Introduction to the Reading
Newton's elaboration of the laws of motion and gravitation had a tremendous influence on European thought in all its dimensions. Enlightenment thinkers in the 18th century shared a confident enthusiasm for discovering the laws of nature, especially human nature. This dream was elusive, however. There were many theories, but little real science.
Among those who worked to find a scientific theory of humanity were Karl Marx and Charles Darwin. In 1859, Darwin published The Origin of Species, based upon 20 years of botanical research, and followed it up in 1871 with a second book, The Descent of Man. In these works, Darwin proposed a relatively simple explanation for the natural origins and development of living things, including humanity. The principle of natural selection provided for the first time a physical explanation for human existence, an explanation based, like Newton's theories, upon direct observations of physical nature.
Material nature and human nature were finally linked. A science of humanity was now a reality as it had never been before. As in the case of Newton in the original Scientific Revolution, this new scientific revolution forever altered thinking in every aspect of Western culture. There was a rush to draw out the implications of this theory for philosophy, religion, ethics, politics, law and the arts--and this effort is still going on.
It has often been asserted that Darwin himself never attempted to engage in speculation about the social, ethical or political ramifications of his evolutionary theory, and that he just stuck to the science. This is not true. Your reading is the conclusion to Descent of Man, where Darwin does indeed attempt to draw out the wider implications of his theory. Note that he is quite uncertain in some ways. You may note that he contradicts himself in other ways. I have highlighted some key passages for your special attention. The question for you today is not whether you agree or disagree with Darwin's theory, but what it is, and what consequences this theory has for modern civilization.
What is certain is that the vexing questions raised by Darwin's theory first vexed Darwin himself. If we can understand how Darwin approached the problems of his own theory, and the difficulties he had doing so, we can learn a lot more about the importance of the new science of evolution and its significance for contemporary civilization.
In this piece, Darwin is especially concerned to answer what is perhaps
the most difficult question. Can the unique intellectual and moral
character of human beings be explained by evolution? The answer for
him is yes. But how?
General Summary and Conclusion
 A brief summary will be sufficient to recall to the reader's mind the more salient points in this work. Many of the views which have been advanced are highly speculative, and some no doubt will prove erroneous; but I have in every case given the reasons which have led me to one view rather than to another. It seemed worth while to try how far the principle of evolution would throw light on some of the more complex problems in the natural history of man. False facts are highly injurious to the progress of science, for they often endure long; but false views, if supported by some evidence, do little harm, for every one takes a salutary pleasure in proving their falseness: and when this is done, one path towards error is closed and the road to truth is often at the same time opened.
 The main conclusion here arrived at, and now held by many naturalists
who are well competent to form a sound judgment, is that man is descended
from some less highly organised form. The grounds upon which
this conclusion rests will never be shaken, for the close similarity between
man and the lower animals in embryonic development, as well as in innumerable
points of structure and constitution, both of high and of the most trifling
importance . . .are facts which cannot be disputed. They have long
been known, but until recently they told us nothing with respect to the
origin of man. Now when viewed by the light of our knowledge of the
whole organic world, their meaning is unmistakable. The great principle
of evolution stands up clear and firm, when these groups or facts are considered
in connection with others, such as the mutual affinities of the members
of the same group, their geographical distribution in past and present
times, and their geological succession. It is incredible that all
these facts should speak falsely. He who is not content to look,
like a savage, at the phenomena of nature as disconnected, cannot any longer
believe that man is the work of a separate act of creation. He will
be forced to admit that the close resemblance of the embryo of man to that,
for instance, of a dog--the construction of his skull, limbs and whole
frame on the same plan with that of other mammals, independently of the
uses to which the parts may by put--the occasional re-appearance of various
structures, for instance of several muscles, which man does not normally
possess, but which are common to the Quadrumana--and a crowd of analogous
facts--all point in the plainest manner to the conclusion that man is the
co-descendant with other mammals of a common progenitor.
 The high standard of our intellectual powers and moral disposition is the greatest difficulty which presents itself, after we have been driven to this conclusion on the origin of man. But every one who admits the principle of evolution, must see that the mental powers of the higher animals, which are the same in kind with those of man, though so different in degree, are capable of advancement. Thus the interval between the mental powers of one of the higher apes and of a fish, or between those of an ant and scale-insect, is immense; yet their development does not offer any special difficulty; for with our domesticated animals, the mental faculties are certainly variable, and the variations are inherited. No one doubts that they are of the utmost importance to animals in a state of nature. Therefore the conditions are favourable for their development through natural selection. The same conclusion may be extended to man; the intellect must have been all-important to him, even at a very remote period, as enabling him to invent and use language, to make weapons, tools, traps, etc., whereby with the aid of his social habits, he long ago became the most dominant of all living creatures.
 A great stride in the development of the intellect will have followed, as soon as the half-art and half-instinct of language came into use; for the continued use of language will have reacted on the brain and produced an inherited effect; and this again will have reacted on the improvement of language. As Mr. Chancey Wright has well remarked, the largeness of the brain in man relatively to his body, compared with the lower animals, may be attributed in chief part to the early use of some simple form of language,--that wonderful engine which affixes signs to all sorts of objects and qualities, and excites trains of thought which would never arise from the mere impression of the senses, or if they did arise could not be followed out. The higher intellectual powers of man, such as those of ratiocination, abstraction, self-consciousness, etc., probably follow from the continued improvement and exercise of the other mental faculties.
 The development of the moral qualities is a more interesting problem. The foundation lies in the social instincts, including under this term the family ties. These instincts are highly complex, and in the case of the lower animals give special tendencies towards certain definite actions; but the more important elements are love, and the distinct emotion of sympathy. Animals endowed with the social instincts take pleasure in one another's company, warn one another of danger, defend and aid one another in many ways. These instincts do not extend to all the individuals of the species, but only to those of the same community. As they are highly beneficial to the species, they have in all probability been acquired through natural selection.
 The moral nature of man has reached its present standard, partly through the advancement of his reasoning powers and consequently of just public opinion, but especially from his sympathies having been rendered more tender and widely diffused through the effects of habit, example, instruction, and reflection. It is not improbable that after long practice virtuous tendencies may be inherited. With the more civilised races, the conviction of the existence of an all-seeing Deity has had a potent influence on the advance of morality. Ultimately man does not accept the praise or blame of his fellows as his sole guide, . . .but his habitual convictions, controlled by reason, afford him the safest rule. His consicence then becomes the supreme judge and monitor. Nevertheless the first foundation or origin of the moral sense lies in the social instincts, including sympathy; and these instincts no doubt were primarily gained, as in the case of the lower animals, through natural selection.
 The belief in God has often been advanced as not only the greatest, but the most complete of all the distinctions between man and the lower animals. It is however impossible, as we have seen, to maintain that this belief is innate or instinctive in man. On the other hand a belief in all-pervading spiritual agencies seems to be universal; and apparently follows from a considerable advance in man's reason, and from al still greater advance in his faculties of imagination, curiosity and wonder. I am aware that the assumed instinctive belief in God has been used by many persons as an argument for His existence. But this is a rash argument , as we should thus be compelled to believe in the existence of many cruel and malignant spirits, only a little more powerful than man; for the belief in them is far more general than in a beneficent Deity. The idea of a universal and beneficent Creator does not seem to arise in the mind of man, until he has been elevated by long-continued culture.
. . . .
 I am aware that the conclusions arrived at in this work will be denounced by some as highly irreligious; but he who denounces them is bound to show why it is more irreligious to explain the origin of man as a distinct species by descent from some lower form, through the laws of variation and natural selection, than to explain the birth of the individual through the laws of ordinary reproduction.
 Man scans with scrupulous care the character and pedigree of his horses, cattle, and dogs before he matches them; but when he comes to his own marriage he rarely, or never, takes any such care. He is impelled by nearly the same motives as the lower animals, when they are left to their own free choice, though he is in so far superior to them that he highly values mental charms and virtues. On the other hand he is strongly attracted by mere wealth or rank. Yet he might by selection do something not only for the bodily constitution and frame of his offspring, but for their intellectual and moral qualities. Both sexes ought to refrain from marriage if they are in any marked degree inferior in body or mind; but such hopes are Utopian and will never be even partially realised until the laws of inheritance are thoroughly known. Every one does good service, who aids towards this end. When the principles of breeding and inheritance are better understood, we shall not hear ignorant members of our legislature rejecting with scorn a plan for ascertaining whether or not consanguineous marriages [between closely related people such as cousins] are injurious to man.
 The advancement of the welfare of mankind is a most intricate
problem; all ought to refrain from marriage who cannot avoid abject
poverty for their children; for poverty is not only a great evil, but tends
to its own increase by leading to recklessness in marriage. On the
other hand, as Mr. Galton has remarked, if the prudent avoid marriage,
whilst the reckless marry , the inferior members tend to supplant the better
members of society. Man, like every other animal, has no doubt advanced
to his present high condition through a struggle for existence consequent
on his rapid multiplication; and if he is to advance still higher, it is
to be feared the he must remain subject to a severe struggle. Otherwise
he would sink into indolence, and the more gifted men would not be more
successful in the battle of life than the less gifted. Hence our
natural rate of increase, though leading to many and obvious evils, must
not be greatly diminished by any means. There should be open
competition for all men; and the most able should not be prevented by laws
or customs from succeeding best and rearing the largest number of offspring.
Important as the struggle for existence has been and even still is, yet
as far as the highest part of man's nature is concerned there are other
agencies more important. For the moral qualities are advanced, either
directly or indirectly, much more through the effects of habit, the reasoning
powers, instruction, religion, etc. than through natural selection; though
to this latter agency may be safely attributed the social instincts, which
afforded the basis for the development of the moral sense.