Where does innovation come from? How can it best be nurtured and encouraged? These questions are taking on global significance as fast-developing nations such as China, India and Brazil increasingly see leadership in innovation as key to their economic competitiveness. Although the link between innovation and economic strength is a matter for debate, the power of innovation to shape and transform society makes it worth studying. Earlier this summer, Nature began a monthly series of Commentaries to explore the origins of innovation and how it can be nurtured (see http://www.nature.com/nature/focus/innovation).

One common theme in the series is that the standard, linear model of innovation is too simplistic. That model, extant since at least the 1940s, posits that new ideas and technologies originate in the nursery of basic research. And, like growing children moving through school and university to full-time employment, these innovations progress through applied research to development and, finally, to the marketplace.

Scientists and engineers often feel hamstrung by the impositions of policy and regulation.

This linear sequence contains an element of truth. But it misses the fact that many innovative ideas come the other direction: from users, consumers and efforts to solve practical problems. The linear model also tends to overstate the contribution that basic research makes to the final outcome, by neglecting the roles played by design, manufacturing and business processes. And the model tends to give policy-makers the impression that innovation is considerably more predictable and controllable than it actually is.

A more accurate picture is that of a nonlinear 'ecosystem', in which innovation is driven by multiple players, forces and feedback loops working simultaneously. Such an ecosystem cannot be managed — at least, not in the conventional sense of top-down control. But it can be cultivated, in the way that a gardener can try to create the right conditions for plants to grow, while accepting that unforeseen elements ultimately dictate the outcome.

Such unpredictability is discussed on page 940 by David Guston, co-director of the Consortium for Science, Policy and Outcomes at Arizona State University in Tempe. The disruptive force of innovations, such as those edging their way towards fruition in stem-cell therapy, often seems at odds with a public policy that must consider the societal impacts of innovation and the social mores of the times. Scientists and engineers often feel hamstrung by the impositions of policy and regulation. Nevertheless, policies that nurture and guide innovation in socially acceptable frameworks could vastly increase public support and understanding of research goals.

The unpredictable nature of innovation means that this investment may not always turn out as expected. But with careful forethought, policy can usefully prepare the soil. This series of Commentaries will continue to explore the origin and nature of innovation — and, we hope, will provide powerful new ideas for culturing its growth.