Skip to main content

Luis Nunes Amaral's world of networks

AAAS Fellow Luis Nunes Amaral studies complex systems, how relationships between parts give rise to the collective behaviors of a system and how the system interacts and forms relationships with its environment. (Photo: James Kegley)

Physicist Luis Nunes Amaral thinks nothing of jumping the fence from his own field to work in others—biology, engineering, and computer science, to name a few.

"Throughout my career, people have told me to focus," he says, adding, "Recently, though, they have stopped."

The critics may have backed off because Amaral, professor of chemical and biological engineering at Northwestern University, associate professor of medicine at NU's Feinberg School of Medicine, and an AAAS fellow, is clearly doing something right. In 2012, he was one of 50 researchers the Howard Hughes Medical Institute, based in Chevy Chase, Maryland, chosen for an Early Career Scientist award that included a research budget of $1.5 million. That honor came on the heels of a 2006 $1 million W. M. Keck Foundation grant.

Amaral says he was lucky to have received those honors, that they saved his lab and gave him money for research he might never have received from other sources, given his "good but weird" resume. Still, his work is as arresting as it is varied.

Amaral's lab at NU, in Evanston, Illinois, has recently investigated the possibility that an optimal level of stress exists for humans; the role airport hubs might have played in the spread of the SARS virus in 2003; and whether women in science, technology, engineering, and mathematics at research universities might not publish as often as men—a common criticism of women in academia—because their labs don't receive the same level of support from their institutions in the first place as their male counterparts', a shortfall that is bound to make publishing more difficult.

Two keys to Amaral's wide-ranging work are computers, and the relatively new study of complex networks, systems with a large number of components that interact in ways that are not always obvious. Transportation systems, food webs, Facebook, and genomes can all be reduced to component parts—to individual genes, friends, consumers, or airports—and the activity that transpires among them. All are complex systems, all organize themselves without direction from a central authority, and they share some basic common architecture.

"Thinking of the world in terms of networks has become a keystone idea for many scientists," Amaral says. "The idea is [networks] are mathematical objects" that can offer insights with wide applications—wherever "complex networks of interactions are present," that is.

While he is interested in a great many things, "I'm always thinking about concrete systems for which I can find some data," says Amaral. It's why he chose hard science over any of the softer fields that appealed to him as well. "It's good to have some more objective way of supporting your point of view than just [being the person] who can talk longer or louder."

In the recent past, experimental techniques for any scientific field tended to be highly specialized. Now, though, "computers have made a revolutionary change in how we do science. If you are using paper and pencil, then you need incredibly deep knowledge of [the specific mathematical techniques required by your subject area]... but computers let you use the same techniques in many different contexts. You can develop models and test them without being forced to specialize."

A researcher might want to collaborate with someone who has that deep knowledge, though. "If we work together, maybe we can do something that will push the field in new directions," Amaral says.

A recent focus of Amaral's work is no less than the commonalities of all living things at the cellular level. His lab's recent research indicates, for example, that only about 10% of  the thousands of molecules in any organism's cellular metabolism play a critical role in metabolic processes, connecting organism-specific molecules and reactions, and anchoring the metabolism. These "connector" molecules appear to occur in nearly all living organisms, and to perform identical functions across the board.

Amaral wants to create an online, interactive "atlas" of cellular metabolism that will pinpoint the positions of these commonly shared connector molecules in different organisms. He hopes this atlas will allow researchers to get down into biological systems in an unprecedented way, and perhaps to tinker with them as well.

This work can provide "enormous insight...into how metabolism is organized and what components are important," Amaral writes.

The son of a factory worker in Lisbon, Portugal, growing up in the years when that country was beginning to brighten after decades of repressive government, Amaral found his way to science through a book about various professions a neighbor loaned him. "Scientist" sounded like the career for him, Amaral recalls, and he never wavered from that idea, even when school officials tried to steer him toward becoming an electrician instead.

As a boy, he loved Carl Sagan's "Cosmos" television series. As a graduate student in Lisbon, he discovered James Gleick's Chaos, a narrative-nonfiction account of the development of chaos theory. "I was like, 'Wow! This is the coolest thing ever!'" Amaral recalls.

"I worked with some of the people mentioned in that book for my Ph.D.," at Eugene Stanley's lab at Boston University, "an amazing place where people were able to do collaborative research in many different areas," Amaral says.

Collaboration has definitely been a theme in Amaral's career, and he is presently the co-director of the Northwestern Institute on Complex Systems, co-administered by NU's Kellogg School of Management and the Robert R. McCormick School of Engineering and Applied Science. NICO is extending research on complex networks into social studies and business.

"It's rare to have the degree of collaboration between the engineering school and the management school that we have here at Northwestern," Amaral says.

NICO co-director Brian Uzzi, a Kellogg professor, says of Amaral, "In thinking about the different possibilities for attacking important problems, where most people will have one idea, he'll have five ideas—and they're all really good."