The Descent of Man on Superphysics

The Evidence Of The Descent Of Man From Some Lower Form

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First Edition February 24, 1871. Second Edition September, 1874.

Birds

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When the sexes differ in beauty or in the power of singing, or in producing what I have called instrumental music, it is almost invariably the male who surpasses the female. These qualities, as we have just seen, are evidently of high importance to the male. When they are gained for only a part of the year it is always before the breeding-season. It is the male alone who elaborately displays his varied attractions, and often performs strange antics on the ground or in the air, in the presence of the female. Each male drives away, or if he can, kills his rivals. Hence we may conclude that it is the object of the male to induce the female to pair with him, and for this purpose he tries to excite or charm her in various ways; and this is the opinion of all those who have carefully studied the habits of living birds. But there remains a question which has an all important bearing on sexual selection, namely, does every male of the same species excite and attract the female equally? Or does she exert a choice, and prefer certain males? This latter question can be answered in the affirmative by much direct and indirect evidence. It is far more difficult to decide what qualities determine the choice of the females; but here again we have some direct and indirect evidence that it is to a large extent the external attractions of the male; though no doubt his vigour, courage, and other mental qualities come into play. We will begin with the indirect evidence.

Birds

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I have explained why:

the females of many birds have not acquired the same ornaments as the male
both sexes of many other birds are almost equally ornamented

In my ‘Origin of Species’, I briefly suggested that the long tail of the peacock would be inconvenient and the conspicuous black colour of the male capercailzie dangerous, to the female during the period of incubation: and consequently that the transmission of these characters from the male to the female offspring had been checked through natural selection.

Birds

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Transmission of characters, as limited by age, in sexual selection

With animals of all kinds when the adults differ in colour from the young, and the colours of the latter are not, as far as we can see, of any special service, they may generally be attributed, like various embryological structures, to the retention of a former character.

Birds

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Class 2: When The Adult Female Is More Conspicuous Than The Adult Male, The Young Of Both Sexes In Their First Plumage Resemble The Adult Male.

This class is exactly the reverse of the last.

Man as a Social Animal

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Man as a social being is seen in his dislike of solitude, and in his wish for society beyond that of his own family.

Solitary confinement is one of the severest punishments which can be inflicted. Some authors suppose that man primevally lived in single families; but at the present day, though single families, or only two or three together, roam the solitudes of some savage lands, they always, as far as I can discover, hold friendly relations with other families inhabiting the same district. Such families occasionally meet in council, and unite for their common defence. It is no argument against savage man being a social animal, that the tribes inhabiting adjacent districts are almost always at war with each other; for the social instincts never extend to all the individuals of the same species.

Mental Qualities Of Birds, And Their Taste For The Beautiful

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The mental powers of birds

The mental powers of birds is ranked low.

PRINCIPLES OF SEXUAL SELECTION

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With animals which have their sexes separated, the males necessarily differ from the females in their organs of reproduction.

These are the primary sexual characters.

Secondary Sexual Characters In The Lower Classes Of The Animal Kingdom

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With animals belonging to the lower classes, the two sexes are not rarely united in the same individual, and therefore secondary sexual characters cannot be developed. In many cases where the sexes are separate, both are permanently attached to some support, and the one cannot search or struggle for the other. Moreover it is almost certain that these animals have too imperfect senses and much too low mental powers to appreciate each other’s beauty or other attractions, or to feel rivalry.

Secondary Sexual Characters Of Birds

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Secondary sexual characters are more diversified and conspicuous in birds, though not perhaps entailing more important changes of structure, than in any other class of animals. I shall, therefore, treat the subject at considerable length. Male birds sometimes, though rarely, possess special weapons for fighting with each other.

Secondary Sexual Characters Of Insects

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In many insects, the sexes sometimes differ in their locomotive-organs, and often in their sense-organs.

An example is the antennae of the males of many species.

In Chloeon, one of the Ephemerae, the male has great pillared eyes, of which the female is entirely destitute.

Sociability

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Many animals are social.

The most common mutual service in the higher animals is to warn one another of danger through the united senses of all.

The Moral Faculties

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I agree that of all the differences between man and the lower animals, the moral sense or conscience is by far the most important.

Mackintosh says that this “has a rightful supremacy over every other principle of human action”

THE RACES OF MAN

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I do not intend here to describe the races of men.

I will explain:

the value of the differences between
and how they have originated

In determining whether two or more allied forms ought to be ranked as species or varieties, naturalists are practically guided by the following considerations; namely, the amount of difference between them, and whether such differences relate to few or many points of structure, and whether they are of physiological importance; but more especially whether they are constant. Constancy of character is what is chiefly valued and sought for by naturalists.

Rudiments

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All of the higher animals have a rudimentary condition.

Rudimentary organs are opposed to the nascent organs.

Rudimentary ones are either absolutely useless, such as the mammae of male quadrupeds, or the incisor teeth of ruminants which never cut through the gums; or they are of such slight service to their present possessors, that we can hardly suppose that they were developed under the conditions which now exist. Organs in this latter state are not strictly rudimentary, but they are tending in this direction.
Nascent organs are not fully developed. But they are of high service to their possessors, and are capable of further development.

Rudimentary organs are eminently variable; and this is partly intelligible, as they are useless, or nearly useless, and consequently are no longer subjected to natural selection. They often become wholly suppressed. When this occurs, they are nevertheless liable to occasional reappearance through reversion—a circumstance well worthy of attention.

AMPHIBIANS

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URODELA

I will begin with the tailed amphibians.

Difference In The Mental Powers Of The Two Sexes

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With respect to differences of this nature between man and woman, it is probable that sexual selection has played a highly important part. I am aware that some writers doubt whether there is any such inherent difference; but this is at least probable from the analogy of the lower animals which present other secondary sexual characters. No one disputes that the bull differs in disposition from the cow, the wild-boar from the sow, the stallion from the mare, and, as is well known to the keepers of menageries, the males of the larger apes from the females.

Display

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The bright colours of many butterflies and of some moths are for display, so that they may be readily seen.

During the night, colours are not visible.

This is why nocturnal moths are much less gaily decorated than butterflies, all of which are diurnal in their habits.

Equal Transmission Of Ornamental Characters To Both Sexes

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With many birds, ornaments, which analogy leads us to believe were primarily acquired by the males, have been transmitted almost equally to both sexes.

How far does this apply to mammals?

GENERAL A SUMMARY AND CONCLUSION

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Main conclusion that man is descended from some lower form—Manner of development—Genealogy of man—Intellectual and moral faculties—Sexual Selection—Concluding remarks.

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.

Insects Order Lepidoptera. (Butterflies And Moths.)

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In this great Order the most interesting points for us are the differences in colour between the sexes of the same species, and between the distinct species of the same genus. Nearly the whole of the following chapter will be devoted to this subject; but I will first make a few remarks on one or two other points.

Secondary Sexual Characters Of Fishes, Amphibians, And Reptiles

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The lowest class of vertebrae are of fishes.

The males of Plagiostomous fishes (sharks, rays) and of Chimaeroid fishes have claspers to retain the female, like the various structures possessed by many of the lower animals.

Secondary Sexual Characters Of Mammals

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With mammals the male appears to win the female much more through the law of battle than through the display of his charms. The most timid animals, not provided with any special weapons for fighting, engage in desperate conflicts during the season of love. Two male hares have been seen to fight together until one was killed; male moles often fight, and sometimes with fatal results; male squirrels engage in frequent contests, “and often wound each other severely”; as do male beavers, so that “hardly a skin is without scars.” (1. See Waterton’s account of two hares fighting, ‘Zoologist,’ vol. i. 1843, p. 211. On moles, Bell, ‘Hist. of British Quadrupeds,’ 1st ed., p. 100. On squirrels, Audubon and Bachman, Viviparous Quadrupeds of N. America, 1846, p. 269. On beavers, Mr. A.H. Green, in ‘Journal of Linnean Society, Zoology,’ vol. x. 1869, p. 362.) I observed the same fact with the hides of the guanacoes in Patagonia; and on one occasion several were so absorbed in fighting that they fearlessly rushed close by me. Livingstone speaks of the males of the many animals in Southern Africa as almost invariably shewing the scars received in former contests.

Secondary Sexual Characters Of Mammals

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Quadrupeds use their voices to:

signal danger
call from one member of a troop to another
call for lost offspring
call for protection to their mother

But I am concerned only with the difference between the voices of the sexes, between:

Secondary Sexual Characters Of Man

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Differences between man and woman—Causes of such differences and of certain characters common to both sexes—Law of battle—Differences in mental powers, and voice—On the influence of beauty in determining the marriages of mankind—Attention paid by savages to ornaments—Their ideas of beauty in woman—The tendency to exaggerate each natural peculiarity.

SECONDARY SEXUAL CHARACTERS OF MAN

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On the effects of the continued selection of women according to a different standard of beauty in each race—On the causes which interfere with sexual selection in civilised and savage nations—Conditions favourable to sexual selection during primeval times—On the manner of action of sexual selection with mankind—On the women in savage tribes having some power to choose their husbands—Absence of hair on the body, and development of the beard—Colour of the skin—Summary.

The Affinities And Genealogy Of Man

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Position of man in the animal series—The natural system genealogical—Adaptive characters of slight value—Various small points of resemblance between man and the Quadrumana—Rank of man in the natural system—Birthplace and antiquity of man—Absence of fossil connecting links—Lower stages in the genealogy of man, as inferred, firstly from his affinities and secondly from his structure—Early androgynous condition of the Vertebrata—Conclusion.

The Development Of Man From Some Lower Form

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Man is now subject to much variability.

No two individuals of the same race are alike.

There is a lot of diversity in the proportions and dimensions of the various parts of the body.

The Development Of The Intellectual And Moral Faculties During Primeval And Civilised Times

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Advancement of the intellectual powers through natural selection—Importance of imitation—Social and moral faculties—Their development within the limits of the same tribe—Natural selection as affecting civilised nations—Evidence that civilised nations were once barbarous.

Reversion

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Many of the cases to be here given, might have been introduced under the last heading.

Reversion is when a structure is arrested in its development but still continues growing.

Abstraction, General Conceptions, Self-Consciousness, Mental Individuality

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It would be very difficult for any one with even much more knowledge than I possess, to determine how far animals exhibit any traces of these high mental powers.

This difficulty arises from the impossibility of judging what passes through the mind of an animal; and again, the fact that writers differ to a great extent in the meaning which they attribute to the above terms, causes a further difficulty. If one may judge from various articles which have been published lately, the greatest stress seems to be laid on the supposed entire absence in animals of the power of abstraction, or of forming general concepts.

Comparison Of The Mental Powers Of Man And The Lower Animals

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The difference in mental power between the highest ape and the lowest savage, immense—Certain instincts in common—The emotions—Curiosity—Imitation—Attention—Memory— Imagination—Reason—Progressive improvement —Tools and weapons used by animals—Abstraction, Self-consciousness—Language—Sense of beauty—Belief in God, spiritual agencies, superstitions.

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REPTILES.

CHELONIA.

Tortoises and turtles do not have well-marked sexual differences.

In some species, the tail of the male is longer than that of the female.

In some, the plastron or lower surface of the shell of the male is slightly concave in relation to the back of the female.

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CLASS VI. — THE YOUNG IN THEIR FIRST PLUMAGE DIFFER FROM EACH OTHER ACCORDING TO SEX; THE YOUNG MALES RESEMBLING MORE OR LESS CLOSELY THE ADULT MALES, AND THE YOUNG FEMALES MORE OR LESS CLOSELY THE ADULT FEMALES.