Lamarckism And Neo-lamarckism
The "Lamarckian" view as opposed to the Darwinian continues to hold its
own, and indeed is more ardently supported than ever. On this view,
evolution has been accomplished not by a laborious selection of the best
which chanced to present itself--a selection in relation to which organisms
remained passive, but rather through the exertions of the organisms
themselves. It has been especially through the use and exercise of the
<
r />
various organs in response to the requirements of life, through the
increased exercise of physical and mental functions, that the organism has
adapted itself more diversely and more fully to the conditions of its
life. What one generation acquired in differentiation of structure, in
capacities and habits, through its own exertions, it handed on to the
next. By cumulative inheritance there ultimately arose the fixed specific
characters, and the diversity and progressive gradations of organisms have
gone hand in hand with an ever increasing activity. And as with the
physical so it has been with the mental. Through continual use and
exercise of the functions their capacity has been increased and modified.
Through the frequent repetition of voluntary actions necessary to life the
habitual use of them has come about. Habits that have become fixed are
correlated with habitual psychical predispositions. These, gradually
handed on by inheritance to the descendants, have resulted in the
marvellous instincts of animals. Instinct is inherited habit that has
become fixed. Corresponding to this there is on the other hand the
recognition--in theory at least--that the disuse of an organ, the
non-exercising of a function leads to degeneration of structure and so
co-operates in bringing about a gradual but persistent modification of the
features and constitution of organisms.
These views, which have grown out of Lamarck's fundamental ideas
("Philosophie zoologique," 1809) are now usually associated with the
theory advanced chiefly by Etienne Geoffrey St. Hilaire ("Philosophie
zoologique," 1830), the opponent of Cuvier, and the ally of Goethe, of the
direct influence of the monde ambiant. The "surrounding world," the
influences of climate, of locality, of the weather, of nutrition, of
temperature, of the salinity of the water, of the moisture in the air, and
all other conditions of existence, influence the living organism. And they
do so not indirectly, as is implied in the process of selection, simply
playing the part of a sieve, and not themselves moulding and transforming,
but directly by necessitating the production of new developments in the
living substance, new chemical and physiological activities, new groupings
and changes of form, and new organs.
Darwin himself did not regard these two theories as opposed to the theory
of selection, but utilised them as subsidiary interpretations. It is
obvious, however, that at bottom they conceal an essentially different
fundamental idea, which, if followed out to its logical consequences,
reduces the "struggle for existence" to at most a wholly indifferent
accessory circumstance. Weismann felt this, and hence his entirely
consistent endeavours to show by great examples, such as the origin of
flowers, the mutual adaptations of flowers and insects, the phenomena of
mimicry, and many other cases, that neither the Lamarckian nor any other
factor in evolution, except only natural, passive selection, suffices as
an interpretation. From the Darwinian standpoint he is absolutely right,
and must needs speak of the "omnipotence of natural selection," for it
must either be omnipotent, or it must give place to the other two factors,
and retain only the significance we attributed to it in another connection
(p. 157), which amounts to saying none at all. It is obvious enough why
the discussion as to these factors should centre round the question of the
"inheritance of acquired characters," "acquired" either through the use or
disuse of organs, the exercise or non-exercise of functions, or through
the stimuli of the external world.
The neo-Lamarckian conflict with Darwinism has become more and more acute
in recent times, and the neo-Lamarckians have sometimes passed from
contrasting rival interpretations to excluding the Darwinian factor
altogether. As the particular champion of the neo-Lamarckian view, we must
name Th. Eimer, the recently deceased Tuebingen zoologist. His chief work
is in three volumes, entitled "Die Entstehung der Arten auf Grund von
Vererbung erworbener Eigenschaften, nach Gesetzen organischen
Wachsens."(43) It is a polemic against Weismannism in all details, even to
the theory of "germinal selection." Eimer follows in the footsteps of St.
Hilaire, and shows what a relatively plastic and sensitive creature the
organism is to the surrounding world, the conditions of nutrition and
other such influences. There is in this connection a particularly
instructive chapter on the physiological and other variations brought
about by external influences which act as "stimuli of the nervous system."
The whole theory of Lamarck and St. Hilaire transcends--notwithstanding the
protests of Eimer to the contrary--the categories of the mechanical theory
of life, and this chapter does so in particular. The array of facts here
marshalled as to the spontaneous self-adaptation of organisms to their
environment--in relation to colour mainly--forms the most thoroughgoing
refutation of Darwinism that it is possible to imagine. It is shown, too,
by a wealth of examples from osteology, how use (and the necessities of
the case--a consideration which again goes beyond the bounds of mere
Lamarckism) may modify, increase or diminish vertebrae, ribs, skull and
limbs, in short, the whole skeleton.
Kassowitz is equally keen and convinced in his opposition to natural
selection, and in his comprehensive "Allgemeine Biologic"(44) he attacks
orthodox Darwinism from the neo-Lamarckian standpoint. The whole of the
first volume is almost chapter for chapter a critical analysis, and the
polemical element rather outweighs his positive personal contribution. He
criticises very severely all attempts to carry the Darwinian principle of
explaining adaptations into internal and minute details, arguing against
Roux's "Struggle of Parts" and Weismann's "Germinal Selection." And though
he himself maintains very decidedly that the ultimate aim of biology is to
find a mechanical solution of the problem of life, he criticises the
modern hypotheses in this direction without prejudice, and declares them
unsuccessful and insufficient, inclining himself towards the
"neo-vitalistic reaction" in its most recent expression. Along with Eimer
and Kassowitz, we may name W. Haacke, especially in relation to his views
on the acquisition and transmission of functional modifications and his
thoroughgoing denial of Darwinism proper. But his work must be dealt with
later in a different connection.(45)
These neo-Lamarckian views give us a picture of the evolution of the world
that is much more convincing than the strictly Darwinian one. Instead of
passive and essentially unintelligent "adaptation" through the sieve of
selection, we have here direct self-adaptation of organisms to the
conditions of their existence, through their own continual restless
activity and exertion, an ascent of their own accord to ever greater
heights and perfections. A theory of this kind might easily form part of a
religious conception of the world. We might think of the world with
primitive tendencies and capacities, in which the potentialities of its
evolution were implied, and so ordered that it had to struggle by its own
exertions to achieve the full realisation of its possibilities, to attain
to ever higher--up to the highest--forms of Being. The process of nature
would thus be the direct anticipation of what occurs in the history of man
and of mind. And the task set to the freedom of individual men, and to
mankind as a whole, namely, to work out their own nature through their own
labour and exertion, and to ascend to perfection--this deepest meaning of
all individual and collective existence--would have its exact prelude and
preparation in the general nature and evolution of all living creatures.
The transition from these theories of nature to a teleological outlook
from the highest and most human point of view is so obvious as to be
almost unavoidable. And although a natural science which keeps to its own
business and within its own boundaries has certainly no right to make this
transition for itself, it has still less right to prevent its being made
outside of its limits.