Environmental Engineering Reference
In-Depth Information
Modelling as Derived from Physics: Ecology as Derived
from Natural History
Physics had the role of the paradigmatic, standard-setting science. The establish-
ment of the experimental method as a primary source of rational intelligence was
established first for physical relations. Galilei and successors emphasized that a
temporally limited experiment, well isolated from the context and carefully
arranged, can stand as a prototype for a class of similar phenomena. Knowing
one outcome informs about the entire field of identical settings. One case can stand
for all - as long as standardization is adequate. This applied to inorganic material,
i.e.
res extensa
, as Descartes put it. He exempted
res cogitans
, the domain of
intelligence, where mechanistic paradigms would not hold in his opinion. Living
beings - though usually considered as plain
res extensa
- posed difficulties to some
degree. Discussions sparked about how far man and animals share certain proper-
ties, and how the human mind as a domain of free choice and brain as a domain of
its physical substrate would relate. In neurology and brain research certain aspects
of this controversy continue today (Maasen et al. 2003).
Studying the diversity of life and life forms was the domain of natural history
(Mayr 1982). An early impetus of natural history was a theological interest to
illustrate the richness of creation (natural theology, e.g. Paley 1803). Natural
history was largely descriptive and quantification played a relatively marginal
role. This line of tradition was influential in ecology. It remained meaningful and
it caused scepticism towards quantitative “physicalistic” descriptions. The founder
of ecology, Ernst Haeckel himself, did not emphasize the application of quantitative
methods in ecology. He largely used conceptual approaches, verbal descriptions,
and graphical representations. The initiative to look at quantitative relations of man
and environment did not emerge in the context of natural history or ecology but in
physics, in economics, and demography.
Malthus: Basic Ideas in Population Science
Robert Malthus (1766-1834) was one of the first to introduce quantitative con-
siderations in the population context. He considered implications and determinants
of the growth of human populations. Mainly operating from an economic perspec-
tive, his ideas had subsequent influence for ecological considerations. He linked the
growth and well-being of the human population directly with a development of
natural resources (Malthus 1798) (Fig.
3.1
).
Later, Darwin (1809-1882) considered the malthusian ideas in his develop-
ment of evolutionary theory. A key idea of Malthus was that population growth
tends to exhibit self-similar characteristics: If each of the population member has
the same chances of fertility in space and time, the involved growth processes tend
to be exponential. With a constant rate of increase, exponential growth accelerates
