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Bacteria can develop resistance to drugs they haven’t encountered before − scientists figured this out decades ago in a classic experiment

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Bacteria can develop resistance to drugs they haven’t encountered before − scientists figured this out decades ago in a classic experiment

Bacteria are evolutionarily primed to outpace drug developers.
National Institute of Allergy and Infectious Diseases, National Institutes of Health/Flickr, CC BY-NC

Qi Zheng, Texas A&M University

Do bacteria mutate randomly, or do they mutate for a purpose? Researchers have been puzzling over this conundrum for over a century.

In 1943, microbiologist Salvador Luria and physicist turned biologist Max Delbrück invented an experiment to argue that bacteria mutated aimlessly. Using their test, other scientists showed that bacteria could acquire resistance to antibiotics they hadn’t encountered before.

The Luria–Delbrück experiment has had a significant effect on science. The findings helped Luria and Delbruck win the Nobel Prize in physiology or medicine in 1969, and students today learn this experiment in biology classrooms. I have been studying this experiment in my work as a biostatistician for over 20 years.


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Decades later, this experiment offers lessons still relevant today, because it implies that bacteria can develop resistance to antibiotics that haven’t been developed yet.

Slot machines and a eureka moment

Imagine a test tube containing bacteria living in nutrient broth. The broth is cloudy due to the high concentration of bacteria within it. Adding a virus that infects bacteria, also known as a phage, into the tube kills most of the bacteria and makes the broth clear.

Illustration of bacteriophage structure.
Bacteriophages are viruses that specifically infect bacteria.
Kristina Dukart/iStock via Getty Images Plus

However, keeping the test tube under conditions favorable for bacterial growth will turn the broth cloudy again over time. This indicates that the bacteria developed resistance against the phages and were able to proliferate.

What role did the phages play in this change?

Some scientists thought the phages incited the bacteria to mutate for survival. Others suggested that bacteria routinely mutate randomly, and the development of phage-resistant variants was simply a lucky outcome. Luria and Delbrück had been working together for months to solve this conundrum, but none of their experiments had been successful.

On the night of Jan. 16, 1943, Luria got a hint about how to crack the mystery while watching a colleague hit the jackpot at a slot machine. The next morning, he hurried to his lab.

Luria’s experiment consisted of a few tubes and dishes. Each tube contained nutrient broth that would help the bacteria E. coli multiply, while each dish contained material coated with phages. A few bacteria were placed into each tube and given two opportunities to generate phage-resistant variants. They could either mutate in the tubes in the absence of phages, or they could mutate in the dishes in the presence of phages.

Illustration of six test tubes and and six petri dishes, a few of the dishes containing red dots
This diagram of the Luria-Delbrück experiment depicts colonies of phage-resistant variants of E. coli (red) developing in petri dishes.
Qi Zheng, CC BY-SA

The next day, Luria transferred the bacteria in each tube into a dish filled with phages. The day after that, he counted the number of resistant bacterial colonies in each dish.

If bacteria develop resistance against phages by interacting with them, none of the bacteria in the tubes should have mutations. On the other hand, only a few of the bacteria – say, 1 out of 10 million bacteria – should spawn resistant variants when they are transferred into a dish containing phages. Each phage-resistant variant would grow into a colony, but the remaining bacteria would die from infection.

If bacteria develop resistance independently of interacting with phages, some of the bacteria in the tubes will have mutations. This is because each time a bacterium divides in a tube, it has a small probability of spawning a resistant variant. If the starting generation of bacteria is the first to mutate, at least half of the bacteria will be resistant in later generations. If a bacterium in the second generation is the first to mutate, at lest an eighth of the bacteria will be resistant in later generations.

Four tree diagrams of green and red circles, with subsequent branches from red dots turning red
Mutations that confer resistance against phages (red) early on will spawn a large number of phage-resistant variants, while mutations that occur later on will spawn only a few resistant variants.
Qi Zheng, CC BY-SA

Like small-prize cash-outs in slot machines, late-generation mutations occur more often but give fewer resistant variants. Like jackpots, early-generation mutations occur rarely but give large numbers of variants. Early-generation mutations are rare because early on there are only a small number of bacteria available to mutate.

For example, in a 20-generation experiment, a mutation occurring at the 10th generation of bacteria would give 1,024 phage-resistant variants. A mutation occurring at the 17th generation would give only four phage-resistant variants.

The number of resistant colonies in Luria’s experiments showed a similar pattern to that of slot machine cash-outs. Most dishes contained no or small numbers of mutant colonies, but several contained a large number of mutant colonies that Luria considered jackpots. This meant that the bacteria developed resistant variants before they interacted with the phages in the dishes.

An experiment’s legacy

Luria sent a note to Delbrück after his experiment was completed, asking him to check his work. The two scientists then worked together to write a classic paper describing the experimental protocol and a theoretical framework to measure bacterial mutation rates.

Other scientists conducted similar experiments by replacing phages with penicillin and with tuberculosis drugs. Similarly, they found that bacteria did not need to encounter an antibiotic to acquire resistance to it.

Bacteria have relied on random mutations to cope with harsh, constantly changing environments for millions of years. Their incessant, random mutations will lead them to inevitably develop variants that are resistant to the antibiotics of the future.

Drug resistance is a reality of life we will have to accept and continue to fight against.The Conversation

Qi Zheng, Professor of Biostatistics, Texas A&M University

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

The Conversation

Understanding paranormal beliefs and conspiracy theories isn’t just about misinformation – this course unpacks the history

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theconversation.com – Jeb Card, Associate Teaching Professor of Anthropology, Miami University – 2025-01-27 07:50:00

Understanding paranormal beliefs and conspiracy theories isn’t just about misinformation – this course unpacks the history

The ‘black mailbox’ along Highway 375 near Rachel, Nev., a traditional spot for UFO hunters to meet and search the skies near Area 51.
AP Photo/John Locher

Jeb Card, Miami University

Uncommon Courses is an occasional series from The Conversation U.S. highlighting unconventional approaches to teaching.

Title of course:

“Investigating the Paranormal”

What prompted the idea for the course?

My training and professional work have been in Mesoamerican archaeology, but I’ve had a lifelong fascination with paranormal concepts. In fact, I considered studying the UFO community for my doctoral research in cultural anthropology.

I eventually fused these two interests in my book “Spooky Archaeology: Myth and the Science of the Past,” which examines why archaeology shows up so much in ideas about the mysterious and weird. Most people are familiar with pop culture characters like Indiana Jones seeking magical artifacts. Perhaps less immediately obvious is just how common archaeological topics are in paranormal and conspiracy culture.

The popularity of paranormal ideas – from television shows and thousands of podcasts to UFOs on the front page of The New York Times and in government investigations – made it clear that a course on paranormal culture would be an excellent way for students to get a taste of social science research.

What does the course explore?

The material begins with premodern ideas of magic, myth and metaphysics. The narrative that “Western” societies tell of the development of the modern world is that the Enlightenment cast off supernatural thinking in favor of science. The historical reality, however, is not so simple.

As science based on observation of material evidence emerged in the 17th through 19th centuries, so did a paranormal worldview: theories about a nonmaterial or hidden reality beyond the mundane, from monsters to psychic powers. Some of these ideas were tied to older religious notions of the sacred or strange but not divine phenomena. Others were new – particularly those suggesting the hidden existence of prehistoric extinct creatures or lost cities.

In either case, the key element was that proponents of these ideas often tried to support their existence with the kind of evidence used in science, though their “proofs” fell short of scientific standards. In other words, the paranormal is in conflict with the knowledge and worldview of modernity but also attempts to use the concepts of modernity to oppose it.

The class examines how this tension produced 20th century “-ologies” like parapsychology, which examines evidence for consciousness beyond matter, and cryptozoology, which searches the ends of the Earth for creatures tied to the mythic past. We also learn about UFOlogy, whose proponents have collected alleged contacts with technology and beings from beyond this world ever since the Cold War, as great earthly powers filled the skies with secretive hi-tech aircraft and spaceships.

As the class concludes, we examine how the “-ologies” declined after the Cold War, alongside the cultural capital of science, whose height of public respect was in the mid-20th century. Since then, proving the existence of paranormal things to institutional scientists has become less important in paranormal communities than promoting them to a broader public.

Why is this course relevant now?

Beyond public interest in paranormal topics, the paranormal is entwined with sociocultural forces that have dramatically increased the role of conspiracy rhetoric in the United States and elsewhere. At their core, both types of belief claim to have figured out some kind of supposedly hidden knowledge.

Furthermore, the conspiracy theories that are now commonplace in American political discourse are more rooted in paranormal ideas than in previous decades. Conspiracy theories about the JFK assassination or even 9/11 were still largely within the materialist realm. People argued that “the truth” had been covered up, but their arguments did not rely on metaphysical ideas. Today, major conspiracy theories involve secret cabals, mystical symbols and code words, demonic forces and extraterrestrial entities.

What’s a critical lesson from the course?

Evidence must be interrogated on its own, regardless of whether it fits your perspective. I find time and again that students have a hard time approaching evidence without bias, whether that bias is conscious or not: “knowing” that something must be true, or must be absurd.

One person apparently makes a death bed confession of faking a famous Loch Ness Monster photo, pleasing skeptics. Another claims to have seen a Bigfoot at close range, pleasing believers. Without further evidence, both are stories: no more, no less.

The issue isn’t to draw an equivalence between the bigger concepts. Not all narratives are equally well-founded. But students learn how to collect evidence, rather than simply rely on their gut sense of what is plausible or not.

What will the course prepare students to do?

This course is meant to help students discern useful and reliable information about claims and events, separating them from irrelevant or inaccurate narratives or sources. The goal is not just “critical thinking” aimed at combating disinformation, though that is part of what they should learn. Students practice evaluating evidence but also develop an approach for analyzing and understanding phenomena behind it: how factors like history, culture and institutions of authority, such as science and government, shape what people trust and what they believe.The Conversation

Jeb Card, Associate Teaching Professor of Anthropology, Miami University

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

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Can Trump just order new names for Denali and the Gulf of Mexico? A geographer explains who decides what goes on the map

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theconversation.com – Innisfree McKinnon, Associate Professor of Geography, University of Wisconsin-Stout – 2025-01-24 15:02:00

Known as Mount McKinley until 2015, Denali’s current name reflects what Native Alaskans call the mountain.
Arterra/Universal Images Group via Getty Images

Innisfree McKinnon, University of Wisconsin-Stout

President Donald Trump’s executive order to rename the Gulf of Mexico and Alaska’s Denali, the tallest peak in the country, has resulted in lots of discussion. While for some, such renaming might seem less important than the big problems the country faces, there is a formal process in the United States for renaming places, and that process is taken seriously.

Usually, so people don’t get confused, official, agreed-upon names are used by the government. In the U.S., place names are standardized by the U.S. Board on Geographic Names, which is part of the U.S. Geological Survey, the agency in charge of making maps.

In his executive order, Trump asks the Board on Geographic Names “to honor the contributions of visionary and patriotic Americans” and change its policies and procedures to reflect that.

Usually, renaming a place starts locally. The people in the state or county propose a name change and gather support. The process in each state is different.

A lake with sailboats and a city skyline in the background
Lake Bde Maka Ska, formerly Lake Calhoun, is the largest lake in Minneapolis.
YinYang/E+ via Getty

How to change a place name

Minnesota recently changed the name of a large lake in Minneapolis to Bde Maka Ska, which the Minneapolis Park Board described as “a Dakota name for the lake that has been passed down in oral history for many years.”

The board voted to change the name and took its request to the county commissioners. When the county agreed, the request was then sent to the Minnesota Department of Natural Resources, which made it official for Minnesota. Then, the state of Minnesota sent the request to the Board on Geographic Names, which made it official for the entire U.S.

It’s a lot of paperwork for something so seemingly minor, but people get passionate about place names. It took 40 years to rename Denali from the name established in the late 19th century, Mount McKinley.

The state of Alaska requested the name change in 1975, but the Board on Geographic Names didn’t take action. Members of the Ohio congressional delegation – President William McKinley was from Ohio – objected over many years to requests to rename the mountain, and the board did not act on those requests.

The president appoints the secretary of the Interior Department. The secretary works with the heads of related agencies to appoint the Board on Geographic Names. Current committee policy states, “Input from State geographic names authorities, land
management agencies, local governments, and Tribal Governments
are actively pursued.”

In 2015, President Barack Obama named a new leader for the Department of the Interior, Sally Jewell. Just as Obama made a trip to Alaska in late August 2015, Jewell declared the name change official under a law that allows the secretary of the Interior to change a name if the board doesn’t act on the proposal in a “reasonable” amount of time.

“This name change recognizes the sacred status of Denali to many Alaska Natives,” Jewell said. “The name Denali has been official for use by the State of Alaska since 1975, but even more importantly, the mountain has been known as Denali for generations. With our own sense of reverence for this place, we are officially renaming the mountain Denali in recognition of the traditions of Alaska Natives and the strong support of the people of Alaska.”

If someone objects to a name change, they could ask the courts to rule on whether the name change was made legally. Going back to Bde Maka Ska, some people objected to changing the name from Lake Calhoun, so they took the state natural resources agency to court. Eventually, the Minnesota Supreme Court ruled that the name change was done correctly.

Alaska’s two U.S. senators and prominent state figures have strongly objected to Trump’s renaming attempt.

How not to change a place name

Renaming the Gulf of Mexico is a different kind of case, however, from renaming a geographic place within U.S. borders.

The gulf is not within the territorial U.S. On the coast, the first 12 miles from shore are considered part of that country, but outside of that is international waters.

The Board on Geographic Names could change the name to Gulf of America on official U.S. maps, but there is no international board in charge of place names. Each country decides what to call places. And there is no official way for the U.S. to make other countries change the name.

It’s possible that the U.S. could formally ask other countries to change the name, or even impose sanctions against countries that don’t comply.

If the names were officially changed in the U.S., the government would use the new names in official documents, signage and maps. As for all the people and companies in the world that make maps, they usually use the official names. But there is nothing that would force them to, if they believed that a certain name is more widely recognized.The Conversation

Innisfree McKinnon, Associate Professor of Geography, University of Wisconsin-Stout

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

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Trump inherits the Guantánamo prison, complete with 4 ‘forever prisoners’

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theconversation.com – Lisa Hajjar, Professor of Sociology, University of California, Santa Barbara – 2025-01-24 10:57:00

A control tower overlooks the Camp VI detention facility, at Guantánamo Bay Naval Base, Cuba.
AP Photo/Alex Brandon

Lisa Hajjar, University of California, Santa Barbara

President Joe Biden’s record of handling the U.S. military prison at Guantánamo Bay, Cuba, is decidedly mixed. He succeeded in reducing the detainee population he inherited by more than half, but he compounded problems in the military commissions that the Bush administration had invented in the wake of the 9/11 attacks to try people captured in the “war on terror.” Now all the problems at Guantánamo are again President Donald Trump’s.

When Biden took office in 2021, there were 40 prisoners. Today there are 15, the lowest number since the first 20 Muslim men and boys captured in Afghanistan were airlifted to the base on Jan. 11, 2002.

Biden left Trump four people the U.S. will not release but also cannot put on trial – the so-called “forever prisoners.” He also left intact the troubled military commissions system, with three pending criminal cases against a total of six detainees.

In December 2021, former chief military defense attorney Brig. Gen. John Baker testified before the Senate Judiciary Committee: “It is too late in the process for the current military commissions to do justice for anyone. The best that can be hoped for at this point … is to bring this sordid chapter of American history to an end.” Baker made clear that the only viable option is to resolve the cases with plea bargains for the defendants.

Marine Brig. Gen. John Baker tells U.S. senators that there is no opportunity for justice to be done at Guantánamo.

A chance to make progress

There are three cases that have not yet gone to trial – the 9/11 case with four defendants facing charges for their connections with the attacks, the USS Cole bombing in October 2000 with one defendant and the Bali bombing in October 2002 with one defendant.

The 9/11 and USS Cole cases have been stuck in the pretrial phase since Biden was Barack Obama’s vice president. In the summer of 2024, a breakthrough in the 9/11 case appeared imminent: Prosecutors and defense lawyers for three of the four defendants reportedly reached plea-bargain agreements. Khalid Sheikh Mohammad – the alleged “mastermind” of the attacks – Walid bin Attash and Mustafa Hawsawi agreed to plead guilty and accept life sentences in exchange for the government taking the death penalty off the table. There was no deal for the fourth 9/11 defendant, Ammar al-Baluchi.

The deals were approved on July 31 by the top military officer overseeing the Guantánamo commissions, retired Brig. Gen. Susan Escallier. But two days later, Biden’s defense secretary, Lloyd Austin, stepped into the process and overrode Escallier – whom he had appointed. Austin announced that the plea deals were revoked.

The judge, Air Force Col. Matthew McCall, decided to schedule plea hearings for early January. But after some legal back-and-forth that forced a stay, he had to cancel them. Biden left the case against three 9/11 defendants in limbo.

A beige one-story building with a sign above the door.
The basement of this government building in Bucharest, Romania, held a secret CIA prison, one of many across the world.
AP Photo

Witness to the transition

In mid-January 2025, I made my sixteenth reporting trip to Guantánamo. I came for closing arguments on a motion in the 9/11 case that seeks to suppress statements that Ammar al-Baluchi made to the FBI in January 2007. That was four months after he and 13 others were transferred to Guantánamo from CIA black sites where they were held for years. The litigation to suppress those statements started in 2019.

In Chapter 10 of my book, “The War in Court: Inside the Long Fight against Torture,” I detail how the litigation on this suppression motion made public previously unknown details and under-acknowledged horrors of the CIA’s rendition, detention and interrogation program.

These closing arguments were the culmination of six years of litigation on the key question in the 9/11 case: Does torture matter in the pursuit of justice in the military commissions?

A figure strapped to a table has water poured on its face.
A drawing by Guantánamo detainee Abu Zubaydah depicts a person being waterboarded.
Copyright Abu Zubaydah 2019. Licensed by Professor Mark Denbeaux, Seton Hall Law School

Can Guantánamo be closed?

Of the 780 people ever detained at Guantánamo, 540 were released during the presidency of George W. Bush, who established the detention facility. Obama, who signed an executive order on his second day in office pledging to close Guantánamo within a year, released 200.

In his first term, Trump pledged to keep the facility open. The only man to leave Guantánamo during Trump’s first term was Ahmed al-Darbi, who was repatriated to Saudi Arabia in 2018 to serve out the remainder of his sentence from a 2014 plea bargain agreement.

When Biden took office, he said that he supported shutting down the military prison at Guantánamo. In the early years of his presidency, there was a slow stream of transfers, mostly people who had been cleared for release long ago and were freed.

In Biden’s last months, the pace of transfers quickened. In December 2024, a Kenyan detainee, two Malaysian members of al-Qaida who had pled guilty the previous January, and a Tunisian man who had been in Guantánamo since the day the facility was opened were all repatriated to their countries of origin and freed. In January 2024, 11 Yemenis were transported from the prison to Oman to be resettled.

15 men left behind

The Biden administration had also planned to repatriate a severely disabled Iraqi detainee, Abd al-Hadi al-Iraqi, to serve out his plea-bargained sentence in a Baghdad prison. But a federal judge blocked that transfer, ruling that al-Iraqi would not get necessary medical treatment in Iraq and might be subject to abuse there.

Al-Iraqi is one of the 15 that Biden left behind. Three of them – a Libyan, a Somali and a stateless Rohingya – have long been cleared for release. Their continuing detention without charges highlights a key element of the Guantánamo problem: No one can be released unless the U.S. government finds another country willing to accept them.

One of the remaining detainees, Ali Bahlul, is serving a life sentence for conspiracy to commit war crimes. Six others, including the four 9/11 defendants, are awaiting their trials.

There are also four detainees whom the government refuses to transfer but cannot put on trial for lack of evidence.

A man wearing a beard, mustache and glasses.
The U.S. goverment says it cannot release Abu Zubaydah from Guantánamo because he would disclose classified interrogation techniques critics have labeled torture.
U.S. Central Command via AP

These so-called “forever prisoners” include Abu Zubaydah, a Saudi-born man of Palestinian descent who was taken into CIA custody in 2002 and was used as the guinea pig for the CIA torture program. The government long ago conceded that Abu Zubaydah was not a top leader of al-Qaida – in fact he was not even a member. But he will not be released because he knows how he was treated by the CIA, and that treatment remains highly classified.

The newest forever prisoner is one of the original 9/11 defendants, Ramzi bin al-Shibh; in September 2023, he was declared mentally incompetent to stand trial. Now he is uncharged, unreleased and untreated for his psychological maladies that were caused by the torture he endured in CIA black sites.

The ‘War on Terror’ is not over

When Biden pulled U.S. troops out of Afghanistan in August 2021, he claimed to have ended America’s longest war – and repeated this claim in a January 2025 speech. But the Guantánamo prison remains open, and as long as it is, the “war on terror,” which first put U.S. troops in Afghanistan in 2001, is not over.

How Trump will deal with Guantánamo is an open question. If he focuses on the death penalty, he will press ahead with military commission trials like his predecessors, hoping for unanimous guilty verdicts and death sentences. If he prioritizes cutting wasteful government spending, he will release additional detainees and allow the three plea bargain agreements to go into effect.

No one I spoke to during my last trip was willing to predict what a second Trump term might bode for Guantánamo – except that it won’t be closed.The Conversation

Lisa Hajjar, Professor of Sociology, University of California, Santa Barbara

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

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