Monday, March 27, 2017

Reading #37: Darwin: The Origin of Species

The Origin of Species
Species, Uniformity, Naturalism, Secondary Causes, God the Creator

I have called this principle, by which each slight variation, if useful, is preserved, by the term Natural Selection, in order to mark its relation to  man's power of selection. But the expression often used by Mr. Herbert Spencer of the Survival of the Fittest is more accurate, and is sometimes equally convenient. We have seen that man by selection can certainly produce great results, and can adapt organic beings to his own uses, through the accumulation of slight but useful variations, given to him by the hand of Nature. But Natural Selection, as we shall hereafter see, is a power incessantly ready for action, and is as immeasurably superior to man's feeble efforts, as the works of Nature are to those of Art.

Nothing is easier than to admit in words the truth of the universal struggle for life, or more difficult — at least, I have found it so — than constantly to bear this conclusion in mind. Yet unless it be thoroughly engrained in the mind, the whole economy of nature, with every fact on distribution, rarity, abundance, extinction, and variation, will be dimly seen or quite misunderstood. We behold the face of nature bright with gladness, we often see superabundance of food; we do not see, or we forget, that the birds which are idly singing round us mostly live on insects or seeds, and are thus constantly destroying life; or we forget how largely these songsters, or their eggs, or their nestlings, are destroyed by birds and beasts of prey; we do not always bear in mind, that, though food may be now superabundant, it is not so at all  seasons of each recurring year. 

A struggle for existence inevitably follows from the high rate at which all organic beings tend to increase. Every being, which during its natural lifetime produces several eggs or seeds, must suffer destruction during some period of its life, and during some season or occasional year, otherwise, on the principle of geometrical increase, its numbers  would quickly become so inordinately great that no country  could support the product. Hence, as more individuals are produced than can possibly survive, there must in every case be a struggle for existence, either one individual with another of the same species, or with the individuals of distinct species, or with the physical conditions of life. It is the doctrine of Malthus applied with manifold force to the whole animal and vegetable kingdoms; for in this case there can be no artificial increase of food, and no prudential restraint from marriage. Although some species may be now increasing, more or less rapidly, in numbers, all cannot do so, for the world would not hold them.   There is no exception to the rule that every organic being naturally increases at so high a rate, that, if not destroyed, the earth would soon be covered by the progeny of a single pair.

It has been said that I speak of natural selection as an active power or Deity; but who objects to an author speaking of the attraction of gravity as ruling the movements of the planets? Every one knows what is meant and is implied by such metaphorical expressions; and they are almost necessary for brevity. So again it is difficult to avoid personifying the word Nature; but I mean by Nature, only the aggregate action and product of many natural laws, and by laws the sequence of events as ascertained by us.

It may metaphorically be said that natural selection is daily and hourly scrutinizing, throughout the world, the slightest variations; rejecting those that are bad, preserving and adding up all that are good; silently and insensibly working, whenever and wherever opportunity offers, at the improvement of each organic being in relation to its organic and inorganic conditions of life. We see nothing of these slow changes in progress, until the hand of time has marked the lapse of ages, and then so imperfect is our view into long past geological ages, that we see only that the forms of life  are now different from what they formerly were.


It may be asked how far I extend the doctrine of the modification of species. The question is difficult to answer because the more distinct the forms are which we consider, by  so much the arguments in favour of community of descent  become fewer in number and less in force. But some  arguments of the greatest weight extend very far. All  the members of whole classes are connected together by  a chain of affinities, and all can be classed on the same  principle, in groups subordinate to groups. Fossil remains  sometimes tend to fill up very wide intervals between existing orders.


When the views advanced by me in this volume, and by  Mr. Wallace, or when analogous views on the origin of species are generally admitted, we can dimly foresee that there  will be a considerable revolution in natural history. Systematists will be able to pursue their labours as at present;  but they will not be incessantly haunted by the shadowy  doubt whether this or that form be a true species. This, I  feel sure and I speak after experience, will be no slight re-  lief. The endless disputes whether or not some fifty species  of British brambles are good species will cease. Systematists  will have only to decide (not that this will be easy) whether  any form be sufficiently constant and distinct from other  forms, to be capable of definition; and if definable, whether  the differences be sufficiently important to deserve a specific  name. This latter point will become a far more essential consideration than it is at present; for differences, however  slight, between any two forms, if not blended by intermediate gradations, are looked at by most naturalists as sufficient to raise both forms to the rank of species.   

Hereafter we shall be compelled to acknowledge that the  only distinction between species and well-marked varieties is,  that the latter are known, or believed, to be connected at the  present day by intermediate gradations whereas species were  formerly thus connected. Hence, without rejecting the consideration of the present existence of intermediate gradations between any two forms, we shall be led to weigh more  carefully and to value higher the actual amount of difference  between them. It is quite possible that forms now generally  acknowledged to be merely varieties may hereafter be  thought worthy of specific names; and in this case scientific  and common language will come into accordance. In short,  we shall have to treat species in the same manner as those  naturalists treat genera, who admit that genera are merely  artificial combinations made for convenience. This may not  be a cheering prospect; but we shall at least be freed from  the vain search for the undiscovered and undiscoverable  essence of the term species.   

The other and more general departments of natural history  will rise greatly in interest. The terms used by naturalists,  of affinity, relationship, community of type, paternity, morphology, adaptive characters, rudimentary and aborted  organs, &c., will cease to be metaphorical, and will have a  plain signification. When we no longer look at an organic  being as a savage looks at a ship, as something wholly beyond his comprehension ; when we regard every production  of nature as one which has had a long history; when we  contemplate every complex structure and instinct as the  summing up of many contrivances, each useful to the possessor, in the same way as any great mechanical invention  is the summing up of the labour, the experience, the reason,  and even the blunders of numerous workmen ; when we  thus view each organic being, how far more interesting — I  speak from experience — does the study of natural history  become 

A grand and almost untrodden field of inquiry will be opened, on the causes and laws of variation, on correlation,  on the effects of use and disuse, on the direct action of external conditions, and so forth. The study of domestic productions will rise immensely in value. A new variety raised  by man will be a more important and interesting subject for  study than one more species added to the infinitude of already  recorded species. Our classifications will come to be, as far  as they can be so made, genealogies ; and will then truly give  what may be called the plan of creation. The rules for  classifying will no doubt become simpler when we have a  definite object in view. We possess no pedigrees or armorial  bearings; and we have to discover and trace the many diverging lines of descent in our natural genealogies, by characters of any kind which have long been inherited. Rudimentary organs will speak infallibly with respect to the  nature of long-lost structures. Species and groups of species  which are called aberrant, and which may fancifully be  called having fossils, will aid us in forming a picture of the  ancient forms of life. Embryology will often reveal to us  the structure, in some degree obscured, of the prototypes of  each great class.   

When we can feel assured that all the individuals of the  same species, and all the closely allied species of most genera,  have within a not very remote period descended from one  parent, and have migrated from some one birth-place; and  when we better know the many means of migration, then, by  the light which geology now throws, and will continue to  throw, on former changes of climate and of the level of the  land, we shall surely be enabled to trace in an admirable  manner the former migrations of the inhabitants of the whole  world. Even at present, by comparing the differences be-  tween the inhabitants of the sea on the opposite sides of a  continent, and the nature of the various inhabitants on that  continent in relation to their apparent means of immigration,  some light can be thrown on ancient geography.   

The noble science of Geology loses glory from the extreme  imperfection of the record. The crust of the earth with its  imbedded remains must not be looked at as a well-filled  museum, but as a poor collection made at hazard and at rare  intervals. The accumulation of each great fossiliferous formation will be recognised as having depended on an unusual concurrence of favourable circumstances, and the blank intervals between the successive stages as having been of vast  duration. But we shall be able to gauge with some security  the duration of these intervals by a comparison of the preceding and succeeding organic forms. We must be cautious  in attempting to correlate as strictly contemporaneous two  formations, which do not include many identical species, by  the general succession of the forms of life. As species are  produced and exterminated by slowly acting and still exist-  ing causes, and not by miraculous acts of creation; and as  the most important of all causes of organic change is one  which is almost independent of altered and perhaps suddenly altered physical conditions, namely, the mutual relation of organism to organism, — the improvement of one  organism entailing the improvement or the extermination  of others ; it follows, that the amount of organic change in  the fossils of consecutive formations probably serves as a  fair measure of the relative, though not actual lapse of  time. A number of species, however, keeping in a body  might remain for a long period unchanged, whilst within  the same period, several of these' species by migrating into  new countries and coming into competition with foreign  associates, might become modified; so that we must not  overrate the accuracy of organic change as a measure of  time.   

In the future I see open fields for far more important researches. Psychology will be securely based on the foundation already well laid by Mr. Herbert Spencer, that of the  necessary acquirement of each mental power and capacity by  gradation. Much light will be thrown on the origin of man  and his history.   

Authors of the highest eminence seem to be fully satisfied  with the view that each species has been independently created. To my mind it accords better with what we know of  the laws impressed on matter by the Creator, that the production and extinction of the past and present inhabitants  of the world should have been due to secondary causes, like  those determining the birth and death of the individual.  When I view all beings not as special creations, but as the lineal descendants of some few beings which lived long before the first bed of the Cambrian system was deposited,  they seem to me to become ennobled. Judging from the past,  we may safely infer that not one living species will transmit  its unaltered likeness to a distant futurity. And of the  species now living very few will transmit progeny of any  kind to a far distant futurity; for the manner in which all  organic beings are grouped, shows that the greater number  of species in each genus, and all the species in many genera,  have left no descendants, but have become utterly extinct.  We can so far take a prophetic glance into futurity as to  foretell that it will be the common and widely-spread species,  belonging to the larger and dominant groups within each  class, which will ultimately prevail and procreate new and  dominant species. As all the living forms of life are the  lineal descendants of those which lived long before the Cambrian epoch, we may feel certain that the ordinary succession by generation has never once been broken, and that no  cataclysm has desolated the whole world. Hence we may  look with some confidence to a secure future of great length.  And as natural selection works solely by and for the good  of each being, all corporeal and mental endowments will tend  to progress towards perfection.

Study Questions:
1.     Has there always been struggle and suffering?  How can we know?
2.     Does natural selection require natural evil?
3.     Can variation occur without natural evil?
4.     When does variation lead to a new species as opposed to continued variation within a species?
5.     What does it mean for the Creator to impose laws on nature?
6.     What are secondary causes?  What is the primary cause?
7.     Has the Creator acted to change creation after the beginning?
8.     Why is there natural evil and struggle for life?
9.     What did Malthus say about the growth of populations?  Must this be true?
10. What is uniformity (uniformitarianism) and how does it apply to explaining origins? (Charles Lyell)
11. What methods are used to explain the age of the earth?
12. Do these dating methods have philosophical presuppositions?