Biology Reference
In-Depth Information
lifetime; after a while they malfunction and have to be either repaired or replaced
in order for the factory to outlive the lifetimes of its machines. Let C in Fig. 4a
malfunction. As shown in Fig. 4b, one possibility for overcoming this problem
would be to expand the scope of the factory by acquiring a new fabricator
D that builds replacement C from material X (or repairs C using spare parts X).
It is clear that we have now started to create a 'fabrication hierarchy' in that
C, which acts as fabricator for the lower transformation level, now also is the
target of a fabrication process at a higher level. Furthermore, in this expanded
description the factory is less autonomous in that it now depends on not only an
external supply of A but also of X. What if the supplier of X becomes unreliable?
The most effective measure to counter this would be to incorporate additional
machinery C
X
that can fabricate X from A into the factory, alongside the original
machinery that fabricates B (now distinguished as C
B
), thereby increasing the
degree of autonomy of the factory at the expense of more machinery (Fig. 4c).
However, there is a problem in Fig. 4c. D is required not only to fabricate
C
B
from X, but apparently also C
X
from something. But from what? We could
consider new material Y, but in order to become independent of a possibly
unreliable supply of Y that would mean incorporating into the factory even
more new machinery C
Y
to fabricate Y from A. An infinite regress looms. This
regress can be sidestepped by ensuring that both C
B
and C
X
can be fabricated
by D from X (in which case Fig. 4c would be a valid diagram). Furthermore,
nothing now prevents us from discarding C
B
, so forcing the factory to become
a producer of primarily C
X
instead of B, X now being an intermediate in the
process (Fig. 4d). When, further on, we analyse the living cell as we know
it in terms of its fabrication hierarchy, we shall see that it has adopted both
these strategies. Now that we understand the subtleties involved we shall, in the
interest of readability, continue to use the diagram in Fig. 4e.
Just as C, fabricator D is also subject to failure and we can imagine safe-
guarding the factory (so increasing its relative independence even further) by
adding another level to the fabrication hierarchy in which D is fabricated by
a new fabricator E from either C (Fig. 5a) or B (Fig. 5b). As before, adding
this level to the fabrication hierarchy makes all the lower levels more compli-
cated in that new machines must be fabricated as needed. However, and this
is important, the factory still depends on a supply of its input A and the one
fabricator, here E, that is not manufactured inside the factory. In fact, as the
proportion of endogenously produced fabricators to external fabricator increases
A
C
E
A
C
E
(a)
(b)
B
D
B
D
Figure 5
Adding another level to the fabrication hierarchy.
