Giving University Exams in the Age of Chatbots

What I like most about teaching "Open Source Strategies" at École Polytechnique de Louvain is how much I learn from my students, especially during the exam.

I dislike exams. I still have nightmares about exams. That’s why I try to subvert this stressful moment and make it a learning opportunity. I know that adrenaline increases memorization dramatically. I make sure to explain to each student what I was expecting and to be helpful.

Here are the rules:

1. You can have all the resources you want (including a laptop connected to the Internet)
2. There’s no formal time limit (but if you stay too long, it’s a symptom of a deeper problem)
3. I allow students to discuss among themselves if it is on topic. (in reality, they never do it spontanously until I force two students with a similar problem to discuss together)
4. You can prepare and bring your own exam question if you want (something done by fewer than 10% of the students)
5. Come dressed for the exam you dream of taking!

This last rule is awesome. Over the years, I have had a lot of fun with traditional folkloric clothing from different countries, students in pajamas, a banana and this year’s champion, my Studentausorus Rex!

My all-time favourite is still a fully clothed Minnie Mouse, who did an awesome exam with full face make-up, big ears, big shoes, and huge gloves. I still regret not taking a picture, but she was the very first student to take my words for what was a joke and started a tradition over the years.

Giving Chatbots Choice to the Students

Rule N°1 implies having all the resources you want. But what about chatbots? I didn’t want to test how ChatGPT was answering my questions, I wanted to help my students better understand what Open Source means.

Before the exam, I copy/pasted my questions into some LLMs and, yes, the results were interesting enough. So I came up with the following solution: I would let the students choose whether they wanted to use an LLM or not. This was an experiment.

The questionnaire contained the following:

# Use of Chatbots

Tell the professor if you usually use chatbots (ChatGPT/LLM/whatever) when doing research and investigating a subject. You have the choice to use them or not during the exam, but you must decide in advance and inform the professor.

Option A: I will not use any chatbot, only traditional web searches. Any use of them will be considered cheating.

Option B: I may use a chatbot as it’s part of my toolbox. I will then respect the following rules:
1) I will inform the professor each time information come from a chatbot
2) When explaining my answers, I will share the prompts I’ve used so the professor understands how I use the tool
3) I will identify mistakes in answers from the chatbot and explain why those are mistakes

Not following those rules will be considered cheating. Mistakes made by chatbots will be considered more important than honest human mistakes, resulting in the loss of more points. If you use chatbots, you should be held accountable for the output.

I thought this was fair. You can use chatbots, but you will be held accountable for it.

Most Students Don’t Want to Use Chatbots

This January, I saw 60 students. I interacted with each of them for a mean time of 26 minutes. This is a tiring but really rewarding process.

Of 60 students, 57 decided not to use any chatbots. For 30 of them, I managed to ask them to explain their choices. For the others, I unfortunately did not have the time. After the exam, I grouped those justifications into four different clusters. I did it without looking at their grades.

The first group is the "personal preference" group. They prefer not to use chatbots. They use them only as a last resort, in very special cases or for very specific subjects. Some even made it a matter of personal pride. Two students told me explicitly "For this course, I want to be proud of myself." Another also explained: "If I need to verify what an LLM said, it will take more time!"

The second group was the "never use" one. They don’t use LLMs at all. Some are even very angry at them, not for philosophical reasons, but mainly because they hate the interactions. One student told me: "Can I summarize this for you? No, shut up! I can read it by myself you stupid bot."

The third group was the "pragmatic" group. They reasoned that this was the kind of exam where it would not be needed.

The last and fourth group was the "heavy user" group. They told me they heavily use chatbots but, in this case, were afraid of the constraints. They were afraid of having to justify a chatbot’s output or of missing a mistake.

After doing that clustering, I wrote the grade of each student in its own cluster and I was shocked by how coherent it was. Note: grades are between 0 and 20, with 10 being the minimum grade to pass the class.

The "personal preference" students were all between 15 and 19, which makes them very good students, without exception! The "proud" students were all above 17!

The "never use" was composed of middle-ground students around 13 with one outlier below 10.

The pragmatics were in the same vein but a bit better: they were all between 12 and 16 without exceptions.

The heavy users were, by far, the worst. All students were between 8 and 11, with only one exception at 16.

This is, of course, not an unbiased scientific experiment. I didn’t expect anything. I will not make any conclusion. I only share the observation.

But Some Do

Of 60 students, only 3 decided to use chatbots. This is not very representative, but I still learned a lot because part of the constraints was to show me how they used chatbots. I hoped to learn more about their process.

The first chatbot student forgot to use it. He did the whole exam and then, at the end, told me he hadn’t thought about using chatbots. I guess this put him in the "pragmatic" group.

The second chatbot student asked only a couple of short questions to make sure he clearly understood some concepts. This was a smart and minimal use of LLMs. The resulting exam was good. I’m sure he could have done it without a chatbot. The questions he asked were mostly a matter of improving his confidence in his own reasoning.

This reminded me of a previous-year student who told me he used chatbots to study. When I asked how, he told me he would tell the chatbot to act as the professor and ask exam questions. As a student, this allowed him to know whether he understood enough. I found the idea smart but not groundbreaking (my generation simply used previous years’ questions).

The third chatbot-using student had a very complex setup where he would use one LLM, then ask another unrelated LLM for confirmation. He had walls of text that were barely readable. When glancing at his screen, I immediately spotted a mistake (a chatbot explaining that "Sepia Search is a compass for the whole Fediverse"). I asked if he understood the problem with that specific sentence. He did not. Then I asked him questions for which I had seen the solution printed in his LLM output. He could not answer even though he had the answer on his screen.

But once we began a chatbot-less discussion, I discovered that his understanding of the whole matter was okay-ish. So, in this case, chatbots disserved him heavily. He was totally lost in his own setup. He had LLMs generate walls of text he could not read. Instead of trying to think for himself, he tried to have chatbots pass the exam for him, which was doomed to fail because I was asking him, not the chatbots. He passed but would probably have fared better without chatbots.

Can chatbots help? Yes, if you know how to use them. But if you do, chances are you don’t need chatbots.

A Generational Fear of Cheating

One clear conclusion is that the vast majority of students do not trust chatbots. If they are explicitly made accountable for what a chatbot says, they immediately choose not to use it at all.

One obvious bias is that students want to please the teacher, and I guess they know where I am on this spectrum. One even told me: "I think you do not like chatbots very much so I will pass the exam without them" (very pragmatic of him).

But I also minimized one important generational bias: the fear of cheating. When I was a student, being caught cheating was a clear zero for the exam. You could, in theory, be expelled from university for aggravated cheating, whatever "aggravated" could mean.

During the exam, a good number of students called me panicked because Google was forcing autogenerated answers and they could not disable it. They were very worried I would consider this cheating.

First, I realized that, like GitHub, Google has a 100% market share, to the point students don’t even consider using something else a possibility. I should work on that next year.

Second, I learned that cheating, however lightly, is now considered a major crime. It might result in the student being banned from any university in the country for three years. Discussing exam with someone who has yet to pass it might be considered cheating. Students have very strict rules on their Discord.

I was completely flabbergasted because, to me, discussing "What questions did you have?" was always part of the collaboration between students. I remember one specific exam where we gathered in an empty room and we helped each other before passing it. When one would finish her exam, she would come back to the room and tell all the remaining students what questions she had and how she solved them. We never considered that "cheating" and, as a professor, I always design my exams hoping that the good one (who usually choose to pass the exam early) will help the remaining crowd. Every learning opportunity is good to take!

I realized that my students are so afraid of cheating that they mostly don’t collaborate before their exams! At least not as much as what we were doing.

In retrospect, my instructions were probably too harsh and discouraged some students from using chatbots.

Stream of Consciousness

Another innovation I introduced in the 2026 exam was the stream of consciousness. I asked them to open an empty text file and keep a stream of consciousness during the exam. The rules were the following:

In this file, please write all your questions and all your answers as a "stream of consciousness." This means the following rules:

1. Don’t delete anything.
2. Don’t correct anything.
3. Never go backward to retouch anything.
4. Write as thoughts come.
5. No copy/pasting allowed (only exception: URLs)
6. Rule 5. implies no chatbot for this exercice. This is your own stream of consciousness.

Don’t worry, you won’t be judged on that file. This is a tool to help you during the exam. You can swear, you can write wrong things. Just keep writing without deleting. If you are lost, write why you are lost. Be honest with yourself.

This file will only be used to try to get you more points, but only if it is clear that the rules have been followed.

I asked them to send me the file within 24h after the exam. Out of 60 students, I received 55 files (the remaining 5 were not penalized). There was also a bonus point if you sent it to the exam git repository using git-send-email, something 24 managed to do correctly.

The results were incredible. I did not read them all but this tool allowed me to have a glimpse inside the minds of the students. One said: "I should have used AI, this is the kind of question perfect for AI" (he did very well without it). For others, I realized how much stress they had but were hiding. I was touched by one stream of consciousness starting with "I’m stressed, this doesn’t make any sense. Why can’t we correct what we write in this file" then, 15 lines later "this is funny how writing the questions with my own words made the problem much clearer and how the stress start to fade away".

And yes, I read all the failed students and managed to save a bunch of them when it was clear that they, in fact, understood the matter but could not articulate it well in front of me because of the stress. Unfortunately, not everybody could be saved.

Conclusion

My main takeaway is that I will keep this method next year. I believe that students are confronted with their own use of chatbots. I also learn how they use them. I’m delighted to read their thought processes through the stream of consciousness.

Like every generation of students, there are good students, bad students and very brilliant students. It will always be the case, people evolve (I was, myself, not a very good student). Chatbots don’t change anything regarding that. Like every new technology, smart young people are very critical and, by defintion, smart about how they use it.

The problem is not the young generation. The problem is the older generation destroying critical infrastructure out of fear of missing out on the new shiny thing from big corp’s marketing department.

Most of my students don’t like email. An awful lot of them learned only with me that Git is not the GitHub command-line tool. It turns out that by imposing Outlook with mandatory subscription to useless academic emails, we make sure that students hate email (Microsoft is on a mission to destroy email with the worst possible user experience).

I will never forgive the people who decided to migrate university mail servers to Outlook. This was both incompetence and malice on a terrifying level because there were enough warnings and opposition from very competent people at the time. Yet they decided to destroy one of the university’s core infrastructures and historical foundations (UCLouvain is listed by Peter Salus as the very first European university to have a mail server, there were famous pioneers in the department).

By using Outlook, they continue to destroy the email experience. Out of 55 streams of consciousness, 15 ended in my spam folder. All had their links destroyed by Outlook. And university keep sending so many useless emails to everyone. One of my students told me that they refer to their university email as "La boîte à spams du recteur" (Chancellor’s spam inbox). And I dare to ask why they use Discord?

Another student asked me why it took four years of computer engineering studies to get a teacher explaining to them that Git was not GitHub and that GitHub was part of Microsoft. He had a distressed look: "How could I have known? We were imposed GitHub for so many exercises!"

• How GitHub monopoly is destroying the open source ecosystem (ploum.net)

Each year, I tell my students the following:

It took me 20 years after university to learn what I know today about computers. And I’ve only one reason to be there in front of you: be sure you are faster than me. Be sure that you do it better and deeper than I did. If you don’t manage to outsmart me, I will have failed.

Because that’s what progress is about. Progress is each generation going further than the previous one while learning from the mistakes of olders. I’m there to tell you about my own mistakes and the mistakes of my generation.

I know that most of you are only there to get a diploma while doing the minimal required effort. Fair enough, that’s part of the game. Challenge accepted. I will try to make you think even if you don’t intend to do it.

In earnest, I have a lot of fun teaching, even during the exam. For my students, the mileage may vary. But for the second time in my life, a student gave me the best possible compliment:

— You know, you are the only course for which I wake up at 8AM.

To which I responded:

– This is reciprocal. I hate waking up early, except to teach in front of you.

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Good morning, and welcome to Vittles! Today’s essay is a long read by Joe Zadeh about the persistent fears in the West surrounding the reheating of rice. It’s the first piece that we’re publishing online from our second print issue, on the theme of ‘Bad Food’. The magazine contains lots of other deeply researched and engaging pieces about contemporary food culture – specifically the messy, unglamorous and chaotic aspects of it. You should buy a copy.

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‘What are you talking about?’ Dad asked me, a look of incredulity on his face. ‘I’ve been reheating rice all my life.’ It was a warm Saturday evening. We were sitting at the dining table in his home in Gateshead, drinking beer and eating from a plastic tub of M&S bell peppers stuffed with ricotta. I had just told him that I was researching a story about the dangers of reheated rice – more specifically, the illness that has come to be dubbed ‘fried rice syndrome’ or ‘reheated rice syndrome’ across the Western world. Search those terms on most platforms, and you’ll find hugely popular posts issuing dire warnings about the condition. ‘Hospital workers say it’s some of the worst cases of food poisoning they’ve ever seen. And it can lead to death,’ reported food52, in a TikTok post with more than 431,000 likes at the time of writing.

Dad didn’t take this news well. He got up from the table, marched to the fridge, took out a glass container and started pointing at it animatedly. ‘What is this?’ he asked, before taking a second identical container from the fridge and waving it around. ‘And this, what is this?’

‘Rice,’ I said.

‘Exactly,’ he said defiantly. ‘And I will reheat some tomorrow, and the next day and the next day.’

Like many Iranians, my dad takes rice very seriously. When we cook polow together, he says things like ‘Careful!’, ‘Be gentle!’ and ‘You need to keep an eye on your rice, Mister!’ as if we were bathing a newborn baby. Despite having been divorced for twenty-nine years, his ex-wife – who is British and, incidentally, my mother – still cooks perfect Iranian-style rice due to how ardently she was drilled on his methods. When asked if he owns a rice cooker, he takes great pleasure in saying: ‘You’re looking at it.’

According to the food52 video, you should eat rice within a day of cooking it. After that window has passed, they advised viewers to ‘just throw it away. Just throw away your leftover rice, friends, it’s really not worth it.’ They’re not the only ones making this claim. On LADBible, a headline read: ‘“Fried rice syndrome” is real and can kill you, doctor says’. A post on the ‘r/TrueOffMyChest’ subreddit titled ‘I almost died from fried rice syndrome’ tallied over 500 replies. If you look at the comments on these posts, you’ll find lots of astonished people – frequently of Middle Eastern, Asian, African or South American descent – saying something to the same effect as Dad: I’ve reheated rice all my life, and I’ve never got ill. How can this be true?

This stark division in rice-reheating attitudes is almost comically widespread. While appearing on The Graham Norton Show in 2023, the British and Malaysian-Chinese stand-up Phil Wang joked that the main difference between white people and Chinese people is that the former are ‘absolutely terrified of reheating rice. For white people, rice has one chance to be food. And if there’s any left over after the meal, it just becomes poisonous straight away.’ Out of curiosity, I texted seven white friends to ask if they were brought up to believe that reheating rice was dangerous. All seven said yes.

Like my dear father, and Phil Wang, I have also been reheating rice all my life. As I write this, there is one container of rice in my fridge, and three in my freezer. Cooked white grains linger in my kitchen like coins in trouser pockets: forgotten for long periods, then rediscovered with joy. And I have never, to my knowledge, got sick from them.

As I plied Dad with more and more internet evidence of rice-related anxiety, he fell silent. We looked out the window into the back garden. The closing notes of the day’s sun played out on the grass. ‘China, India, Pakistan, Iran,’ he said, quietly. ‘Russia, Greece, Turkey, Japan,’ he continued, becoming louder and bolder. ‘Malaysia!’ I realised he was listing countries that ate rice. ‘There would be a lot less people in Iran if reheated rice was deadly. There are communities in Iran that are so poor, they eat rice for breakfast, lunch and dinner. They don’t have a fridge or a chiller. How can you explain that, Joseph? How?’

Of course, this wasn’t the first conversation I’d had about the dreaded syndrome. But I’d always thought that it was only a risk if you didn’t cook your rice properly in the first place, and so I’d dismissed it, with an air of superiority, as something not worth worrying about. But as the odd cultural divide became more apparent, my curiosity was piqued. How can so many people be terrified of reheated rice, while others live their lives in fluffy ignorance? Are the warnings overblown or have I – and most of the non-Western world – been dancing with death all these years? Is there something in the way that different cultures cook or store rice that protects against these toxic side-effects? And where did the very specific – and rather problematic – name fried rice syndrome come from? I felt compelled to find some answers.

Reheated rice fears have circulated for decades, but many of the recent posts on TikTok and other platforms seemed to have been triggered by the recirculation of a story about a young man in Belgium supposedly dying from fried rice syndrome. Despite regularly inspiring breaking-news-style posts – ‘Man, 20, found dead in his bed by devastated parents after he reheated common pasta dish’ reads a headline in the Sun from 2023 – the incident actually took place in 2008. As that headline reveals, the man hadn’t actually eaten rice, but leftover spaghetti (resulting in some online publications running confusing headlines like ‘20 Year Old Dies of “Fried Rice Syndrome” After Eating Leftover Pasta’). I texted the same seven friends from earlier to ask if they’d ever received warnings about reheating pasta as they had for rice. All seven said no.

According to a 2011 report about the case in the Journal of Clinical Microbiology, the man became sick after eating spaghetti leftovers that had been cooked five days earlier and then left in the kitchen at room temperature. Within 30 minutes of eating, he experienced a headache, abdominal pains and vomiting. He was found dead the following morning. The autopsy revealed the presence of the bacterium Bacillus cereus (B cereus), which was also detected in samples of the pasta dish that were analysed. The paper also references four other fatal cases attributed to B cereus food poisoning: two more associated with pasta, one with fried rice and one with noodles.

‘B cereus is the microorganism culprit behind the so-called fried rice syndrome,’ confirmed Enzo Palombo, a microbiologist at Swinburne University of Technology in Melbourne, whom I spoke to over Zoom. The name comes from Latin: ‘Bacillus’ means ‘little staff’ or ‘little wand’, while ‘cereus’ means ‘wax-like’. In your mind, picture a microscopic sausage that glistens and wiggles and can multiply into endless sausage links, and you’re not far off. B cereus is a close relative of the notorious Bacillus anthracis, responsible for anthrax. ‘Most of the time, it’s a benign presence,’ said Palombo. ‘But when the conditions are right, it has a few tricks up its sleeve that allow it to act as a food pathogen.’

Most food-borne bacteria are destroyed by heat during cooking, Palombo informed me. But B cereus is one of a few species capable of forming spores. ‘These spores are incredibly resilient: they can last for hundreds of years, and can resist acid, heat and other environmental conditions. They think they might even be able to survive in outer space.’ No matter how hot your stove, the spores of B cereus can survive in your food in a dormant state, waiting for an opportune moment to return, like a cryogenically frozen billionaire.

How do dormant spores turn into a nasty bout of food poisoning? According to Palombo, the ‘danger zone’ in microbiology is between 5°C (the temperature of the fridge) and 65°C (the temperature that food should rise above when cooked). ‘So, imagine you’ve cooked your rice or pasta and there is B cereus in there. You’ve killed the bacteria through cooking but the spores have survived. If you chill it right away, then you’re fine, if you reheat it properly then you’re fine,’ he told me. But if you leave it at room temperature for too long and there’s sufficient moisture, then the spores spring back to life and begin feeding on the starch while secreting toxins. ‘Bingo,’ Palombo continued, ‘these toxins are what will muck up your guts and cause you to have diarrhoea, vomiting or even more severe consequences.’

It’s worth emphasising that the Belgian case was rare and extreme – B cereus infection is usually mild, and hospitalisations are infrequent. The global mortality rate for cases associated with food poisoning is just 0.05%, and deaths generally occur in those predisposed to developing more severe illness (young people, old people, pregnant people and people with compromised immune systems).

Much of what Palombo and I talked about – danger zones and safe storage – felt intuitive. I don’t leave food out for hours. I divide big batches of cooked rice into smaller boxes so that it cools quicker. I always keep everything in either the fridge or freezer, and always thoroughly reheat. But I still felt deeply puzzled about some things. If B cereus is a risk with any starchy food, then why aren’t we as fearful of reheated pasta as rice? And if reheating rice does carry this potential to cause illness, why is the perception of risk so inconsistent across cultures?

‘It’s something I’ve always known about, but that just comes from a catering background,’ said Farokh Talati – Head Chef at St John Bread and Wine in London and author of the cookbook Parsi: From Persia to Bombay – when I asked him about rice anxiety. ‘Rice is the cornerstone of my cooking,’ he told me. ‘In my own home life, I’m loose. I’ll cook my rice, and put the leftovers in the fridge once it’s cooled down. When I heat it back up, I’m not there probing it, I just put a bit of coconut oil in a pan, fry the living crap out of it, and then eat it.’ But when it comes to his professional life, Talati has to be much more cautious, because of strict health and safety regulations. ‘But it’s not so much around just rice itself – it’s around everything we touch from raw foods to raw vegetables.’

I asked Talati if he had any theories about why rice might have acquired such a unique fear factor? He responded, ‘I can’t help but think: Is there something deeper going on? Is it something about how the West perceives the East? Is there something really ingrained in us here that sees rice as a scary thing, an unknown thing? What is this food that’s coming over? It’s not part of our cuisine – is it making us sick?’

Throughout history, rice has certainly been known to trigger animosity among Europeans. Friedrich Nietzsche wrote that eating rice caused one to become addicted to opium. The notable French gastronomist Jean Anthelme Brillat-Savarin – famous for his aphorism, ‘Tell me what you eat, and I will tell you what you are’ – thought eating rice made you soft and cowardly. Meanwhile, in his 1883 pamphlet, How, When and What to Eat: A Guide to Colonial Diet, the Australian doctor and novelist Stephen Mannington Caffyn cautioned that ‘We might expect to find rice-eaters everywhere a wretched, impotent, and effeminate race, and such is the case.’

It is certainly odd that food poisoning caused by B cereus has become so widely known as fried rice syndrome – a term used not just on social media and in news coverage, but even in peer-reviewed academic publications. I found it difficult to trace the exact historical origin of the name. The first complete scientific proof of B cereus as a microorganism capable of causing food-borne disease came in 1955, in Norway, and had nothing to do with rice – it was traced to a vanilla sauce prepared from corn starch that had been linked to a wave of illnesses in care homes and hospitals in Oslo.

One of the earliest associations between B cereus and fried rice that I could track down was a 1973 article in the British Medical Journal that reported on eighteen outbreaks of food poisoning in the UK dating back to 1971, many of which had been traced to Chinese restaurants and takeaways where boiled rice was being stored at room temperature for long periods of time before being fried. But the phrase ‘fried rice syndrome’ was nowhere to be seen.

Around the time that this article was published, a completely separate food scandal associated with Chinese food had erupted, with misplaced fears about MSG stoked in the US by anti-Chinese racism and dodgy science. In a 1968 letter to the New England Journal of Medicine, Dr Ho Man Kwok wrote: ‘For several years since I have been in this country, I have experienced a strange syndrome whenever I have eaten out in a Chinese restaurant,’ before going on to describe symptoms that included numbness at the back of the neck, general weakness and palpitations. While Kwok posited MSG as only one possible cause among many, it was latched onto by scientists and the media. In 1969, experiments – now found to have been crucially flawed – appeared to confirm ‘Chinese Restaurant syndrome’ as a legitimate medical condition caused by MSG, one that could make you sterile and cause brain damage in babies. The subsequent public health scare lasted for decades.

It doesn’t feel like a stretch to posit that fried rice syndrome may have been coined during this racially charged moment in culinary history, in which food safety fears were being rampantly fuelled by a dislike and distrust of immigrant culture. ‘I think there is a bit of a stigma in how it has come to be named fried rice syndrome,’ said Palombo. ‘It seems to suggest that Asian food is the problem, but it’s not. Any starchy food should be considered a contamination risk.’

I was starting to understand how reheated rice, specifically, had become such a uniquely panic-inducing food for white people. But if beneath the noise there was still a very legitimate danger of food poisoning, why was this risk being so little discussed, underplayed or even ignored in other cultures? In essence: Why was my dad angry about this?

‘I had no idea this was a massive thing until I read your email,’ said Mandy Yin, founder of the Malaysian restaurant Sambal Shiok in North London, after I sent her links to the TikTok rice panic. At the same time, it didn’t surprise her. ‘Years ago, I was with my husband’s family – half Scottish, half Welsh – and we ordered a massive Chinese takeaway. Immediately after finishing, everyone refused to keep the rice. I was like: There’s so much food being wasted!’

Yin told me that at Malaysian street food stalls and markets, the rice for nasi lemak is often cooked in the morning, wrapped in banana leaf parcels along with sambal, peanuts, anchovies, and egg, and then sold throughout the day. In fact, in many cuisines, there is an abundance of recipes in which leftover rice is actively preferred over freshly cooked.

A beloved dish in Tamil cuisine called pazhaya sadam literally translates as ‘old rice’. Food writer and novelist Chitrita Banerji told me of a similar recipe in rural Bengal called panta bhat: ‘During the summer, people will pour water over leftover rice and just leave it – not in the fridge, but outside. The hot temperature outdoors will ferment it to create this kind of milky liquid. You eat it with raw onions and maybe some raw green chillies. It has a sharp, slightly funky taste. And that is considered very healthy and cooling for your body.’ I find it hard to believe that these recipes, widely circulated and often passed down through generations, would have survived if they were inherently poisonous.

Comparing the rates of B cereus poisoning between different countries didn’t help to clear things up much. At first glance, when you compare a Western nation like the US with China, the world’s leading consumer of rice, the data are striking. According to a US Centers for Disease Control and Prevention estimate from nearly twenty years ago, around 63,400 B cereus episodes occur annually in the US, whereas a ten-year survey of infections in China (from 2010 to 2020) logged only 7,892 cases in total. That suggests that far more people are getting sick from fried rice syndrome in the US than in China (particularly when the population discrepancy between the two is factored in). However, the methods used in these studies are so different as to basically preclude comparison – whereas the US figure is an estimate to account for likely under-reporting of mild cases, the Chinese survey focused explicitly on confirmed cases. Still, I couldn’t help but wonder: Might there be something in how different cultures are preparing and cooking rice that may somehow be preventing B cereus infections?

Searching for answers, I came across the work of Paul W Sherman, a biologist at Cornell University who spent a large chunk of his academic life studying the social life of naked mole rats. In the late 1990s, he collaborated with a graduate student called Jennifer Billing to investigate a uniquely culinary question: Why did humans start using spices in food? And why, despite a now-established global spice trade, is their use far more important in some cuisines rather than in others? Could it be, they posited, that people in hotter countries use more spices because spices kill bacteria that grow faster in warmer climates, keeping their food safer to eat?

Sherman and Billings surveyed 107 ‘traditional’ cookbooks from thirty-six countries globally, creating a database of nearly 7,000 recipes, across which forty-two spices were used. Their analysis found that countries with higher average temperatures appeared to add more spices to their recipes relative to countries with lower average temperatures. They also discovered that higher average temperatures (where food-borne pathogens would be more prolific) were associated with the use of spices with stronger antimicrobial effects. They concluded that beneath the veneer of cultural differences in taste preference, culinary spice use might also have an evolutionary premise.

It’s certainly rare that I cook plain rice without any spices added at all. I’m usually riffing on one Iranian recipe or another, which almost always involve turmeric, sometimes saffron and occasionally clove, cinnamon, ginger or cumin. Likewise, when Talati told me how he cooked what he described as ‘plain rice’, it still involved ‘boiling it with spices like star anise, cinnamon, clove and cardamom’. Similarly, Yin said that, when cooking rice, ‘I do generally always use garlic and white pepper, oyster sauce and soy sauce, and some sort of chilli sauce or sambal feature regularly too.’

Star anise, clove, cinnamon, turmeric, ginger and garlic have all, in peer-reviewed scientific papers, shown antimicrobial effects that inhibit B cereus in some shape or form. And they aren’t the only ones: similar studies are out there for the antimicrobial effects of ingredients including rosemary, black pepper, coriander, oregano, thyme, galangal, onion, capsicum and pomegranate (a popular ingredient in Iranian cooking). Even the banana leaf, mentioned by Yin as packaging for parcels of rice, displays antimicrobial properties, although I couldn’t find any studies of its effect on B cereus specifically.

Could the use of certain spices in various cultural methods of rice preparation be preventing the proliferation of fried rice syndrome? I put my spice thesis to Palombo. He agreed that traditional medicinal plants have a lot of antibacterial compounds. ‘Before modern methods of food preservation, people would rely on stuff like this,’ he said. ‘Salt is also an inhibitor of microbial growth, so if you’re adding salt to your rice when you cook it, that might have an effect too.’ I started to think of all the Iranian recipes I cook at home, which my dad taught me and his mother taught him, as not just guides for good meals, but as repositories of traditional knowledge, from a time before fridges and microwaves, in which many of the ingredients had been combined in particular ways for a myriad of now-forgotten-yet-essential reasons. And like a child reciting a prayer, I was now repeating these actions, without ever truly understanding why.

The spice theory is interesting, but it is just a theory. Since Billing and Sherman published their work in the nineties, some of their findings have been challenged. A 2021 study in the journal Nature Human Behaviour painted a more complicated picture, which suggested that spice use is better predicted by socioeconomic factors like poverty and poor health outcomes than by temperature or infection risk. And when I asked Banerji about the use of spices to cook rice in Bengal, she was quick to burst my bubble: ‘In Bengal, the day-to-day rice is cooked plain, without any added spices or even salt. The use of cinnamon, cardamom, cloves, bay leaves, or even saffron is seen for more “fancy” recipes, like pilafs and biryanis. It is not daily food.’

How then to think about fried rice syndrome after everything I’d learned? It was certainly more complicated than a simple public health warning. The name itself is useless and misleading, and probably originates from a particularly racist moment in culinary history. Yes, improper storage and reheating of your rice can make you sick, but so can the same treatment of any starchy food. I’d become less wary of rice in particular, and more wary of room temperature itself. Will I now think twice about the tempting arancini and frittatina di pasta that sit out on cafe counters in Italy next time I’m on holiday? Yes. Will I try at least one anyway because risk excites me? Yes.

I walked away from this intensive phase of research with a very odd picture of the world, one divided into two tribes: the reheaters and the dumpers. Box by box, the faithful reheaters filled their fridges and freezers with cooked rice, building for the future, like beavers constructing a mighty dam. Meanwhile the other tribe, the fearful dumpers, poured their leftovers into a never-ending waterfall of perfectly edible white grains that showered down into a black abyss, deep into the underworld.

That evening, once Dad had calmed down, we did what we do best: we cooked rice. He’d been to the Kurdish shop on Sunderland Road to get fresh dill and fava beans so that we could make baghali polow, an Iranian rice dish that people have been cooking since at least since the Safavid Dynasty. We washed basmati ritualistically five times and then parboiled it. Steam bellowed from a big pot, dill leaves were separated from stalks, fava beans were rinsed. We drained and washed the parboiled rice again, then mixed it with the dill and beans. We added oil, butter and turmeric into the pot, carefully placed and sizzled some thinly sliced potato and delicately spooned the rice back in. Dad said, ‘Careful!’ a lot. Melted saffron was drizzled over, and then the lid went back on for an hour.

We ate the baghali polow together and watched the football, and Dad told me all his rice memories: about being taught to cook by his mum; about living in a Caspian seaside town in Mazandaran and smelling the rice fields in the summer (‘a lovely sweet smell’); about how in Iran, your Sunday best clothes that you’d wear for special occasions are called ‘lebas polo khori’ – ‘rice-eating clothes’. When the game finished and I got up to leave, he presented me with three glass containers of leftover baghali polow, which I took home, and which I would ultimately reheat, the next day, and the next day and the next.

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Joe Zadeh is a British-Iranian writer based in the north east of England. He writes fast-paced and wide-ranging nonfiction about the things that underpin our everyday lives, but often escape scrutiny. His longform essays have questioned the way we think about time, examined the cultural history of charisma, and shone a light on the consequences of the modern world's addiction to concrete. Previous bylines include the Guardian, VICE, and Rolling Stone. He currently works as a contributing writer for the US publication Noema.

Ibrahim Rayintakath is an illustrator and art director based in his coastal hometown of Ponnani, India. His editorial work, which explores themes of culture, politics and mental health, has appeared in various outlets like the New Yorker, the New York Times and NBC.

I almost failed one of my first year university mathematics exams. I suspect some people have a vision of university maths as just doing bigger calculations. More numbers. Longer equations. Solve for x, y and z.

But new undergrads soon hit a steep new learning curve with what’s known as ‘mathematical analysis’. Suddenly, maths is no longer just about performing calculations; it’s about building rigourous proofs.

This means being able to solve problems like the below:

Let (a_n) be a real sequence. Prove that if (a_n) converges to both L and M, then L = M.

Now you might be thinking ‘well if (a_n) converges to both L and M, then it’s obvious L=M’. And if you thought this then, much like first year undergraduate Adam, you’d leave the exam with very few marks1.

There’s good reason for demanding such rigour; in the 19th Century, many theorems assumed to be ‘obvious’ would end up collapsing when they encountered concepts like infinity. It would take mathematicians like Karl Weierstrass, Bernhard Riemann and others to put things back on a solid footing, and make sure proofs behaved even when dealing with things that were infinitely small or infinitely large.

Over time, I learned how to be good and rigorous at mathematical analysis, and by the end of my degree, these exams produced some of my highest marks. In turn, I’d spend my PhD getting better at Bayesian inference, a topic that I didn’t focus on so much as an undergrad. In the process, some previous expertise fell by the wayside. If you’d asked me in sixth form to write down Newton’s equations of motion off the cuff, it would have been easy for me. But if you asked me as a PhD student, I’d have had to look them up.

Exams that were once hard had become easy, and vice versa. I remember one morning during my PhD, I’d been sat discussing some questions from that year’s Sixth Term Examination Paper (STEP) with my fellow students. STEP is an exam for A-Level students hoping to get on to leading UK maths degree courses; it’s designed to reach beyond school level, examining university-like mathematical thinking. It’s administered by the University of Cambridge, and PhD students would often help out with marking.

When I’d taken STEP at school, I’d found the physics questions easiest. The main challenge was adapting familiar equations to new questions. Conceptual proof-like problems about properties of numbers or functions seemed much harder. Yet when I looked over that STEP paper years later in the Cambridge coffee room, it hit me that the opposite was now true. The abstract questions now seemed easy and the physics questions drew a blank. I’d forgotten the physics equations I’d rote-learned, while building the logical toolkit I needed to tackle pure maths questions.

In other words, my ability hadn’t increased evenly; it had become spiky. Training to build depth in one area had come at the cost of breadth in another.

This ‘spikiness’ in knowledge is now a common theme in discussion of AI skill. For leading models, the performance profile isn’t rounded - it sticks out far in certain areas, and not much at all in others.

This isn’t an accident. AI models are effectively targeting top marks on the same narrow set of exams. And that makes it difficult to define what ‘good’ means.

In a recent post, pointed out that many LLM performance benchmarks aren’t necessarily as impressive as they might seem. Take the AIME 2025 mathematical benchmark, with questions taken from the 2025 American Invitational Mathematics Examination. GPT-5.2 scored 100% in AIME 2025. As Sukhareva notes:

But could OpenAI fine-tune their model on AIME 2025 to get 100%?

They don’t even need to. The questions and answers are all over the internet. These thirty questions are public, they could have just trained on them or fine-tune an already-trained model on it if the dataset was published after knowledge cut-off.

If this is the case, it’s like a student boasting they’ve got top marks on a past exam paper, after having used that same paper as a revision tool.

This can explain why LLMs that appear very good at some narrow tasks can perform very poorly on others. When learning is focused on a narrow region of the space of possible problems, it can deliver impressive results so long as the task remains stable and repetitive. But, much like a maths student relying heavily on past exam experience, it can lead to confident overfitting when the structure of the problem changes.

This can also be true of human expertise. Great pure mathematicians may struggle with data-driven problems. Strong statisticians may be uncomfortable with physics. Talented physicists may be weak at pure maths.

The reason researchers poured so much effort into the field of mathematical analysis in the 19th Century? They wanted to be confident that their results would actually hold true. They didn’t want awkward counterexamples – or ‘mathematical monsters’, as some called them – to come along in future and trample on their work.

But the spikiness of AI knowledge, and risk of overfitting to narrow tasks, means we don’t currently have that confidence when it comes to artificial skill. What seems like ‘good’ performance in one situation won’t necessarily translate to another. We may get mastery – or we may get a monster.

If you’re interested in reading more about Weierstrass, Riemann and mathematical monsters, you might like my latest book Proof: The Uncertain Science of Certainty.

Cover image: Antoine Dautry

Far Side fans might recall a classic 1982 cartoon called "Cow Tools," featuring a cow standing next to a jumble of strange objects—the joke being that cows don't use tools. That's why a pet Swiss brown cow in Austria named Veronika has caused a bit of a sensation: she likes to pick up random sticks and use them to scratch herself. According to a new paper published in the journal Current Biology, this is a form of multipurpose tool use and suggests that the cognitive capabilities of cows have been underestimated by scientists.

As previously reported, tool use was once thought to be one of the defining features of humans, but examples of it were eventually observed in primates and other mammals. Dolphins can toss objects as a form of play which some scientists consider to be a type of tool use, particularly when it involves another member of the same species. Potential purposes include a means of communication, social bonding, or aggressiveness. (Octopuses have also been observed engaging in similar throwing behavior.)

But the biggest surprise came when birds were observed using tools in the wild. After all, birds are the only surviving dinosaurs, and mammals and dinosaurs hadn’t shared a common ancestor for hundreds of millions of years. In the wild, observed tool use has been limited to the corvids (crows and jays), which show a variety of other complex behaviors—they’ll remember your face and recognize the passing of their dead.

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