BIOLOGICAL INSPIRATION FOR COMPUTING 287
biomolecular processes will be valuable. Already, commercial spinoff technologies are available: based
on Adleman’s research, a company in Japan developed a way to synthesize 10,000 DNA sequences to
rapidly search for the presence of genes related to cancer.^116 Also, biologist Laura Landweber’s research
into biomolecular computation at Princeton has provided insights for her research on DNA and RNA
mechanisms in living organisms. For example, her and Lila Kari’s analysis of the DNA manipulations
that occur in some protozoa is based on techniques of formal languages from computer science, show-
ing that the cellular operations performed by these protozoa are actually Turing-complete. The use of
formal computer science theory, in other words, has proven a useful tool for the analysis of natural
genetic processes.
8.4.2 Synthetic Biology
As a field of inquiry, the goal of biology—reductionist or otherwise—has been to catalog the diver-
sity of life and to understand how it came about and how it works. These goals emphasize the impor-
tance of observation and understanding. Synthetic biology, in contrast, is a new subfield of biology with
different intent: based on biological understanding, synthetic biology seeks to modify living systems
and create new ones.
Synthetic biology encompasses a wide variety of projects, definitions, and goals and thus is difficult
to define precisely. It usually involves the creation of novel biological functions, such as custom meta-
bolic or genetic networks, novel amino acids and proteins, and even entire cells. For example, a syn-
thetic biology project may seek to modify Escherichia coli to fluoresce in the presence of TNT, creating in
effect a new organism that can be used for human purposes.^117 In one sense, this is a mirror image of
natural selection: adding new features to lineages not through mutation and blind adaptation to an
environment, but through planned design and forethought. Synthetic biology shares some similarities
with recombinant genetic engineering, a common approach that involves transplanting a gene from one
organism into the genome of another. However, synthetic biology does not restrict itself to using actual
genes found in organisms; it considers the set of all possible genes. In effect, synthetic biology involves
writing DNA, not merely reading it.
One basic motivation of this field is that creating artificial cells, or introducing novel biological
functions, challenges our understanding of biology and requires significant new insight. In this view,
only by reproducing life can we demonstrate that we fully understand it; this is the ultimate acid test for
our theories of biology. It is precisely analogous to early synthetic chemistry: only by the successful
synthesis of a substance would a theory of its composition be verified.^118
More broadly, some synthetic biology researchers see created life as an opportunity to explore
wider conceptions of life beyond the examples provided by nature. For example, what are the physical
limitations of biological systems?^119 Are other self-replicating molecular information systems possible?
Are there general principles of biochemical organization? These inquires may help researchers to un-
derstand how life began on Earth, as well as the possibility of life in extraterrestrial environments.^120
Finally, synthetic biology has the potential to contribute significantly to technology, offering in
many ways a new industrial revolution. In this view, chemical synthesis, detection, and modification
could all be done by creating a microbe with the desired characteristics. This holds the promise of new
methods for energy production, environmental cleanup, pharmaceutical synthesis, pathogen detection
(^116) Business Week, “Len Adleman: Tapping DNA Power for Computers,” January 4, 2002.
(^117) L.L. Looger, M.W. Dwyer, J.J. Smith, and H.W. Hellinga, “Computational Design of Receptor and Sensor Proteins with
Novel Functions,” Nature 423(6936):185-190, 2003.
(^118) S.A. Benner, “Act Natural,” Nature 421:118, 2003.
(^119) D. Endy, quoted in L. Clark, “Writing DNA: First Synthetic Biology Conference Held at MIT,” available at http://
web.mit.edu/be/news/synth_bio.htm.
(^120) J.W. Szostak, D.P. Bartel, and P.L. Luisi, “Synthesizing Life,” Nature 409(6818):387-390, 2001.