If the 20th century belonged to physics, the 21st century may well belong to biology. Just 50 years after the discovery of DNA's chemical structure and the invention of the computer experiment, a revolution is occurring in biology, driven by mathematical and computational science. An explosion of research is reshaping fields such as mathematical ecology, epidemiology, genetics, immunology, neurobiology, and physiology, to give just a few examples.

Today, a biology department or research medical school without "theoreticians" is almost unthinkable. Biology departments at research universities and medical schools routinely carry out interdisciplinary projects that involve computer scientists, mathematicians, physicists, statisticians, and computational scientists. And mathematics departments frequently engage professors whose main expertise is in the analysis of biological problems.

In recent years, federal and private agencies have markedly increased funding for research innovation at the math-biology interface. In the U.S., fellowship programs and career awards funded by NIH, NSF, DOE, EPA, and other federal agencies, as well as by private philanthropies such as the Burroughs Wellcome Fund (which also supports Science's Next Wave), have begun to alter the scientific training landscape. Interdisciplinary and multi-agency initiatives, such as NSF's IGERT and a new partnership between NIH and NSF, promise to advance biology through the use of modeling and quantitative methods.

Funding organizations outside the U.S. are similarly active in expanding opportunities for mathematical biology training and research. International events, the changing political landscape, and emerging public health trends worldwide are helping push research in mathematical and quantitative biology around the world. Globalization has made the concept of borders obsolete, and as economic interdependence among nations becomes the norm, the problems of one country become problems for the whole world. Last year, the SARS epidemic spread almost simultaneously in China, Hong Kong, Vietnam, Taiwan, and Canada. In addition, the events of 11 September have made plausible the deliberate release of biological agents, and the consequences of such an action would respect no borders. These global scientific problems require a global, multidisciplinary scientific workforce. Sociologists, biologists, economists, policy experts, and mathematicians must work hand in hand on issues such as foot-and-mouth disease, "mad cow" disease, and the development of sensors capable of detecting and identifying specific biological agents.

These exciting research and training opportunities are attracting talented young scientists who are willing to work to bring together the disparate disciplines and cultures of the biological and mathematical sciences and, in the process, to forge completely new areas of research, new ways of thinking, and new kinds of scientific careers.

Mathematical and Theoretical Biology - A European Perspective
Andreas Deutsch, head of the Methods of Innovative Computing programme at the Technical University in Dresden, gives an overview of mathematical and theoretical biology in Europe, and discusses the role of the European Society for Mathematical Biology.

One Person's Path to Mathematical Biology
A one-off attempt by David Earn to apply game theory to a biological question sparked an entirely different career leading to his current work at Ontario's McMaster University.

Job Opportunities in Mathematical Biology
Though mathematical biology is still mainly an academic phenomenon, Jim Kling says some jobs already exist in the private sector, and more are likely to follow.

Balancing the Scrutable and the Inscrutable
Mathematics provides inroads to almost any scientific discipline, notes Ben Goertzel, chief scientific officer of the life-sciences company BioMind. His own career is a good example.

Discovering Potentials and Possibilities
Frithjof Lutscher, a postdoc from Germany at the University of Alberta, talks about his former insecurities about making it in a mathematical field and why he likes the academic environment in North America.

Adding to the Sum of Biological Knowledge
Population biologist Mike Bonsall offers tips for those who, like him, have a biological training and want to develop their mathematical skills in order to enhance their research.

The View from IPAM
Mark Green, the director of UCLA's Institute for Pure and Applied Mathematics (IPAM) says this interdisciplinary field needs practitioners that can speak each other's language.

Mathematical Biology at Arizona State
Carlos Castillo-Chavez explains that no single path can meet all needs, so Arizona State offers a wide range of training options.

Nature or Nurture? My Mathematical Biology Upbringing
Leah Edelstein-Keshet describes her journey to a career in mathematical biology in Canada, and how the combination of disciplines promotes interesting, and varied and new research every day.

Using Nature's Ideas to Solve Our Problems
If mathematics are often used at the service of biology, it can work the other way, too, as Uwe Aickelin explains.

Mathematical Biology: An Evolving Discipline and Career Over 15 Years
Thomas Hillen at University of Alberta describes a professional and geographical journey that has ended, for now, in Canada.

Integrating Mathematics and Biology in Exercise Sciences
Even though he's not a mathematician, Harry Rossiter finds his experience within an interdisciplinary team greatly enhanced by the integration of mathematics and biology within exercise sciences.

Supporting Research at the Scientific Interface
The Burroughs Wellcome Fund's Career Awards at the Scientific Interface (CASI) foster the early career development of researchers with backgrounds in the physical and computational sciences who intend to work on biological questions.

The Mathematical Biosciences Institute
According to Tony Nance and Avner Friedman, Ohio State's interdisciplinary Mathematical Biosciences Institute aims to foster interaction between the two disciplines, and to nurture an international community of researchers.

Biology Outside the Box
Mathematical and computer methods keeps Mark Lewis and colleagues well rounded as they research fundamental biological and health care questions at the University of Alberta's Centre for Mathematical Biology.

Seeing the Forest for the Trees
Mathematical biology helps explain the big picture for Howard University's Abdul-Aziz Yakubu, who models endangered species and the spread of epidemics while passing this big-picture passion on to his students.

Biologist Seeks Understanding Mathematician
Elisabeth Pain describes how young mathematicians with an understanding of biology and good communication skills have many opportunities opening to them, such as a new Institute for Mathematical Sciences at Imperial College.

Career Automata
With his catholic interests and applied orientation, the University of Maine's David Hiebeler, an assistant professor in the mathematics department, is typical of a new generation of talented mathematical scientists.

Mathematics, Computation, and Epidemiology
Computational and mathematical epidemiology offers new and stimulating training and career opportunities, many of which are available at Rutgers' Center for Discrete Mathematics and Theoretical Computer Science (DIMACS), notes Rutgers professor Fred Roberts.

Been There, Done That, Learned Some Lessons
Mathematical biology may be exploding, but it's hardly a new kid on the block. Bernouli, after all, designed the first epidemiological models in 1760 and, write Lou Gross and Tom Hallam, the University of Tennessee, Knoxville's program in mathematical ecology has been around for more than a quarter-century.

Mathematics, Epidemics, and Homeland Security
Today's complex world of viral infections and threats to national security requires an interdisciplinary approach using mathematics. Carlos Castillo-Chavez explains the role for mathematical biologists. ( Also available in Spanish)

Jim Austin is the editor of Science Careers. @SciCareerEditor on Twitter