or the Preservation of Favoured Races in the Struggle for Life.
Contents, evidence, conclusion, meaning
An African elephant in her home range, Krueger National Park, S.A., [J. Siry. 2002] and a yearling in the Etosha Pan of the Namibian desert. [J. Siry. 2013].
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Table of Contents | |
| Chapters | ||
| 1 | Variation under Domestication | |
| 2 | Variation under Nature |  |
| 3 | Struggle for Existence | |
| 4 | Natural Selection | |
| 5 | Laws of Variation | |
| 6 | Difficulties on Theory | |
| 7 | Instinct | |
| 8 | Hybridization | |
| 9 | On the Imperfection of the Geological Record | |
| 10 | On the Geological succession of organic beings | |
| 11 | Geographical Distribution (A) | |
| 12 | Geographical Distribution (B) | |
| 13 | Mutual Affinities of Organic Beings | |
| 14 | Recapitulation and Conclusion | |
| Charles Darwin in 1855 just before receiving Wallace's letter and manuscript. | ||
"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 history; when we contemplate every complex structure as and instinct as the summing up of many contrivances, each useful to the possessor, nearly in the same way as when we look at any great mechanical invention as the summing of labor, the experience, the reason and even the blunders of numerous workmen; when we thus view each organic being, how far more interesting,...will the study of natural history become."
(pp. 485-86.)
When on board H.M.S. 'Beagle,' as a naturalist, I was much struck with certain facts in the distribution of the inhabitants of South America, and in the geological relations of the present to the past inhabitants of that continent. These facts seem to me to throw some light on the origin of species -- that mystery of mysteries, as it has been called by one of our greatest philosophers."
(1)
1 Variation under Domestication
"When we look to the individuals of the same variety or sub-variety of our older cultivated plants and animals, one of the first points which strikes us, is, that they generally differ much more from each other than do the individuals of any one species or variety in the state of nature."
"It seems pretty clear that organic beings must be exposed during several generations to the new conditions of life to cause any appreciable amount of variation; and that when the organism has once begun to vary, it generally continues to vary for many generations."
page 7.
2 Variation under Nature
"I look at the term species, as one arbitrarily given for the sake of convenience to a set of individuals closely resembling each other, and that it does not essentially differ from the term variety, which is given to less distinct and more fluctuating forms."
(52)
"Finally, then, varieties have the same general characteristics of species, for they can not be distinguished from species,-- except, firstly, by the discovery of intermediate linking forms, and the occurrence of such links cannot affect the actual characters of the forms which they connect;...but the amount of difference considered necessary to give to two forms the rank of species is quite indefinite."
(58-59)
"we can clearly understand these analogies [varieties to species], if species have once existed as varieties, and have thus originated: whereas, these analogies are utterly inexplicable if each species has been independently created."
(59)
"And thus, the forms of life throughout the universe become divided into groups subordinate to groups."
3 Struggle for Existence
"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 natural selection, as we shall see, is a power incessantly ready for action, and is immeasurably superior to man"s feeble efforts,..." (61)
"all organic beings are exposed to severe competition." (62)
"I use the term Struggle for Existence in the large and metaphorical sense, including the dependence of one being on another, and including not only the life of the individual, but success in leaving progeny." (62)
"A struggle for existence inevitably follows from the high rate at which all organic beings tend to increase." (63)
"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." (64)
I am tempted to give one more instance showing how plants and animals, most remote in the scale of nature, are bound together by a web of complex relations. I shall hereafter have occasion to show that the exotic Lobelia fulgens, in this part of England, is never visited by insects, and consequently, from its peculiar structure, never can set a seed. Many of our orchidaceous plants absolutely require the visits of moths to remove their pollen-masses and thus to fertilise them. I have, also, reason to believe that humble-bees are indispensable to the fertilisation of the heartsease (Viola tricolor), for other bees do not visit this flower. From experiments which I have tried, I have found that the visits of bees, if not indispensable, are at least highly beneficial to the fertilisation of our clovers; but humble-bees alone visit the common red clover (Trifolium pratense), as other bees cannot reach the nectar. Hence I have very little doubt, that if the whole genus of humble-bees became
[page] 74, MUTUAL CHECKS TO INCREASE. CHAP. III.
extinct or very rare in England, the heartsease and red clover would become very rare, or wholly disappear. The number of humble-bees in any district depends in a great degree on the number of field-mice, which destroy their combs and nests; and Mr. H. Newman, who has long attended to the habits of humble-bees, believes that "more than two thirds of them are thus destroyed all over England." Now the number of mice is largely dependent, as every one knows, on the number of cats; and Mr. Newman says, "Near villages and small towns I have found the nests of humble-bees more numerous than elsewhere, which I attribute to the number of cats that destroy the mice." Hence it is quite credible that the presence of a feline animal in large numbers in a district might determine, through the intervention first of mice and then of bees, the frequency of certain flowers in that district!
pp. 73-74.
"Even slow-breeding man has doubled in twenty-five years, and at this rate, in a few thousand years, there would literally not be standing room for his progeny."
"It will convince us of our ignorance on the mutual relations of all organic beings; a conviction as necessary, as it seems to be difficult to acquire." (78)
All that we can do, is to keep steadily in mind that each organic being is striving to increase at a geometrical ratio; that each at some period of its life, during some season of the year, during each generation or at intervals, has to struggle for life and to suffer great destruction."
(79)
When we reflect on this struggle, we may console ourselves with the full belief, that war of nature is not incessant, that no fear is felt, that death is generally prompt, and that the vigorous, the healthy, and the happy survive and multiply."
(79)
4 Natural Selection
"Let it be borne in mind how infinitely complex and close fitting are the mutual relations of all organic beings to each other and to the physical conditions of life." (80)
"This preservation of favorable variations and the rejection of injurious variations, I call Natural Selection." (81)
"We shall best understand the probable course of natural selection by taking the case of a country undergoing some physical change, for instance, of climate." (81)
"In such a case, every slight modification, which in the course of the ages chanced to arise, and which in any way favored the individuals of any species, by better adapting them to their altered conditions, would tend to be preserved; an natural selection would thus have free scope for the work of improvement." (82)
"nature cares nothing for appearances, except in so far as they may be useful to any being. She can act on every internal organ, on every shade of constitutional difference, on the whole machinery of life." (83)
"Under nature, the slightest difference of structure or constitution may well turn the nicely-balanced scale in the struggle for life, and so be preserved." (83-84)
"It may be said that natural selection is daily and hourly scrutinizing, throughout the world, every variation, even the slightest,... silently and incessantly working, whenever and wherever opportunity offers, at the improvement of each organic being relation to its organic and inorganic conditions of life." (84)
"This principle of preservation, I have called, for the sake of brevity, Natural Selection. Natural selection, on the principle of qualities being inherited at corresponding ages, can modify the egg, seed, or young, as easily as the adult."
(127)
Natural selection, also, leads to divergence of character; for more living beings can be supported on the same area the more they diverge in structure, habits and constitution, of which see proof by looking at the inhabitants of any small spot or at naturalized productions."
(127-28)
"Therefore..., the more diversified these descendants become, the better will be their chance of succeeding in the battle for life." (128)
"The affinities of all the beings of the same class have sometimes been represented by a giant tree."
(129)
"As buds give rise by growth by growth to fresh buds, and these, if vigorous, branch out and overtop on all sides many a feebler branch, so by generation I believe it has been with the great Tree of Life, which fills with its dead and broken branches the crust of the earth, and covers the surface with its ever branching and beautiful ramifications."
(130)
5 Laws of Variation
"Nevertheless, we can here and there dimly catch a faint ray of light, and we may feel sure that there must be some cause for each deviation of structure, however slight." (132)
How much direct effect difference of climate, food, & c., produces on any being is extremely doubtful."
"complex co-adaptations of structure between one organic being and another, which we see everywhere throughout nature."
(132)
"When a variation is of the slightest use to a being, we cannot tell how much of it to attribute to the accumulative action of natural selection, and how much to the conditions of life."
(133)
the effects of use & disuse (134)
Acclimatization -" Habit is hereditary with plants, as in the period of flowering, in the amount of rain requisite for seeds to germinate, in the time of sleep,..." (139)
"as Goethe expressed it, "in order to spend on one side, nature is forced to economize on the other side." I think this holds true to a certain extent with our domestic productions..."
(147)
"A part developed in any species in an extraordinary degree or manner, in comparison with the same part in allied species, tends to be highly variable."
["with respect to the length of the arms of the ourang-outang"] (150)
"Distinct species present analogous variations; and a variety of one species often assumes some of the characters of an allied species, or reverts to some of the characters of an allied species, or reverts to some of the characters of an early progenitor."
(159)
"Habit in producing constitutional differences, and use in strengthening, and disuse in weakening and diminishing organs, seem to have been more potent in their effects."
(167-68)
"Although new and important modifications may not arise from reversion and analogous variation, such modifications will add to the beautiful and harmonious diversity of nature."
(169)
"Whatever the cause may be of each slight difference in the offspring from their parents -- and a cause for each must exist -- it is the steady accumulation; through natural selection, of such differences, when beneficial to the individual, that gives rise to all the more important modifications of structure, by which the innumerable beings on the face of this earth are enabled to struggle with each other, and the best adapted to survive."
(170)
6 Difficulties on Theory
important manner on the presence of other already defined
organic forms, than on climate; and, therefore, that the really governing
conditions of life do not graduate away quite insensibly like heat or moisture." 
"Notwithstanding this parallelism (of climates and features
in the continents) in
the conditions of the Old and New Worlds, how widely different are their living
productions!"
"Conditions of Existence is the
higher law;"
