Like most children of the 1980s, I grew up with a certain scientist as a role model. His home was packed with expensive equipment, his eyes were as wild as his white hair, and he invented a device that took him nearly 30 years to perfect: the flux capacitor.

Yes, Dr. Emmett "Doc" Brown from Back to the Future was the quintessential scientist—a bit kooky, a bit oblivious, and a bit brilliant. But what sort of scientist was he?

That question came up in Back to the Future Part III. Finally, after years of wondering whether Doc Brown was a physicist (time travel) or a neurologist (failed mind-reading device) or an astronomer (named his 1955 puppy Copernicus), we'd know the truth. "Actually," he told Clara Clayton, "I'm a student of all sciences."

What?

Can you be that?

Can you really be a student of all sciences? Can you get a Ph.D. in "All Sciences"? Can you get tenure at a university without joining any particular department? Can you conduct experiments in geology, quantum physics, and nutrition all at the same time?

The answer, of course, is "no." You can't just be a scientist. It's a nice dream, that a scientist could be equally conversant in all branches of science. But it turns out—brace yourself—that Back to the Future Part III was anachronistic. You can be a biologist, or a chemist, or an astronomer, but you can't focus on "all sciences."

And, in fact, you can't just be a biologist. You have to be a population biologist, a botanist, an ecologist, a biophysicist, a biochemist, a microbiologist, a molecular biologist, a bioengineer, a geneticist, an evolutionary biologist, a developmental biologist, a zoologist, an anatomist, a pathologist, a virologist, an ichthyologist, a herpetologist, an ornithologist, a paleontologist, an exobiologist, or you-get-the-gist.

Then, within your sub-subfield, you have to choose one hyperspecific branch of study. A herpetologist could take years to explore the complexity of Santa Cruz long-toed salamander nostrils. An anatomist could spend 10 hours every day thinking about just one or two specific parts of the human reproductive system—goodness knows I have.

I once rotated in a lab whose principal investigator has spent more than 50 years examining a single protein in the pathway that allows bacteria to metabolize a sugar called arabinose. Fifty years.

In what other profession is myopia such a virtue? A car salesperson sells cars. He or she doesn't spend a career solely focused on the screws that secure the cup holders on a 1992 Pontiac Sunbird.

Even worse, as Doc Brown's nonsensical answer in Back to the Future Part III suggests, the public doesn't fully understand the narrowness of our focus. During the 2004 cicada emergence in Baltimore, one of the administrators in my graduate biology department told me she was fielding phone calls daily from people with questions about cicadas. She had to tell the callers, "Sorry, I know we're a biology department with dozens of faculty members and hundreds of students and employees, but no one here is an entomologist. We know as much about cicadas as you do. Now, if you have any questions about the bacterial arabinose operon, we've got your guy."

There are, of course, good reasons for hyperspecificity. Scientific problems are complicated and don't give up their answers easily, so it takes intense focus to solve one. Also, there are so many scientists in the world that if you don't choose your niche, you become uncategorizable and therefore unemployable.

UNIVERSITY HIRING COMMITTEE: So, what has your research focused on?
YOU:  Everything! Everything everything everything! The whole universe! I study it all! It's all so beautiful!
UNIVERSITY HIRING COMMITTEE:  We're not reimbursing your plane fare.

Still, wouldn't it be fun to go solve a problem in another field once in a while? I work on a malaria vaccine, and that's what I do every day. That is, as scientists say, my "main thingy." But I have fantasies of crouching in a forest, observing wildlife. Or trekking to Antarctica to collect ice core samples. Or gathering data from a giant telescope. Or participating in one of those solar car races. If I showed up at one of those, however, the only way they'd accept my help is if someone said, "Oh no!  One of our solar cars has malaria!" Even then I couldn't cure it, per se, because I'm not a parasitologist. (And because, you know, cars don't get malaria.)

In theory, if you really want to, you can switch your career to a different track. It certainly happens, and it usually makes your colleagues shake their heads and say, "Poor Liam. He was learning so much about salamander nostrils, but I guess his passion was really in high-energy muon collisions." They say this regardless of whether your name is actually Liam, which is weird, though still probably not the weirdest thing about people who study salamander nostrils.

But even if you switch successfully, that's just finding a new microfocus, not generalizing. That still doesn't make you a practitioner of "all sciences."


CREDIT: Hal Mayforth
Click the image to enlarge

I didn't know, growing up, that all scientists specialize. Did you? No one ever took me aside and said, "You know that sense of wonder that we've been cultivating in you about every aspect of the natural world? Well, if you could just do us a favor and direct it toward one tiny thing for the rest of your life, that would be great. Also, the Tooth Fairy is dad, red M&M's cause cancer, and your hermit crabs died of heartbreak."

Now that I do know about specialization, it's honestly kind of a bummer. I like my research. But I'll never get to work on "all sciences."

Then again, maybe I'm not listening to Doc Brown's whole statement. He didn't say he worked on "all sciences"—he said he was "a student of all sciences." To be a student, you just need to want to learn about something, and there's no limit to the number of things you can want to learn. Doc Brown wasn't saying that he was a generalist. He was saying that he was receptive and curious. (He was also trying to get into Clayton's bloomers, so perhaps he was exaggerating his prowess.)

Although we do need to choose a field of interest, we can be curious about anything we want—and it's this curiosity, the motivation to answer as many different questions as possible, that matters most. By wondering about other fields, even if we don't have time (or funding) to explore them, we don't just satisfy a nagging despair about the necessity of choice. We broaden the way we think about all scientific problems. We become better scientists.

So there may not be time to cram several full science careers into your life—let alone all scientific careers—but there's always time to study new fields that interest you. There's always time to wonder, and there's always time to learn. Especially if you've built a time machine.

Adam Ruben, Ph.D., is a practicing scientist and the author of Surviving Your Stupid, Stupid Decision to Go to Grad School.

10.1126/science.caredit.a1300151