Humans

Waste water contains a treasure trove of data on our health, well-being and inequality, and can be used to head off epidemics, track pandemics and even spot new designer drugs before their effects show up in the population. But how much information are we willing to flush down the toilet?

Humans

16 August 2022

By Claire Ainsworth
The countless chemicals and pathogens that you flush away end up in your nearest sewage treatment plantAbstract Aerial Art/Getty Images
WHAT’S the largest source of mass moving in and out of a city every day? You think, if it’s a port city, it must be boats – or, you know, maybe if it’s a landlocked city, it’s trains or trucks or cars or planes. No, it’s water. It’s water. There’s so much more water moving in and out of a city any day than there is any kind of cargo. It’s basically pure water coming in. And then the water that leaves has some traces of almost every human activity that’s going on in the city.”
Once Eric Alm is in full flow, it is hard to stop him. But it isn’t hard to understand his enthusiasm. Alm, a biological engineer at the Massachusetts Institute of Technology, is one of a growing band of researchers turning their attention to the fluid coursing through our sewers. This waste water, as it is known, contains the whispered biochemical confessions of millions of people, and by listening to them, scientists can paint surprisingly detailed pictures of our health, wealth and environment, head off epidemics, track pandemics and even spot new “designer” drugs before their effects show up in the population.
Water treatment plantSuriyapong Thongsawang/Getty Images
The field, called waste water-based epidemiology, not only has the potential to revolutionise public health but also transform our view of sewage from disgusting waste to … More

Unlike people, 43 species of monkeys and apes are known to have so-called vocal membranes, which may prevent them from having precise voice control

Humans

11 August 2022

By Clare Wilson
Unlike in other primates, the human voice box has lost small tissue structures called vocal membranes, which may have been involved in the evolution of speechSEBASTIAN KAULITZKI/SCIENCE PHOTO LIBRARY
The loss of small tissue structures from the voice box may have been essential for the evolution of human speech.
In a study of 43 non-human primates, all the animals had “vocal membranes”, a small extension of the throat’s vocal cords that makes their sounds louder and higher but also more irregular and harder to control.
As humans lack vocal membranes, this suggests they were lost when our ancestors diverged from chimpanzees to allow more precise voice control, says Tecumseh Fitch at the University of Vienna in Austria.Advertisement
While many animals make calls to communicate, the evolution of complex human speech seems to have required anatomical changes, as well as changes in the brain. In humans, the vocal cords are flaps of tissue in the throat that vibrate as air is expelled from the lungs, allowing us to make “voiced” sounds, as opposed to breathy ones.
We already knew that a few species of monkeys and apes have vocal membranes. To better understand the loss of these structures in humans, Fitch’s team looked at the voice box, also known as the larynx, of 43 species of apes and monkeys. This was done by carrying out magnetic resonance imaging (MRI) or computed tomography (CT) scans on dead or anaesthetised animals in the first such large-scale study of primates. The researchers found that all 43 species had this vocal cord extension.
The team also analysed video footage that showed the voice box of an anaesthetised chimpanzee with an endoscope in its throat while the animal made grunts and growls as it was waking up. They did the same for anaesthetised rhesus macaques and squirrel monkeys that were stimulated to make noises by having an electrode put into the part of their brain that causes them to produce vocalisations.

The researchers found that in all these animals, vibration and collision of the vocal membranes are the primary source of their calls, as their vocal cords were in motion less often.
If humans still had vocal membranes, our speech would probably sound more rough and variable, with abrupt pitch changes, like someone with laryngitis, says Fitch.
“A key thing that distinguishes human speech from animal sounds is our fine-grained control over the sounds we make. That is only possible if our vocal apparatus is easy for our brains to control,” says Richard Futrell at the University of California, Irvine. “If the system is complex, then it will behave in a way that is chaotic and unpredictable.”
But Adriano Lameira at the University of Warwick in the UK says many apes and monkeys make both loud and irregular calls as well as some quieter and more controlled noises. “The alleged limiting effect [of vocal membranes] on primate vocal production seems exaggerated,” he says.
Journal reference: Science, DOI: 10.1126/science.abm1574

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Feedback is our weekly column of bizarre stories, implausible advertising claims, confusing instructions and more

Humans

10 August 2022

Josie Ford
Hair-raising heirloom
Tidying the stationery cupboard throws up many archaeological treasures, but nothing so exciting, or terrifying, as the discovery made by a gentleman sorting through his deceased brother’s attic in Kent the other day. He found a head.
This Egyptian mummy’s remains, brought to England as a souvenir, must have been passed down the family line for several generations. You would think it might have come up in conversation now and again. But no: the discoverer, who has gifted the grisly object to Canterbury Museums and Galleries, says he knew nothing about it. A CT scan has established that … More

When it comes to human physiology, behaviour and social interaction, it is time to abandon a 200-year hunt for normal people, argues Sarah Chaney in her new book

Humans

10 August 2022

By Simon Ings
Henrik Sorensen/Getty images
Am I Normal?
Sarah Chaney
Wellcome Collection
A PAIR of unusual gloves, belonging to 19th-century polymath Francis Galton, lie in University College London. Galton was the man who coined the term eugenics to describe beliefs and practices that aim to “improve” the genetic quality of a human population.
His motto was “whenever you can, count”, so he decided to put a pin in the thumb of his left glove and a felt pad, covered by a strip of paper, across its fingers. By touching different fingers with the pin, Galton could track the things he saw without others noticing.
One … More

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Look Both Ways stars Lili Reinhart as Natalie, whose life splits into parallel realities on the eve of her graduation. She either heads to Los Angeles to pursue a career, or stays at home with her baby. On Netflix from 17 August.
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Existential Physics speaks to the big stuff: is the universe compatible with God? Does free will exist? Theoretical physicist Sabine Hossenfelder shows how the latest research gives insight into age-old problems. On sale from 18 August.

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The Neuroscience of Creativity is revealed by neuroscientist Jonathan Iliff, who explores … More

Based on the book by journalist Sheri Fink, this TV mini-series dramatises the shocking stories of health workers and patients whose lives are changed forever as Hurricane Katrina overwhelms a US hospital in 2005, finds Bethan Ackerley

Humans

10 August 2022

By Bethan Ackerley
Anna Pou (Vera Farmiga), front, and Karen Wynn (Adepero Oduye)Courtesy of Apple
Five Days at Memorial
Apple TV+
ON 11 September 2005, 45 bodies were recovered from Memorial Medical Center, New Orleans. The hospital had been hit by Hurricane Katrina, then the most devastating storm in US history. Patients, staff and their families were stranded for five days by floodwaters. Conditions were apocalyptic. Deaths were expected.
The aftermath brought uncomfortable revelations. Some bodies contained potentially dangerous levels of morphine and other drugs. The actions of Anna Pou, a doctor at the hospital, were … More

When a beaked whale carcass washed up near her home, part of a mass stranding around the region, Mhairi Killin was inspired to launch an artistic challenge to the military’s impact in the area

Humans

10 August 2022

By David Stock
A “constellation” of data points showing where the dead whales washed upMhairi Killin
On Sonorous Seas
An exhibition led by Mhairi Killin in collaboration with others
An Tobar, Isle of Mull, UKCloses 27 August
SOMETIMES art and science come together to raise our awareness of a compelling issue. One such occasion is a multimedia exhibition called On Sonorous Seas, led by artist Mhairi Killin and prompted by her experience of a mass stranding of dead whales.
At the An Tobar gallery on the Isle of Mull in the Inner Hebrides, UK, … More

Metal-making practices described in a 2300-year-old text called the Kaogong Ji are more sophisticated than anyone realised

Humans

10 August 2022

By Jason Arunn Murugesu
A Chinese bronze container from the fifth century BCB Christopher / Alamy
THE missing ingredients of an ancient Chinese recipe for bronze may have been uncovered, revealing another level of sophistication in the practice of chemistry at the time.
Kaogong Ji, a 2300-year-old text, is the oldest technical encyclopedia in the world. The book contains instructions on how to make several objects, such as metal drums, chariots and weapons. It also contains six recipes for bronze that have long puzzled researchers.
While bronze-making wasn’t unique to China at that time, Ruiliang Liu at the British Museum in London says the style and scale of the bronzes produced there was unrivalled.Advertisement
“We asked ourselves, how can Asian and Chinese people manage to produce so many bronzes [at that time],” says Liu.
Bronze is typically made by combining copper and tin. The recipe mystery centres on two ingredients called jin and xi that researchers have been unable to identify. In modern Mandarin, jin means gold, but in antiquity it is believed to have referred to copper or a copper alloy. Meanwhile, xi has long been considered to refer to tin.
But chemical analyses of bronze vessels from that time period suggest that jin and xi can’t simply be copper and tin.
Liu and his colleagues analysed previously compiled data on the chemical composition of knife-shaped Chinese coins produced in the same era as when the recipes were recorded. By teasing out the relationships between the metals present in the coins, the researchers suggest the objects were created using pre-made alloys.
They discovered that the higher the lead concentration in the coins, the lower the concentration of both copper and tin. The coins with the highest concentration of copper also had the highest concentration of tin. These findings suggest that lead was being mixed into an alloy of copper and tin – a bronze alloy.
By modelling different combinations, the team determined that an 80:15:5 copper-tin-lead alloy mixed with a 50:50 copper-lead alloy in various ratios was the best match with the chemical coin data.
These pre-made alloys are likely to be jin and xi respectively as recorded in the Kaogong Ji, says Liu. But he adds that the recipes in the book may not reflect how bronze was usually made.
“If anything, the recipes are too specific,” he says. “The people who actually got their hands dirty probably couldn’t read or write so they wouldn’t have been able to record the recipe. I think there is a gap in knowledge between the person who wrote the recipe and the person who did the real work.”
Jianjun Mei at the University of Cambridge isn’t totally convinced by the findings. He says these recipes shouldn’t considered accurate records of practices used at the time. “These officials [who wrote the text] might only pay attention to the most important materials, such as copper and tin, rather than all other materials,” he says. The recipes still largely work if you take jin and xi to be copper and tin, he says.
Bronze was used in ancient China to make large vessels for religious purposes, says Jessica Rawson at the University of Oxford. “In China, they had a huge workforce and so could afford to use a very complicated system with a lot more metal than in the West,” she says.
Journal reference: Antiquity, DOI: 10.15184/aqy.2022.81).

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