The Digital Human
Simulation tools that reproduce the operation of complex systems in computer software are becoming essential for understanding systems ranging from aircraft engines to hurricanes. Flight simulators and other simulation-based tools have become invaluable learning tools. The digital human is a project to create a software simulation of the most complex system known: the human body. It will use 21st century information technology tools to represent the body’s operation from the level of the molecules that form DNA and proteins, cells, tissues, organs like the heart and lung, and the entire body*.
The Digital human can be a powerful research tool, allowing scientists to tie together the explosion of information available about biological systems. Now that the human genome has been sequenced, the rate of discovery is likely to increase. These simulations provide a powerful tool for understanding the connection between thousands of simultaneous processes that occur when a cell is attacked by a virus or bacteria and the way drugs might help counter the attack. They could help understand how performance of the heart is affected by defects in its blood supply and anticipate the benefits of different interventions. By providing clear, visual representations of the body’s processes, and allowing open opportunities for explorations, these simulations can also provide a key learning tool useful for students at many different levels – including training for professionals already in the field. Thus, simulation can be used to train physicians and a healthcare personnel as it has been used in flight training. It would allow, for instance, surgeons and surgical teams to develop and practice procedures using data from individual patients prior to an actual operation on the patient. It can also help designers of cars, aircraft – even spacecraft -- design safer vehicles using simulated human surrogates.
The Digital Human project will (i) build a community of researchers working on simulating the human body (and its components) making it possible for them to share and reuse components without legal complexities (defining the terms for “open source” software), and (ii) develop a series of standards allowing components built by different groups and individuals to plug together and be reused. NIH and other agencies are already building simulations of the heart, lungs, cells and other systems. These investments will undoubtedly increase rapidly since experimental data capable of supporting complex simulations is now available and advances in information science make it possible to consider a major effort. Unfortunately most simulations today are built from scratch by independent groups – there is no ability to share components so that different pieces will fit together. This means, for example, that someone building a simulation of a heart can not take advantage of a simulated heart valve built by another group. The Digital Human is far too ambitious for any group or individual to undertake. It must be built by a large community able to share and review each other’s work. Modern software tools make this feasible.
While immediate results can be expected from simulations already being sponsored by the NIH and other agencies, it is likely that a compete first draft of the Digital Human will require ten years and over a billion dollars.