the platforms without warning.
As participants tried to retain their balance, the researchers used electromyography and ultrasound sensors on their legs to track muscle activity and changes in muscle length.

They determined that experiencing an unexpected drop automatically increases the timing between when the muscles in our legs and feet first activate and when they reach their shortest length.
This in turn enables the foot muscles to absorb and dissipate energy more effectively, allowing us to recover from the drop.
The team also found that while opposing muscles normally contract in turn when walking, both groups of muscles contract at the same time during an unexpected drop.
In cases where you aren’t able to successfully recover and end up falling, Dick says it may be because a different strategy is used, one that relies on signals travelling from your leg muscles to your brain and then back to your leg muscles. This may take more time than it does to travel the distance to the new “lower” ground.
She hopes that this research can inform the design of lower limb assistive devices, such as prostheses and exoskeletons, that can help people navigate staircases and move over uneven terrain.
Homayoon Kazerooni at the University of California, Berkeley, says that the insights into the timing changes of human muscle activation could lead to better exoskeleton designs, including control algorithms that offer better stability over unpredictable terrain, or at least help with recovering from a fall.
Journal reference: Proceedings of the Royal Society B, DOI: 10.1098/rspb.2021.0201

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By Donna Lu

A large grave in Rennes probably contains soldiers from the French Royal armyColleter et al.
Remains buried in two mass graves in the same cemetery in France have been identified as medieval soldiers belonging to opposing armies.
Rozenn Colleter at the French National Institute for Preventive Archaeological Research and her colleagues have identified the skeletons as belonging to soldiers who fought in the Siege of Rennes in 1491. The skeletons were found buried in a cemetery outside the Jacobin Convent in Rennes.
The researchers identified the skeletons by combining historical information with archaeological techniques, including genetic analysis. They found that … More

By Christa Lesté-Lasserre
There are nerve endings in fingerprint ridges that help us feel things
Leonardo Carneiro de Almeida / Getty
Our fingertips have an extraordinarily high sensitivity to touch – and now it looks like that sensitivity might be largely confined to the ridges of our fingerprints.
“They really help us get very detailed information about what we touch,” says Ewa Jarocka at Umeå University in Sweden.

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Scientists have suspected that our circular, winding fingerprints might have evolved to improve our ability to grip objects by creating better friction, says Jarocka. But she says others have suggested they might contribute to our “very refined sense of touch”.
Because current models can’t explain the high levels of sensitivity people have shown in past scientific studies, Jarocka and her colleagues decided to investigate.
They asked six men and six women between the ages of 20 and 30 to lie comfortably in a dentist chair while their fingers were held in place. The researchers then ran a card covered in tiny, flat-tipped cones, each less than half a millimetre high, over their fingertips at different speeds and in different directions. Meanwhile, they recorded electrical activity of a single nerve cell using tungsten electrodes inserted into a main nerve in each participant’s upper arm.

The results allowed the researchers to map out exactly where on the fingertips the information that was sent to the nerve was collected. These sensitivity hotspots turned out to be very small, each only about 0.4 millimetres wide.
What’s more, these hotspots followed specific patterns on the fingertips – the same ones as the fingerprint ridges. Regardless of how the researchers moved the dotted card over a finger, its hotspot map stayed the same, suggesting the sensitivity zones were “anchored in the very stable structure” of the ridges themselves, says Jarocka.
“We have all those multiple hotspots, and each one responds to the details of 0.4 millimetres, which is the approximate width of the [fingerprint] ridge,” she says. “Then our brain receives all that information. This really offers an explanation to how it’s possible that we’re so dexterous and have such a high sensitivity in our fingertips.”

This doesn’t mean fingerprints might not have other functions as well, however – perhaps including improving grip, says Jarocka. But it does reveal the important role that the ridges play in touch.
“Now that we know that the single neuron can be so sensitive on such a [precise] scale, we can finally explain how people can be so detail-sensitive,” she says.
Journal reference: JNeurosci, DOI: http://dx.doi.org/10.1523/JNEUROSCI.1716-20.2021 More

By Michael Marshall
The way ancient humans hunted may have influenced their evolution
Shutterstock / Gorodenkoff
Our ancestors’ diets changed dramatically over the course of the past 2.5 million years, and one research team thinks that profoundly affected our evolution.
According to a team including Miki Ben-Dor and Ran Barkai at Tel Aviv University in Israel, hominin diets were once so dominated by meat from massive animals that the hunters caused some of those species to go extinct. This, in turn, forced our ancestors to develop more sophisticated hunting techniques to bring down smaller, more elusive prey, leading to greater intelligence and the … More

By Jo Marchant
Fragments of the Antikythera mechanism
Hewlett-Packard/X-Tek Systems
The 2000-year-old Antikythera mechanism, often described as the world’s first computer, was a sophisticated bronze device that modelled the cosmos. Researchers have assumed that pointers were used to represent celestial bodies, moving around a dial like the hands on a clock, but a new study suggests that these were instead shown using a series of bejewelled, rotating rings.
The machine dates to the first century BC and was discovered in a shipwreck near the Greek island of Antikythera in 1901. Scientists have spent more than a century decoding its battered remains, which include inscriptions, measuring scales and more than 30 bronze gearwheels.

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Modern reconstructions based on detailed X-ray images of the surviving pieces show it was a box around 30 centimetres high, operated by turning a handle on the side. On the back were two spiral dials, showing a calendar – including the timing of the Olympics – and dates of predicted lunar and solar eclipses.
Much of the front part of the mechanism is missing, but researchers agree that a large circular dial once displayed the motions of celestial bodies through the sky. Complex trains of gearwheels calculated the back-and-forth motion of the planets as seen from Earth, as well as the variable speed of the sun and moon.
Inscriptions deciphered in 2016 revealed that Venus and Saturn were represented by mathematical cycles not previously known from ancient Greek astronomy. For example, the Greeks are known to have described the back-and-forth motions of Venus using an 8-year cycle, or a more accurate 1151-year cycle, but the inscriptions on the Antikythera mechanism describe a 462-year cycle.

Tony Freeth at University College London and his colleagues suggest that the Greeks could have deduced this from the known cycles using a step-by-step arithmetic method originally described by the philosopher Parmenides in the 5th century BC. They used the same method to derive similar cycles for the other planets, for which the inscriptions are missing, and constructed a new gearing scheme that they claim fits all the available physical evidence, including a previously unexplained 63-tooth gearwheel and the surviving inscriptions.
The researchers conclude that the celestial bodies weren’t represented using pointers, but instead by concentric rotating rings. The inscriptions hint that coloured, semi-precious stones may have shown the position of each planet on its ring.
Freeth says he is confident that the new scheme “is essentially right” and describes it as “a beautiful system”. He thinks the mechanism could have been used to calculate the outcomes of astronomical theories, instead of working out the maths by hand. “It was a prediction machine,” he says. “You just turn the handle and it shows you.”

Mike Edmunds at Cardiff University in the UK, who has worked on the Antikythera mechanism, says the proposal is “ingenious” but cautions that with so few surviving clues, it is impossible to know for sure whether any theoretical reconstruction mirrors the original.
He also notes that the newly proposed design involves many extra gearwheels, and wonders whether such a complex mechanism could have turned smoothly and operated for long periods without breaking.
Freeth says the team’s next challenge is to make a physical model using 2000-year-old techniques, to prove it really would work.
Journal reference: Scientific Reports, DOI: 10.1038/s41598-021-84310-w
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