Even before she became a mathematician, Hannah Fry had strived to live her life by logic. Her most memorable fight with her sister when they were teenagers was over “the optimal route” home. She used to say that if there was a nutritionally complete pill to replace food, she would take it.
She even came up with a “mathematically informed” seating plan for her wedding, crunching factors such as age, political persuasion and predicted alcohol consumption to decide which guests should share a table.
Numbers had always brought Fry clarity, a sense of control, even comfort. Then, in January last year, she found the stats working against her. A routine smear test, followed by a biopsy, had confirmed cervical cancer. She was 36 at the time and had two young daughters.
The day of her diagnosis was a “total out-of-body experience”, Fry says. She would have to wait for results of the crucial scans, showing whether the cancer had spread. In the meantime, she had an essay due to the New Yorker – “literally that night”.
Fry recalls an intense evening, “sitting on my bed, drinking really heavily, crying and writing”. What was the essay about, I ask? Fry peels into laughter. “It was about the limits of what data can tell us.”
As a writer, broadcaster, lecturer and presenter, Fry has made her career out of demystifying figures and data so that they might be put to use in society and our everyday lives. Within that remit, however, her interests are broad and apparently boundless – and often ahead of the curve.
As a regular presenter of documentaries for the BBC, Fry has turned her informed enthusiasm to subjects as varied as the logistics of aviation and the science behind supermarket use-by dates.
The Curious Cases of Rutherford & Fry – her podcast with the scientist Adam Rutherford, answering listeners’ questions such as “is dark matter a fudge?” – recently concluded its 20th series, and will return for another in the new year.
In her new BBC Two show, Secret Wonders of the Modern World, she looks into inventions and innovations that we may be taking for granted – starting with bank cards.
Fry greets me from the back of a car bound for the BBC, her hair still only half-styled ahead of a shoot. She didn’t realise we were going to be talking with video, she explains merrily: “I thought I’d leave my pin curls in because I thought no one was going to see me.”
For all the glamour of working in TV and radio, Fry still considers herself “a mathematician, first and foremost” – and a celebrity “only if you like extremely niche maths videos on the internet”.
But beyond that, she admits, she struggles to define her focus or preoccupation: “The phrase that I use is that I am intellectually promiscuous.”
Fry has always had this voracious appetite for knowledge. She grew up in Ware, Hertfordshire, “very working-class”: her English father made hydraulic lifts for trucks, and her mother, an Irish immigrant, stayed at home.
“Education was always, in our family, the number-one priority,” says Fry. When she was about 11, her mother made her complete one page of a maths textbook for every day of the summer holidays.
She tells this story with such delight that I question its veracity. “Oh, I was not happy about it, believe me,” she says. (Her 2018 book, Hello World: How to Be Human in the Age of the Machine, is dedicated to her mum: “Thank you for never taking ‘no’ as an answer.”)
Fry studied mathematics and theoretical physics at UCL, followed by a PhD in fluid dynamics. She became a lecturer there in 2012, and is now a professor in the mathematics of cities.
But Fry was never a “natural mathematician”, she says: what drew her in was data as a means of storytelling and shedding light on the world. Fry’s breakthrough moment was in 2014, when she gave a Ted Talk on “the mathematics of love”, using probability to find a partner and finding a statistical approach to relationship satisfaction.
“It was the kind of thing that I found funny and that I’d joke with my friends about – how I’m going to optimise my dating strategy.” (She and her husband were, in fact, set up by friends.)
The Ted Talk has now been viewed nearly 7m times; Fry still receives messages taking umbrage at her suggestion that, if you are still with your first ever partner, you are best off breaking up. “It’s always slightly tongue-in-cheek … The numbers will only ever take you so far.” At the same time, as Fry says in the clip, there is no other possible strategy that can do any better.
That is the common thread, across all of her projects and platforms: the unexpected intersections of data and humanity – especially where there might be real-world applications.
“A really crunchy textbook” can hold as much interest and excitement for her as a potboiler, she says. “It’s almost as if I’ve got this incredibly juicy bit of gossip that I want to share with everybody.”
Often, Fry has played the part of a sympathetic go-between for those lay people who can’t make sense of numbers and the experts who struggle to see past them. But in the past two years she has started to see the limits to playing interlocutor – and even data itself.
“Ultimately, every decision is an emotional one,” she says. “You might have an emotional reaction to the data, but you can’t put them on either side of a weighing scale and expect them to balance – they just don’t.”
That has been a “learning curve” for her, too – accelerated by the pandemic, and cemented by her experience of cancer. She may have understood the discussion of probability better than most patients – but in such circumstances, “all of your training disappears”, Fry says.
“Really honestly, when you’re in that position – it doesn’t matter whether you have a PhD in mathematics or you dropped out of school aged 12: every single person is just frightened about their future, thinking about their family and the people that they love.”
Fry faced particular uncertainty. Her scans had been ambiguous as to whether the cancer had spread to her lymph nodes – “and whether it had, or hadn’t, made a dramatic difference”.
If the cancer had reached just one lymph node, her stage-one diagnosis immediately jumped to stage three, substantially decreasing her chances of survival, and again with each node thereafter.
Fry was advised to proceed on the assumption it had spread and to undergo a radical hysterectomy, removing not just her uterus and “a long list” of its surrounds, but also all the lymph nodes in her pelvis. After her surgery, she was told that four or five of her lymph nodes were swollen, indicating cancer had already reached the lymphatic system. “I was in there like: ‘Right, game over: it’s done,’” she says.
She spent a sleepless week in hospital, in isolation due to the need to shield from coronavirus. It was “horrendous”: “The surgeon had basically told me that things weren’t looking good … and I was just there, paralysed in place, mentally and physically.”
But, two weeks later, scans showed that the surgery had been successful: “I had somehow got away with it.” She sounds as if she still can’t believe her luck.
Fry has now been in remission for more than a year. “Not to be too grandiose about it, but I do think that, actually, my worldview has really shifted in the last couple of years. There’s a really nice line: ‘Life isn’t a problem to be solved, it’s an experience to be had.’”
As glad as Fry is to be alive, however, she feels ambivalent about how the risks were communicated to her.
“I was only ever told what the numbers were; I was never given the numbers in order to give myself a choice,” she says.
After surgery, Fry developed lymphoedema: a chronic condition affecting the lymphatic system that causes swelling of the limbs and requires lifelong daily management. It was presented as a possible side-effect, Fry says – but, relative to potentially terminal cancer, a problem she’d be lucky to have. The choice, as it was put to her, seemed to be to have the hysterectomy, or to go without – in short, whether to live or die. “At no point did I realise that actually there is an entire series of steps between one and the other,” she says.
Fry was fortunate in being able to afford an experimental surgery (costing about £15,000) that has significantly alleviated the impact of the condition. But the feeling that she was steered towards an outcome that she never fully understood lingers.
“I’m not saying that I would necessarily have made a different decision – but I would have liked to have been involved in that decision.”
To Fry, it highlighted the importance of acting as your own advocate within the health system; she produced her intensely personal BBC Horizon documentary, Making Sense of Cancer, with that in mind.
“There is a much more patriarchal approach to medicine outside of maternity, where we just sort of nod and agree, and later wonder if it was really right for us.” She sighs. “Is it too much to ask that you really understand the risk of lifelong complications?”
In a perfect world, Fry suggests, patients who needed to make consequential decisions about their health would be able to sit down with a consultant who had a strong grasp on probabilities, “and have a conversation: ‘What is most important to you? What are the aspects of your life that you most want to preserve, and how can we find the best path for you?’ That, for me, is what really informed consent is.”
But reaching such an understanding takes not just resources, but a readiness to listen and learn.
Without making an effort to understand other people, Fry says, with mounting impatience – “you are just not going to get anywhere. You’re both playing tennis, but you’re on different courts.”
She saw this herself earlier this year while making Unvaccinated, a BBC Two documentary about Britons who had refused the Covid-19 vaccine. One reviewer suggested that Fry deserved a “Bafta for most patient TV host”.
In fact – she says, sounding rueful – that week she learned that she was a lot less patient than she thought she was. “I went into it being probably more understanding and respectful of unvaccinated people than my peers … I held it together, but I really struggled.”
The interviewee who made the greatest impression on Fry was Chanelle, a black woman from Lambeth in south London, who said that the vaccination centres resembled prisons.
“She was saying: why would you voluntarily put yourself into that kind of triggering environment, for something that you don’t feel like you need? I could not agree with her more – and until she had said it, I just had never seen it that way.”
Yet doctors tried to bring Chanelle round to the vaccine with figures about its safety, as though that was a response to her concern. “There is an emotional response, and you have to respect that and understand that,” Fry says, with frustration.
“You have to make people feel like they are properly included and listened to if you want them to go with you – and I think, actually, that’s a really big mistake that we’ve made.”
The most obvious example of this failure of communication is the pandemic. Fry had been unexpectedly across the threat, having set out to predict the impact for Contagion: The BBC Four Pandemic in 2018. The large-scale data collection she led as part of the citizen-science experiment ended up being applied to Covid-19 research two years later.
She remembers shouting at her TV as impenetrable graphs – in one case, “actual nonsense equations” – were flicked through at speed during the government’s press conferences. Sometimes, Fry says, she felt stats were being used as set dressing, “to give themselves an air of authority”. “They know that this is stuff that people find really difficult and intimidating and so they used it almost to close off discussion. I think that was the wrong thing to do.”
She chooses her words carefully, finally pulling out her pin curls as her car approaches the BBC. Top-down communication no longer works any more, she says: “Trust now has to be much more about a relationship.
“That means being transparent about what you’re not sure about, and being honest and open about the bad stuff as well as the good stuff – because I think that is the only way to get people to genuinely believe you.”
Happily, for now, Fry is able to focus on the good stuff with her new series celebrating innovations. “The world is so blimmin’ depressing, all of the time … This is genuine but well-founded glee at the things that we have achieved.”
In showing us how much we take for granted now, it might also present possibilities for the future. When I ask Fry for a statistic that keeps her up at night, she does not need to think long: 1.5C.
“That’s one version of the future – but I do honestly believe that there is another version possible, one where we are using mathematical algorithms and artificial intelligence to take salt out of water, or turn the Sahara back into a rainforest … The technology is starting to accelerate, and if you can get that to work, then you are in a world of abundance.”
I ask her if she could have one aspect of maths magically understood, what would it be?
She gives real thought, savouring the possibility, and settles on a simple concept of probability: “If something has a 95% chance of happening, and it doesn’t happen,” Fry starts to titter, “you shouldn’t be surprised.”
Secret Wonders of the Modern World starts on Thursday 10 November on BBC Two and BBC iPlayer
