Dr Robert A. Hatch - University of Florida
Lamarck & Evolution
In every animal which has not passed the limit of its development, a more frequent and continuous use of any organ gradually strengthens, develops and enlarges that organ, and gives it a power proportional to the length of time it has been so used; while the permanent disuse of any organ imperceptibly weakens and detgeriorates it, and progressively diminishes its functional capacity, until it finally disappears. All the acquisitions or losses wrought by nature by nature on individuals, through the influence of the environment in which their race has long been placed, and hence throught the influence of the predominant use or permanent disuse of any organ; all these are preserved by reproduction to the new individuals which arise, provided that the acquired modifications are common to both sexes, or at least to the individuals which produce young. Philosophie Zoologique (1809)
Nature's plan of campaign in the production of animals is clearly marked out by this primal and predominant cause, which endows animal life with the ability to complicate organization progressively, and to complicate and perfect gradually, not only the total organization, but also each system of organs in particular, as this cause has been able to establish each one. Now, this plan, that is, this progressive complication of organization, has really been effected by this primal cause among the various animals which exist. But a quite separate cause, an accidental and consequently variable one, has here and there cut across the execution of this plan, without however destroying it, as I shall prove. This cause, in fact, has given rise to whatever real discontinuities there may be in the series, and to the terminated simplicity, and finally to the anomalies to be seen in the various organ-systems of the different organizations. Animaux sans Vertebres, Vol. I (1815)
The progression in the complexity of organization suffers, here and there, in the general series of animals, anomalies produced by the influence of tghe circumstances of the environment, and by those of the habits contracted. Philosophie Zoologique (1809)
The general power which holds in its domain all the things we can perceive...is truly a limited power, and in a manner blind; a power which has neither intention, nor end in view, nor choice, a power which, great as it may be, can do nothing but what in face it does;.....She is, in a way, only an intermediary between GOD and the parts of the physical universe, for the execution of the divine will. [secondary cause] Animaux sans Vertebres, Vol. I (1815)
Lamarck: The Four 'Laws' of Evolution
1. Growth and extension: nature tends to increase the size of organisms to an intrinsic, predetermined limit.
2. The production of new organs results from the supervention of a new need, a mechanical imposition of environmental circumstances.
3. Organic Use and Disuse: the development of organs is directly proportional to the extent to which they are used.
4. Acquired Characteristics: every character that is acquired, impressed, or changed during the course of an individual life can be preserved and transmitted to progeny.
Cuvier's Anatomical Rules
1. Correlation of Parts: every organ of the body is functionally related to every other organ - the cooperation of these organs account for the integrity and vigor of the organism - organs are physiologically related and act on each other and in concert to produce an integrated whole, viz., the complete organism.
2.. Subordination of Characters: certain organs or organ systems are more important to the integrity of the organism than others - relative importance of organ systems: nervous, nutritional-digestive, and locomotion.
James Hutton & Uniformitarianism
The purpose of this Dissertation is to form some estimate with regard to the time the globe of this earth has existed, as a world maintaining plants and animals; to reason with regard to the changes which the earth has undergone; and to see how far an end or termination to this system of things may be perceived, from the consideration of that which has already come to pass.
As it is not in human record, but in natural history, that we are to look for the means of ascertaining what has already been, it is here proposed to which have been transacted in time past. It is thus that, from principles of natural philosophy, we may arrive at some knowledge of order and system in the oeconomy of this globe, and may form a rational opinion with regard to the course of nature, or to events which are in time to happen...
If we would measure the progress of the present land, towards its dissolution by attrition, and its submersion in the ocean, we might discover the actual duration of a former earth; an earth which had supported plants and animals, and had supplied the ocean with those materials which the construction of the present earth required; consequently, we should have the measure of a corresponding space of time, viz., that which has been required in the production of the present land. It, on the contrary, no period can be fixed for the duration or destruction of the present earth, from our observations of those natural observations, which, though unmeasurable, admit of no dubiety, we shall be warranted in drawing the following conclusions; 1st, That it had required an indefinite space of time to have produced the land which now appears; 2dly, That an equal space had been employed upon the construction of that former land from whence the materials of the present came; lastly, That there is presently laying at the bottom of the ocean the foundation of future land, which is to appear after an indefinite space of time.
But, as there is not in human observation proper means for measuring the waste of land upon the globe, it is hence inferred, that we cannot estimate the duration of what we see at present, nor calculate the period at which it had begun; so that, with respect to human observation, this world has neither a beginning nor an end..........'
System of the Earth, its Duration, and Stability (1785)
Charles Robert Darwin (1809-1882)
Evidence Drawn from the Voyage of the Beagle (1831-1836)
1. Succession of types: in some areas species have become extinct (fossil evidence) while other similar species are extant
2. Representative species: adjacent areas of a continent are inhabited by different though similar or apparently related types
3. Resemblance between insular inhabitants and those of the nearest continental mainland
4. Differences, and yet relationships, between the inhabitants of the various islands in the Galapagos Archipelago
5. Geological investigations
initiated by Lyell's Principles of Geology
Variation and Inheritance:
1. Sexual selection and reproduction as a means to 'passing on' a favorable variant, i.e., the promotion of adaption.
2. Dual sense of variety: mutant monsters or 'sports' and mutant forms which adapt to the environment.
3. Heritable variations are fortuitous, viz., at random, by chance.
4. Blending inheritance: characteristics of the offspring are an 'average' between the characteristics of the parents.
5. Pangenesis: each cell of
an organism, in effect, reproduces itself - gemmules derived from each
body part, or cell, serves both for regeneration (growth) and for the transmission
of hereditary elements (generation) via the germ cells, i.e., the gemmules
are 'collected from all parts of the system to constitute the sexual elements,
and their development in the next generation forms a new being;' Animals
and Plants under Domestication, Vol. II, Chapter XXVII
Descent of Organisms: Modification & Collateral Development
1. The development of organisms is basically non-teleological, viz., no apparent purpose, design, or direction is implied.
2. An adaptive 'improvement' does not necessitate an increase in the complexity of an organism; organization may decrease.
3. Species cannot be considered
to have reached a state of 'perfection' - the very possibility of improvement,
in the sense of better adaptability, is evolution.
Natural Selection & the Struggle for Existence
1. The potential reproduction rate of organisms is higher than the increase rate of the food supply, the Mathusian population pressure.
2. The number of individuals within a species remains fairly constant.
3. A high mortality rate is evident: the old die and many of the young do not reach maturity.
4. Individuals within a species are not identical but show variation.
5. Some variants will succeed better that others in the competition to survive within a given environment - the parents of successive generations will be 'naturally selected' from this group as those best able to adapt to this environment.
6. Hereditary resemblance between parent and offspring is an observable fact.
7. The offspring of each generation
will include some individuals which will maintain and improve the adaption
of the parents. Eventually, the new forms will be infertiltle with
the original type and a new species results.
Geo-Physical Evidences for Evolution
1. the combined geological time-scale and the fossil record contained in it.
2. ecological considerations favoring variant forms and their continued adaption to these niches.
3. the geographical distribution
of animals on the earth indicating species evolution in a given area and
Darwin and Organic Evolution
'Darwin's theory of organic evolution, the gradual transformation of species, is based on two independent sets of variables ... the constant occurance of continual competition on both inter- and intra-species levels. In sum, evolution is a natural event(s) which occurs as a consequence of two independent sets of 'causes,' viz., it occurs by chance. Darwin, by force of scientific circumstance, treats variation as a given natural 'fact' while employing natural selection to assimilate the evidence of species (geographical distribution, structural similarity and change) and the fossil record (time). This evidence, in turn, supports the descriptive explanation provided by natural selection; the 'mechanism' of natural selection, if not demonstrated, is rendered cogent and plausible:
'Darwin's chief contribution, not only to Biology but to the whole of natural science, was to have brought to light a process by which contingencies a priori improbable, are given, in the process of time, an increasing probability, until it is their non-occurrence rather than their occurrence which becomes highly improbable.'
R.A. Fisher, The Genetical Theory of Natural Selection, Second Revised Edition (1929)