Stuart Firestein worked in the theatre industry before turning his hand to neuroscience.

Julie Dunne was perfectly happy as an accountant, yet she always felt as if there were some other type of work that she would adore. “I just didn't know what it was,” she says. Then, in the early 2000s, Dunne participated in field expeditions run by the worldwide environmental organization Earthwatch — and discovered that scientific research enthralled her. The 57-year-old is now a postdoctoral researcher at the University of Bristol, UK, studying the chemistry of ancient pottery to determine early eating habits.

The decision to start science later in life comes with challenges: a mature student may have to go back to secondary- or undergraduate-level classes to pick up necessary qualifications. They might have to rejig their financial or living situations to support a science career. They have less time to build up a CV and research programme, and they may have to combat ageism when it comes to securing a job.

But older students have advantages, too, such as maturity, drive and unique experiences and networks. The best way to explore a new career, say many, is to try out an evening science class or two, maybe a master's programme, before diving full-time into a PhD. Those who have trod this path say that although it might have been daunting and involved sacrifices, it was worth doing. “I love what I do,” says Dunne.

Dunne is far from alone in her late-life scientific endeavour. Some people don't discover their passion for science until they've already settled into a different career. Others love science, but aren't ready for a PhD when they finish university. Still others cherish the goal of a tenured academic position but, owing to stiff competition, take decades to get there.

Doctor in waiting

Most doctoral students are in their 20s or 30s, according to data from the US National Science Foundation (NSF), the European Council of Doctoral Candidates and Junior Researchers and the European University Institute. But there are plenty of older students, too. According to the NSF, 5.3% of PhD recipients are between 41 and 45, and 8% are older than 45 (see 'Doctoral data'). And the European University Institute data indicate that in many countries, it's rare for students to complete a PhD before hitting 30, and not uncommon to be older than 50 before becoming a senior professor.

Dunne dipped her toe into science more formally in 2005, at the age of 45, when she began evening and weekend classes in the sciences that qualified her to apply for an undergraduate degree. From there, she carried on through her bachelor's and PhD programmes at Bristol. “I was terrified at first,” she says. But although her fellow university students had come straight from undergraduate programmes, Dunne had drive. At the beginning of every term, she and her peers received a guidance booklet for each class that listed reading and course criteria. She devoured them from cover to cover — and was surprised when her younger counterparts did not do the same. That sense of determination is the key to success, she advises. “You've just got to be committed.”

Stuart Firestein, a neuroscientist at Columbia University in New York City, has noticed similar traits among his older postbaccalaureate students, who take courses at the university after earning a bachelor's degree. At Columbia, they pay for each class individually, rather than for blanket tuition as do undergraduates, and they want the most value for their investment. They're more focused, he says, and often treat the class as if it were a job.

Firestein came to science relatively late, too. He had always been interested in science and had considered a career in astronomy as a child, but in high school, he developed a love of theatre and worked in that industry for nearly 15 years.

When he was 30, he was stage-managing and doing lighting for a successful production in San Francisco, California. During the day, when he was free, he began to study animal behaviour at San Francisco State University. He earned a biology degree, then left the theatre to pursue a PhD in his late 30s, followed by a postdoc.

Firestein says that his theatre background turned out to be an advantage in some situations. For example, his skill at learning scripts helped him to memorize organic-chemistry reactions. And after the failure inherent in the theatre business — a poor performance one night, for example — a botched experiment was no big deal. (He even wrote a book on the topic called Failure: Why Science is So Successful, Oxford University Press, 2015.)

A slow start

Later-stage students may find it helpful to ease into the process slowly, says Robert Hevey, 63, who is studying plant biology and conservation at Northwestern University in Evanston, Illinois, and the Chicago Botanic Garden in Glencoe, Illinois. He took time to work up to his doctoral studies during his former career in business and finance. In the early 2000s, he enrolled in a plant conservation and biology certificate programme at the garden. Then he studied for a master's degree at night school, taking one course per quarter over six years. Only then did he leave his job to pursue a PhD. Hevey says that in the United States, community-college and non-degree courses can help an older student to decide whether a doctoral-degree programme is the right choice.

But there's one crucial question to ask even if those classes go well, Hevey adds: “Can you afford it?” Hevey could embark on the PhD — for which he sought no stipend — only because he was in shape to support himself for the rest of his life.

Source: NSF

For some, the move back to education may involve down-sizing. When Dunne moved from Newton Abbot, UK, to Bristol to begin her undergraduate degree, she bought a much smaller flat than she'd occupied before. “I had the oldest, smallest, cheapest car you can think of,” she says. Although Dunne loves fashion, she cut back her spending on clothing.

“It's certainly not been a good move for me financially, really, because I would've been much more secure if I'd just stayed working,” says Dunne. “I'm not motivated by the money — hopefully I will have enough to live on.”

Starting late also means that one's career is likely to be foreshortened. Some may not make it to the tenure track; Hevey plans to spend six more years in graduate school before continuing his work by volunteering at the Botanic Garden.

Dunne is philosophical: “Realistically speaking, permanent positions are incredibly few and far between, so I don't necessarily have any expectations of getting a permanent post. I would be happy enough if I could postdoc until I come to the age that I retire.”

An academic career path isn't necessarily out of the question for older students, says Firestein, but he notes that industry might offer a quicker route to success. He's seen his past students rise quickly in that world.

The skills acquired during an earlier career can also confer an unexpected advantage. Oné Pagán wasn't ready for his first attempt at a PhD in Puerto Rico in his 20s. He left the programme after a year and worked as a middle- and high-school teacher — acquiring instructional experience that would serve him well later — and then as a research technician at a medical school. He decided to return to his studies and earned a master's degree at the age of 33. This led to a position teaching medical students.

Pagán still wanted to earn his PhD, but by then he was well into his 30s, with a wife and child. “I had a family, I needed to work — period,” he says.

Persistence should eventually pay off, even though it may take many years.

He found the right opportunity, however, when a collaborator of one of his former mentors invited him to apply to Cornell University in Ithaca, New York, for a PhD in pharmacology. Pagán and his wife talked it over and decided it was too good an opportunity to pass up. He qualified for student loans and a US National Institutes of Health scholarship that was meant to support university professors who wanted PhDs. It paid him 75% of his previous salary — not a lot, but enough. He enrolled at the age of 35, and this time, he was ready. “I was a responsible adult,” he says.

Still, he worried that as he climbed the academic ladder, his age might be a hindrance. He didn't want to do a postdoc and apply for tenure-track positions at 45. So he found five professor advertisements that didn't specifically seek postdoctoral experience. Only one, West Chester University in Pennsylvania, invited him to visit. After Pagán got the job, he asked his new colleagues what had made him stand out. It turned out to be the educational skills from his previous career, which shone in a teaching demonstration that was part of the interview process.

Family concerns

Family can certainly make it harder for scientists to move around, as the job typically requires, notes Pagán. For example, he has a sabbatical coming up, and he would love to take it in a lab in Europe. But with two kids and a dog, he's looking for options closer to home.

Family obligations were also a concern in the early career of David Gurwitz, a genomicist at Tel Aviv University in Israel. Owing to Israel's compulsory military service, and breaks between degrees that he spent earning money to support his growing family, Gurwitz finished his PhD at the age of 34 and his postdoc at 37, in 1989. He wanted his children to grow up in Israel near their grandparents, but faced a paucity of available academic positions. So he worked as a research associate instead, first at a government institute and then at Tel Aviv University.

Gurwitz organized collaborations and authored papers, and eventually was able to submit his own grant applications. He volunteered to teach courses, which attracted graduate students to his laboratory, although he had to co-mentor them with tenure-track professors. But a tenure-track post continued to elude him.

The tide turned in 2014 when Gurwitz won three major grants and his dean advised him to apply again for a tenure-track position. This year, at 65, he was hired as a tenured associate professor. “I believe this sets an Israeli record for age at first academic appointment,” says Gurwitz, who encourages others not to give up. “Persistence should eventually pay off,” he says, “even though it may take many years.”

Paul Bédard, a geological engineer at the University of Quebec in Chicoutimi, Canada, also had to bide his time for years before landing an academic position at age 50. No such jobs were available when he first tried in 1995 after a postdoc. So he spent five years working as a consultant for companies, and another decade as a lab manager at the university.

When a faculty position suddenly opened, Bédard was there to jump in. But he knew there was no time to waste. “You cannot say, OK, I'll take five years slowly to build,” says Bédard. “You get in on Monday, on Tuesday you have to be on a grant application, and on Friday have the money in.” Industry experience helped him to start at a sprint, he says, as did selecting a tight focus for his research.

And although a science career can be slow to start, or require a scary transition, there's reason for scientists who begin late to hope for the best. A 2015 study by the American Institute for Economic Research reported that 82% of those who attempted to change careers after age 45 were able to do so (see go.nature.com/2wzckct). They were also happier in their new jobs.

“It doesn't matter if you're going to start at 20 or at 40 or at 60,” says Pagán. “Just do it.”