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Modern surgery began with saws and iron hands – how amputation transformed the body in the Renaissance



theconversation.com – Heidi Hausse, Assistant Professor of History, Auburn – 2024-06-17 07:13:41

Amputees in 16th century Europe commissioned iron hands from artisans, many of whom had never made prostheses before.

Lernestål, Erik, Livrustkammaren/SHM, CC BY-SA

Heidi Hausse, Auburn University

The human body today has many replaceable parts, ranging from artificial hearts to myoelectric feet. What makes this possible is not just complicated technology and delicate surgical procedures. It's also an idea — that humans can and should alter patients' bodies in supremely difficult and invasive ways.


Where did that idea from?

Scholars often depict the American Civil War as an early watershed for amputation techniques and artificial limb design. Amputations were the most common operation of the war, and an entire prosthetics industry developed in response. Anyone who has seen a film or TV show has likely watched at least one scene of a surgeon grimly approaching a wounded soldier with saw in hand. Surgeons performed 60,000 amputations during the war, spending as little as three minutes per limb.

Yet, a momentous change in practices surrounding limb loss started much earlier – in 16th and 17th century Europe.

Illustration of mechanical iron hand, cross-sectioned to reveal the gears beneath the flesh

The surgeon Ambroise Paré printed a Parisian locksmith's design for a mechanical iron hand in the 16th century.

Instrumenta chyrurgiae et icones anathomicae/Ambroise Paré via Wellcome Collection


As a historian of early modern medicine, I explore how Western attitudes toward surgical and artisanal interventions in the body started transforming around 500 years ago. Europeans went from hesitating to perform amputations and few options for limb prostheses in 1500 to multiple amputation methods and complex iron hands for the affluent by 1700.

Amputation was seen as a last resort because of the high risk of . But some Europeans started to believe they could use it along with artificial limbs to shape the body. This break from a millennia-long tradition of noninvasive healing still influences modern biomedicine by giving physicians the idea that crossing the physical boundaries of the patient's body to drastically change it and embed technology into it could be a good thing. A modern hip replacement would be unthinkable without that underlying assumption.

Surgeons, gunpowder and the printing press

Early modern surgeons passionately debated where and how to cut the body to remove fingers, toes, arms and legs in ways medieval surgeons hadn't. This was partly because they confronted two new developments in the Renaissance: the spread of gunpowder warfare and the printing press.

Surgery was a craft learned through apprenticeship and years of traveling to train under different masters. Topical ointments and minor procedures like setting broken bones, lancing boils and stitching wounds filled surgeons' day-to-day practice. Because of their danger, major operations like amputations or trepanations – drilling a hole in the skull – were rare.


Widespread use of firearms and artillery strained traditional surgical practices by tearing bodies apart in ways that required immediate amputation. These weapons also created wounds susceptible to infection and gangrene by crushing tissue, disrupting blood flow and introducing debris — ranging from wood splinters and metal fragments to scraps of clothing — deep into the body. Mangled and gangrenous limbs forced surgeons to choose between performing invasive surgeries or letting their patients die.

The printing press gave surgeons grappling with these injuries a means to spread their ideas and techniques beyond the battlefield. The procedures they described in their treatises can sound gruesome, particularly because they operated without anesthetics, antibiotics, transfusions or standardized sterilization techniques.

Parchment sketch illustrating multiple types of hand amputations, including with a mallet and chisel

A 17th century treatise instructs surgeons to use a mallet and chisel among other amputation methods.

Johannes Scultetus/Universitätsbibliothek Heidelberg

But each method had an underlying rationale. Striking off a hand with a mallet and chisel made the amputation quick. Cutting through desensitized, dead flesh and burning away the remaining dead matter with a cautery iron prevented patients from bleeding to death.


While some wanted to save as much of the healthy body as possible, others insisted it was more important to reshape limbs so patients could use prostheses. Never before had European surgeons advocated amputation methods based on the placement and use of artificial limbs. Those who did so were coming to see the body not as something the surgeon should simply preserve, but rather as something the surgeon could mold.

Amputees, artisans and artificial limbs

As surgeons explored surgical intervention with saws, amputees experimented with making artificial limbs. Wooden peg devices, as they'd been for centuries, remained common lower limb prostheses. But creative collaborations with artisans were the driving force behind a new prosthetic technology that began appearing in the late 15th century: the mechanical iron hand.

Written sources reveal little about the experiences of most who survived limb amputation. Survival rates may have been as low as 25%. But among those who made it through, artifacts show improvisation was key to how they navigated their environments.

Photograph of an iron hand, the wrist to forearm composed of an open metal framework

A wearer operated this 16th century iron hand by pressing down on the fingers to lock them and pressing the release button at the top of the wrist to them.

Bonnevier, Helena, Livrustkammaren/SHM, CC BY-SA


This reflected a world in which prosthetics were not yet “medical.” In the U.S. today, a doctor's prescription is necessary for an artificial limb. Early modern surgeons sometimes provided small devices like artificial noses, but they didn't design, make or fit prosthetic limbs. Furthermore, there was no occupation comparable to today's prosthetists, or care professionals who make and fit prostheses. Instead, early modern amputees used their own resources and ingenuity to have ones made.

Iron hands were improvised creations. Their movable fingers locked into different positions through internal spring-driven mechanisms. They had lifelike details: engraved fingernails, wrinkles and even flesh-toned paint.

Wearers operated them by pressing down on the fingers to lock them into position and activating a release at the wrist to free them. In some iron hands the fingers move together, while in others they move individually. The most sophisticated are flexible in every joint of every finger.

Complex movement was more for impressing observers than everyday practicality. Iron hands were the Renaissance precursor to the “bionic-hand arms race” of today's prosthetics industry. More flashy and high-tech artificial hands – then and now – are also less affordable and user-friendly.


This technology drew from surprising places, including locks, clocks and luxury handguns. In a world without today's standardized models, early modern amputees commissioned prostheses from scratch by venturing into the craft market. As one 16th century contract between an amputee and a Genevan clockmaker attests, buyers dropped into the shops of artisans who'd never made a prosthesis to see what they could concoct.

Because these materials were often expensive, wearers tended to be wealthy. In fact, the introduction of iron hands marks the first time period when European scholars can readily distinguish between people of different social classes based on their prostheses.

Powerful ideas

Iron hands were important carriers of ideas. They prompted surgeons to think about prosthesis placement when they operated and created optimism about what humans could achieve with artificial limbs.


But scholars have missed how and why iron hands made this impact on medical culture because they've been too fixated on one kind of wearer – knights. Traditional assumptions that knights used iron hands to hold the reins of their horses offer only one narrow view of surviving artifacts.

A famous example colors this interpretation: the “second hand” of the 16th century German knight Götz von Berlichingen. In 1773, the playwright Goethe drew loosely from Götz's for a drama about a charismatic and fearless knight who dies tragically, wounded and imprisoned, while exclaiming “Freedom – freedom!”. (The historical Götz died of old age.)

Black and white photo of an iron hand clenched in a fist

A 19th century photograph of the famous ‘second hand' of Götz von Berlichingen with flexible finger joints.

Landesarchiv Baden-Württemberg/Wikimedia Commons., CC BY

Götz's story has inspired visions of a bionic warrior ever since. Whether in the 18th century or the 21st, you can find mythical depictions of Götz standing defiant in the face of authority and clutching a sword in his iron hand – an impractical feat for his historical prosthesis. Until recently, scholars supposed all iron hands must have belonged to knights like Götz.


But my research reveals that many iron hands show no signs of having belonged to warriors, or perhaps even to . Cultural pioneers, many of whom are known only from the artifacts they left behind, drew on stylish trends that prized clever mechanical devices, like the miniature clockwork galleon displayed today at the British . In a society that coveted ingenious objects blurring the boundaries between art and nature, amputees used iron hands to defy negative stereotypes depicting them as pitiable. Surgeons took note of these devices, praising them in their treatises. Iron hands spoke a material language contemporaries understood.

Before the modern body of replaceable parts could exist, the body had to be reimagined as something humans could mold. But this reimagining required the efforts of more than just surgeons. It also took the collaboration of amputees and the artisans who helped construct their new limbs.The Conversation

Heidi Hausse, Assistant Professor of History, Auburn University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Supermassive black holes have masses of more than a million suns – but their growth has slowed as the universe has aged



theconversation.com – Fan Zou, Graduate Student in Astronomy and Astrophysics, Penn – 2024-07-12 07:33:14
Most of the blue points in this sky survey image are accreting supermassive black holes emitting strong X-rays.
Fan Zou (Penn State) and the XMM-SERVS Collaboration

Fan Zou, Penn State and W. Niel Brandt, Penn State

Black holes are remarkable astronomical objects with gravity so strong that nothing, not even light, can escape them. The most gigantic ones, known as “supermassive” black holes, can weigh millions to billions times the mass of the Sun.

These giants usually live in the centers of galaxies. Our own galaxy, the Milky Way, contains a supermassive black hole in its heart as well.

So, how do these supermassive black holes become super massive? To answer this question, our team of astrophysicists looked back in time across the universe's 13.8 -year history to track how supermassive black holes have grown from the early days to .


We constructed a model of the overall growth history of supermassive black holes spanning the past 12 billion years.

How do supermassive black holes grow?

Supermassive black holes grow primarily in two ways. They can consume gas from their host galaxies in a process called accretion, and they can also merge with each other when two galaxies collide.

A black hole, shown as a dark dot in a swirling spiral of clouds.
An artist's illustration of an accreting supermassive black hole. The central black hole is black, while its surrounding gas heats up and shines to produce light.
Nahks Tr'Ehnl (Penn State)

When supermassive black holes consume gas, they almost always emit strong X-rays, a type of high-energy light invisible to the naked eye. You've probably heard of X-rays at the dentist, where they are sometimes used to examine your teeth. The X-rays used by astronomers generally have lower energies than medical X-rays.

So how can any light, even invisible X-rays, escape from black holes? Strictly speaking, the light is not coming from the black holes themselves, but from the gas just outside them. When gas gets pulled toward a black hole, it heats up and shines to produce light, like X-rays. The more gas a supermassive black hole consumes, the more X-rays it will produce.

Thanks to the data accumulated over more than 20 years from three of the most powerful X-ray facilities ever launched into Chandra, XMM-Newton and eROSITA – astronomers can capture X-rays from a large number of accreting supermassive black holes in the universe.


This data allows our research team to estimate how fast supermassive black holes grow by consuming gas. On average, a supermassive black hole can consume enough gas to amount to about the mass of the Sun each year, with the exact value depending upon various factors.

For example, the data shows that a black hole's growth rate, averaged over millions of years, is strongly connected to the mass of all the in its host galaxy.

How often do supermassive black holes merge?

Besides feeding on gas, supermassive black holes can also grow by merging with each other to form a single, more massive black hole when galaxies collide.

Supercomputer cosmological simulations can predict about how often these happen. These simulations aim to model how the universe grows and evolves over time. The countless galaxies flying through space are kind of like bricks, building up the universe.


These simulations show that galaxies and the supermassive black holes they host can undergo multiple mergers across the span of cosmic history.

Our team has tracked these two growth channels – gas consumption and mergers – using X-rays and supercomputer simulations, and then combined them to construct this overall growth history, which maps the growth of black holes across the universe over billions of years.

Our growth history revealed that supermassive black holes grew much faster billions of years ago, when the universe was younger.

Back in the early days, the universe contained more gas for supermassive black holes to consume, and supermassive black holes kept emerging. As the universe aged, the gas was gradually depleted, and supermassive black hole growth slowed. About 8 billion years ago, the number of supermassive black holes stabilized. It hasn't increased substantially since then.

Two small dark dots surrounded by gas clouds rotate near each other.
An illustration of a merger of two supermassive black holes.
Scott Noble (NASA GSFC)

When there isn't enough gas available for supermassive black holes to grow by accretion, the only way for them to get larger is through mergers. We didn't see very many cases of that in our growth history. On average, the most massive black holes can accumulate mass from mergers at a rate up to the mass of the Sun every several decades.

Looking forward

This research has helped us understand how over 90% of the mass in black holes has accumulated over the past 12 billion years.

However, we still need to investigate how they grew in the very early universe to explain the remaining few percentages of the mass in black holes. The astronomical community is starting to make progress exploring these early supermassive black holes, and we hope to find more answers soon.The Conversation

Fan Zou, Graduate Student in Astronomy and Astrophysics, Penn State and W. Niel Brandt, Professor of Astronomy and Astrophysics, Penn State

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Meteorites from Mars help scientists understand the red planet’s interior



theconversation.com – James Day, Professor of Geosciences, of California, San Diego – 2024-07-12 07:32:55
A Martian meteorite in cross-polarized light. This meteorite is dominated by the mineral olivine. Each grain is about half a millimeter across.
James Day

James Day, University of California, San Diego

Of the more than 74,000 known meteorites – rocks that fall to Earth from asteroids or planets colliding together – only 385 or so stones came from the planet Mars.

It's not that hard for scientists to work out that these meteorites from Mars. Various landers and rovers have been exploring Mars' surface for decades. Some of the early missions – the Viking landers – had the equipment to measure the composition of the planet's atmosphere. Scientists have shown that you can see this unique Martian atmospheric composition reflected in some of these meteorites.

Mars also has unique oxygen. Everything on Earth, humans and the we breathe, is made up of a specific composition of the three isotopes of the element oxygen: oxygen-16, oxygen-17 and oxygen-18. But Mars has an entirely different composition – it's like a geochemical fingerprint for being Martian.


The Martian meteorites found on Earth give geologists like me hints about the makeup of the red planet and its history of volcanic activity. They allow us to study Mars without sending a spacecraft 140 million miles away.

A planet of paradoxes

These Martian meteorites formed from once red-hot magma within Mars. Once these volcanic rocks cooled and crystallized, radioactive elements within them started to decay, acting as a radiometric clock that enables scientists to tell when they formed.

From these radiometric ages, we know that some Martian meteorites are as little as 175 million years old, which is – geologically speaking – quite young. Conversely, some of the Martian meteorites are older, and formed close to the time Mars itself formed.

These Martian meteorites tell a story of a planet that has been volcanically active throughout its entire history. In fact, there's potential for Martian volcanoes to erupt even , though scientists have never seen such an eruption.


The rocks themselves also preserve chemical information that indicates some of the major on Mars happened early in its history. Mars formed quite rapidly, 4.5 billion years ago, from gas and dust that made up the early solar system. Then, very soon after formation, its interior separated out into a metallic core and a solid rocky mantle and crust.

Since then, very little seems to have disturbed Mars' interior – unlike Earth, where plate tectonics has acted to stir and homogenize its deep interior. To use a food analogy, the Earth's interior is like a smoothie and Mars' is like a chunky fruit salad.

Two fume hoods with vials of sample under them.
Martian meteorite samples are prepared for analysis in a clean lab.
James Day

Martian volcano remnants

Understanding how Mars underwent such an early and violent adolescence, yet still may remain volcanically active today, is an area of great interest to me. I would like to know what the inside of Mars looks like, and how its interior makeup might explain features, like volcanoes, on the red planet's surface.

When geologists set out to answer questions about volcanism on Earth, we typically examine lava samples that erupted at different places or times from the same volcano. These samples allow us to disentangle local processes specific to each volcano from planetary processes that take place at a larger scale.

It turns out we can do the same thing for Mars. The rather exotically named nakhlite and chassignite meteorites are a group of rocks from Mars that erupted from the same volcanic system some 1.3 billion years ago.


Nakhlites are basaltic rocks, similar to lavas you would find in Iceland or Hawaii, with beautiful large crystals of a mineral known as clinopyroxene. Chassignites are rocks made almost entirely of the green mineral olivine – you might know the gem-quality variety of this mineral, peridot.

Along with the much more common shergottites, which are also basaltic rocks, and a few other more exotic Martian meteorite types, these categories of meteorite constitute all the rocks researchers possess from the red planet.

When studied together, nakhlites and chassignites tell researchers several things about Mars. First, as the molten rock that formed them oozed to the surface and eventually cooled and crystallized, some surrounding older rocks melted into them.

That older rock doesn't exist in our meteorite collection, so my team had to tease out its composition from the chemical information we obtained from nakhlites. From this information, we learned that the older rock was basaltic in composition and chemically distinct from other Martian meteorites. We found that it had been chemically weathered by exposure to and brine.


This older rock is quite different from the Martian crust samples in our meteorite collection today. In fact, it is much more like what we would expect the Martian crust to look like, based on data gathered by rover missions and satellites orbiting Mars.

We know that the magmas that made nakhlites and chassignites come from a distinct portion of Mars' mantle. The mantle is the rocky portion between Mars' crust and metallic core. These nakhlites and chassignites come from the solid rigid shell at the top of Mars' mantle, known as the mantle lithosphere, and this source makes them distinct from the more common shergottites.

Shergottites come from at least two sources within Mars. They may come from parts of the mantle just beneath the lithosphere, or even the deep mantle, which is closer to the planet's metallic core.

The interior structure of Mars, with the sources of meteorites indicated.
James Day

Understanding how volcanoes on Mars work can inform future research questions to be addressed by missions to the planet. It can also scientists understand whether the planet has ever been habitable for , or if it could be in the future.

Hints at habitability

Earth's active geological processes and volcanoes are part of what makes our planet habitable. The gases emanating from volcanoes are a major part of our atmosphere. So if Mars has similar geological processes, that could be good for the potential habitability of the red planet.


Mars is much smaller than Earth, however, and studies suggest that it's been losing the chemical elements essential for a sustainable atmosphere since it formed. It likely won't look anything like Earth in the future.

Our next steps for understanding Mars lie in learning how the basaltic shergottite meteorites formed. These are a diverse and richly complex set of rocks, ranging in age from 175 million years to 2.4 billion years or so.

Studying these meteorites in greater detail will help to prepare the next generation of scientists to analyze rocks collected using the Perseverance Rover for the forthcoming NASA Mars Sample Return mission.The Conversation

James Day, Professor of Geosciences, University of California, San Diego

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Storytelling strategies make communication about science more compelling



theconversation.com – Emma Frances Bloomfield, Associate Professor of Communication Studies, University of Nevada, Las Vegas – 2024-07-11 07:26:49
A story that includes characters and focuses on what people care about can stand up to misinformation.
SDI Productions/E+ via Getty Images

Emma Frances Bloomfield, University of Nevada, Las Vegas

As a science communication scholar, I've always supported vaccination and trusted medical experts – and I still do. As a new mom, however, I've been confronting new-to-me emotions and concerns while weighing decisions about my son's health.

Vaccines are incredibly effective and have minimal risks of side effects. But I began to see why some parents may hesitate because of the flood of content, especially online, about potential vaccine risks.

Part of what makes vaccine misinformation persuasive is its use of storytelling. Antivaccine advocates share powerful personal experiences of childhood illnesses or alleged vaccine side effects. It is rare, however, for scientists to use the same storytelling strategies to counter misinformation.


In my book “Science v. Story: Narrative Strategies for Science Communicators, I explore how to use stories to talk in a compelling way about controversial science topics, vaccination. To me, stories contain characters, action, sequence, scope, a storyteller, and content to varying degrees. By this definition, a story could be a book, a article, a social media post, or even a conversation with a friend.

While researching my book, I found that stories about science tend to be broad and abstract. On the other hand, science-skeptical stories tend to be specific and concrete. By borrowing some of the strategies of science-skeptical stories, I argue that evidence-backed stories about science can better compete with misinformation.

To make science's stories more concrete and engaging, it's important to put people in the story, explain science as a , and include what people care about.

woman and man with arms around each other looking at burned out house site
Stories hit home more when they include human characters and not just forces of nature.
VladTeodor/iStock via Getty Images Plus

Put people in the story

Science's stories often lack characters – at least, human ones. One easy way to make better stories is to include scientists making discoveries or performing experiments as the characters.

Characters can also be people affected by a scientific topic, or interested in learning more about it. For example, stories about climate change can include examples of people feeling the effects of more extreme weather events, such as the devastating impacts of California wildfires on local communities.


Characters can also be storytellers who are sharing their personal experiences. For example, I started this article with a brief discussion of my personal vaccine decisions. I was not a hidden or voiceless narrator, but someone sharing an experience that I hope others can relate to.

Explain science as a process

People often think of science as objective and unbiased. But science is actually a human practice that constantly involves choices, missteps and biases.

At the beginning of the pandemic, for example, the medical advice was not to mask. Scientists initially thought that masks didn't prevent transmission of the SARS-CoV-2 virus that causes COVID-19. However, after additional research, medical advice changed to masking, providing the public with the most updated and accurate knowledge.

If you explain science as a process, you can walk people through the sequence of how science is done and why researchers reach certain conclusions. Science communicators can emphasize how science is conducted and why people should trust the process of science to provide the most accurate conclusions possible given the available information.


Include what people care about

Scientific topics are important, but they may not always be the public's most pressing concerns. In April 2024, Gallup found that “the quality of the ” was one of the lowest-ranked priorities among people in the U.S. Of those polled, 37% said they cared a great deal about it. More immediate issues, such as (55%), and violence (53%), the (52%), and hunger and homelessness (52%) ranked much higher.

Stories about the environment could weave in connections to higher-priority topics to emphasize why the content is important. For example, stories can include information about how mitigating climate change can work hand in hand with improving the economy and creating jobs.

Medical provider faces woman and child, in discussion
A pediatrician is a science communicator, and so is a parent who talks about their own medical experiences.
SDI Productions/E+ via Getty Images

Telling science's stories

Scientists, of course, can be science communicators, but everyone can tell science's stories. When we share information online about health, or talk to friends and about the weather, we contribute to information that circulates about science topics.

My son's pediatrician was a science communicator when she explained the vaccine schedule and ways to keep my son comfortable after receiving vaccines. I was a science communicator when I spoke to others about my decisions to fully vaccinate my son on the recommended schedule, and how he is now a healthy and happy 9-month-old.

When communicating about science topics, remember to borrow features from stories to strengthen your message. Think about all of a story's features – character, action, sequence, scope, storyteller and content – and how you might incorporate them into the topic. Everyone can find opportunities to strengthen their science communication, whether it's in their jobs or in their everyday interactions with friends and family.The Conversation

Emma Frances Bloomfield, Associate Professor of Communication Studies, University of Nevada, Las Vegas


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