Biology Reference
In-Depth Information
But what then did we learn from this topic? And how can all the aspects
discussed be brought into a single, perhaps multidimensional, perspective?
Below we shall highlight what we learnt from the perspective of the scientific
revolution in biology leading to the new paradigm, systems biology.
1. SYSTEMS BIOLOGY IS FUNCTIONAL AND MECHANISTIC
RATHER THAN EVOLUTIONARY BIOLOGY
Systems biology, especially bottom-up systems biology, puts a strong emphasis
on biological function, even though it starts somewhat indifferently from the
molecules that do not function themselves. Molecular biology sometimes uses the
word function for an activity catalyzed by an individual macromolecule outside
the context of the living organism. Only when the context of the whole organism
is added, the word function can relate to fitness and become a component in a
legitimate teleological explanation. We note that systems biology is still remote
from this, because it is often unclear what the true habitat of the organisms
harboring the molecule under study has been and what has been or is important
for its fitness. Yet, there are well-known activities in this direction, such as
flux-balance analysis (Price et al., 2004).
It is important to realize that systems biology tries to understand life as it
is now, while it does not focus on evolutionary biology. It may use reasoning
derived from evolutionary biology, such as reasoning based on homologies,
but it does not yet aim at explaining the evolution of biological systems.
This preference reflects the conviction that life should be understandable
without reference to the histories of all life forms. Systems biology aims at
acquiring a molecular mechanistic understanding of biological systems subject
to challenges to their existence from the outside world. For systems biology, the
properties of molecules are considered as important as the systemic behavior,
and understanding is considered to have been achieved when it can be shown
how the latter emerges from the former when their nonlinear interactions and
arrangements are taken into account. Because of the complicated organization of
cells and nonlinearity, hence condition dependence of the interactions, detailed
models are required to 'calculate the emergence of life from its dead molecular
constitution'. According to Mayr's analysis of biology in terms of functional
and evolutionary biology (Mayr, 1961), where the former would be dealing
with how-questions and the latter with why-questions, systems biology deals
with the former.
This is not to say that there will be no bridge between systems biology and
evolutionary biology (Wimsatt, this volume). Typically, once it is understood
why a system is capable of living, one may also begin to note that other
constellations of molecules or atoms could also be alive. An example is life
