Biology Reference
In-Depth Information
These properties cannot be compared with those of a simple
machine. How can we account for this? The laws of physics and
chemistry and mechanistic determinism are not sufficient to do so,
in Driesch's opinion, and he evokes the action of a vital force that
he calls 'entelechy' (Driesch, 1908, 1914), but such an explanation
is obviously not acceptable to us. We do have to acknowledge how-
ever that giving prominence to cellular plasticity is still relevant
and the issues raised by Driesch are still topical. They are, indeed,
similar to those posed by the non-specificity of proteins. In both
cases the potential for differentiation of the cells, or for interaction
between molecules, is greater observed
ex vivo
than
in vivo.
Without
adopting Driesch's vitalism, it is necessary to take this into account
when explaining ontogenesis.
5.3.2
The neo-vitalistic holism of Walter Elsasser
Molecular biology has been influenced by the work of Delbrück and
Schrödinger, while another physicist, Walter Elsasser (1904-1991),
was also interested in biology, but from a completely different point
of view, for he put forward a vitalistic conception (Elsasser, 1998).
According to Elsasser, the living organism is so complex that it can-
not be analysed with the laws of physics and chemistry. He based
his proposition on a number of arguments. If the 10
12
atoms of a
cell were solely controlled by the laws of physics it would be possi-
ble to calculate how many combinations of them would be possible.
This number is greater than 10
100
, i.e. far greater than the number
of protons in the universe, namely 10
80
. There is no corresponding
physical reality or operational value. One can also calculate the
total number of a given type of cells that exist or have existed in
the history of the Earth. This is in the order of 10
42
. The number
of possible molecular states is therefore hugely in excess of the num-
ber of cells actually existing. On account of this it might reasonably
be thought that the living organism is highly undetermined at
molecular level. Elsasser started from this hypothesis for his theoreti-
cal elaboration. Initially, he acknowledged that it cannot be proved
immediately, but only its plausibility progressively demonstrated.
