A	>>	B	>>	C	>>	D	>>	E
F	>>	G	>>	H	>>	I	>>	J
K	>>	L	>>	M	>>	N	>>	O
P	>>	R	>>	S	>>	T	>>	U
V	>>	W	>>			X	>>	Z

Amy Lowell - "A Dome of Many Coloured Glass"

Henry James - "The Coxon Fund"

Eliza Burt Gamble - "The God Idea of the Ancients or Sex in Religion"

Fyodor Dostoyevsky - "Poor Folk"

The Descent of Man and Selection in Relation to Sex

C >> Charles Darwin >> The Descent of Man and Selection in Relation to Sex




He who wishes to decide whether man is the modified descendant of some pre-
existing form, would probably first enquire whether man varies, however
slightly, in bodily structure and in mental faculties; and if so, whether
the variations are transmitted to his offspring in accordance with the laws
which prevail with the lower animals. Again, are the variations the
result, as far as our ignorance permits us to judge, of the same general
causes, and are they governed by the same general laws, as in the case of
other organisms; for instance, by correlation, the inherited effects of use
and disuse, etc.? Is man subject to similar malconformations, the result
of arrested development, of reduplication of parts, etc., and does he
display in any of his anomalies reversion to some former and ancient type
of structure? It might also naturally be enquired whether man, like so
many other animals, has given rise to varieties and sub-races, differing
but slightly from each other, or to races differing so much that they must
be classed as doubtful species? How are such races distributed over the
world; and how, when crossed, do they react on each other in the first and
succeeding generations? And so with many other points.

The enquirer would next come to the important point, whether man tends to
increase at so rapid a rate, as to lead to occasional severe struggles for
existence; and consequently to beneficial variations, whether in body or
mind, being preserved, and injurious ones eliminated. Do the races or
species of men, whichever term may be applied, encroach on and replace one
another, so that some finally become extinct? We shall see that all these
questions, as indeed is obvious in respect to most of them, must be
answered in the affirmative, in the same manner as with the lower animals.
But the several considerations just referred to may be conveniently
deferred for a time: and we will first see how far the bodily structure of
man shews traces, more or less plain, of his descent from some lower form.
In succeeding chapters the mental powers of man, in comparison with those
of the lower animals, will be considered.

THE BODILY STRUCTURE OF MAN.

It is notorious that man is constructed on the same general type or model
as other mammals. All the bones in his skeleton can be compared with
corresponding bones in a monkey, bat, or seal. So it is with his muscles,
nerves, blood-vessels and internal viscera. The brain, the most important
of all the organs, follows the same law, as shewn by Huxley and other
anatomists. Bischoff (1. 'Grosshirnwindungen des Menschen,' 1868, s. 96.
The conclusions of this author, as well as those of Gratiolet and Aeby,
concerning the brain, will be discussed by Prof. Huxley in the Appendix
alluded to in the Preface to this edition.), who is a hostile witness,
admits that every chief fissure and fold in the brain of man has its
analogy in that of the orang; but he adds that at no period of development
do their brains perfectly agree; nor could perfect agreement be expected,
for otherwise their mental powers would have been the same. Vulpian (2.
'Lec. sur la Phys.' 1866, page 890, as quoted by M. Dally, 'L'Ordre des
Primates et le Transformisme,' 1868, page 29.), remarks: "Les differences
reelles qui existent entre l'encephale de l'homme et celui des singes
superieurs, sont bien minimes. Il ne faut pas se faire d'illusions a cet
egard. L'homme est bien plus pres des singes anthropomorphes par les
caracteres anatomiques de son cerveau que ceux-ci ne le sont non seulement
des autres mammiferes, mais meme de certains quadrumanes, des guenons et
des macaques." But it would be superfluous here to give further details on
the correspondence between man and the higher mammals in the structure of
the brain and all other parts of the body.

It may, however, be worth while to specify a few points, not directly or
obviously connected with structure, by which this correspondence or
relationship is well shewn.

Man is liable to receive from the lower animals, and to communicate to
them, certain diseases, as hydrophobia, variola, the glanders, syphilis,
cholera, herpes, etc. (3. Dr. W. Lauder Lindsay has treated this subject
at some length in the 'Journal of Mental Science,' July 1871; and in the
'Edinburgh Veterinary Review,' July 1858.); and this fact proves the close
similarity (4. A Reviewer has criticised ('British Quarterly Review,' Oct.
1st, 1871, page 472) what I have here said with much severity and contempt;
but as I do not use the term identity, I cannot see that I am greatly in
error. There appears to me a strong analogy between the same infection or
contagion producing the same result, or one closely similar, in two
distinct animals, and the testing of two distinct fluids by the same
chemical reagent.) of their tissues and blood, both in minute structure and
composition, far more plainly than does their comparison under the best
microscope, or by the aid of the best chemical analysis. Monkeys are
liable to many of the same non-contagious diseases as we are; thus Rengger
(5. 'Naturgeschichte der Saugethiere von Paraguay,' 1830, s. 50.), who
carefully observed for a long time the Cebus Azarae in its native land,
found it liable to catarrh, with the usual symptoms, and which, when often
recurrent, led to consumption. These monkeys suffered also from apoplexy,
inflammation of the bowels, and cataract in the eye. The younger ones when
shedding their milk-teeth often died from fever. Medicines produced the
same effect on them as on us. Many kinds of monkeys have a strong taste
for tea, coffee, and spiritous liquors: they will also, as I have myself
seen, smoke tobacco with pleasure. (6. The same tastes are common to some
animals much lower in the scale. Mr. A. Nichols informs me that he kept in
Queensland, in Australia, three individuals of the Phaseolarctus cinereus;
and that, without having been taught in any way, they acquired a strong
taste for rum, and for smoking tobacco.) Brehm asserts that the natives of
north-eastern Africa catch the wild baboons by exposing vessels with strong
beer, by which they are made drunk. He has seen some of these animals,
which he kept in confinement, in this state; and he gives a laughable
account of their behaviour and strange grimaces. On the following morning
they were very cross and dismal; they held their aching heads with both
hands, and wore a most pitiable expression: when beer or wine was offered
them, they turned away with disgust, but relished the juice of lemons. (7.
Brehm, 'Thierleben,' B. i. 1864, s. 75, 86. On the Ateles, s. 105. For
other analogous statements, see s. 25, 107.) An American monkey, an
Ateles, after getting drunk on brandy, would never touch it again, and thus
was wiser than many men. These trifling facts prove how similar the nerves
of taste must be in monkeys and man, and how similarly their whole nervous
system is affected.

Man is infested with internal parasites, sometimes causing fatal effects;
and is plagued by external parasites, all of which belong to the same
genera or families as those infesting other mammals, and in the case of
scabies to the same species. (8. Dr. W. Lauder Lindsay, 'Edinburgh Vet.
Review,' July 1858, page 13.) Man is subject, like other mammals, birds,
and even insects (9. With respect to insects see Dr. Laycock, "On a
General Law of Vital Periodicity," 'British Association,' 1842. Dr.
Macculloch, 'Silliman's North American Journal of Science,' vol. XVII. page
305, has seen a dog suffering from tertian ague. Hereafter I shall return
to this subject.), to that mysterious law, which causes certain normal
processes, such as gestation, as well as the maturation and duration of
various diseases, to follow lunar periods. His wounds are repaired by the
same process of healing; and the stumps left after the amputation of his
limbs, especially during an early embryonic period, occasionally possess
some power of regeneration, as in the lowest animals. (10. I have given
the evidence on this head in my 'Variation of Animals and Plants under
Domestication,' vol. ii. page 15, and more could be added.)

The whole process of that most important function, the reproduction of the
species, is strikingly the same in all mammals, from the first act of
courtship by the male (11. Mares e diversis generibus Quadrumanorum sine
dubio dignoscunt feminas humanas a maribus. Primum, credo, odoratu, postea
aspectu. Mr. Youatt, qui diu in Hortis Zoologicis (Bestiariis) medicus
animalium erat, vir in rebus observandis cautus et sagax, hoc mihi
certissime probavit, et curatores ejusdem loci et alii e ministris
confirmaverunt. Sir Andrew Smith et Brehm notabant idem in Cynocephalo.
Illustrissimus Cuvier etiam narrat multa de hac re, qua ut opinor, nihil
turpius potest indicari inter omnia hominibus et Quadrumanis communia.
Narrat enim Cynocephalum quendam in furorem incidere aspectu feminarum
aliquarem, sed nequaquam accendi tanto furore ab omnibus. Semper eligebat
juniores, et dignoscebat in turba, et advocabat voce gestuque.), to the
birth and nurturing of the young. Monkeys are born in almost as helpless a
condition as our own infants; and in certain genera the young differ fully
as much in appearance from the adults, as do our children from their
full-grown parents. (12. This remark is made with respect to Cynocephalus
and the anthropomorphous apes by Geoffroy Saint-Hilaire and F. Cuvier,
'Histoire Nat. des Mammiferes,' tom. i. 1824.) It has been urged by some
writers, as an important distinction, that with man the young arrive at
maturity at a much later age than with any other animal: but if we look to
the races of mankind which inhabit tropical countries the difference is not
great, for the orang is believed not to be adult till the age of from ten
to fifteen years. (13. Huxley, 'Man's Place in Nature,' 1863, p. 34.)
Man differs from woman in size, bodily strength, hairiness, etc., as well
as in mind, in the same manner as do the two sexes of many mammals. So
that the correspondence in general structure, in the minute structure of
the tissues, in chemical composition and in constitution, between man and
the higher animals, especially the anthropomorphous apes, is extremely
close.

EMBRYONIC DEVELOPMENT.

[Fig. 1. Shows a human embryo, from Ecker, and a dog embryo, from
Bischoff. Labelled in each are:

a. Fore-brain, cerebral hemispheres, etc.
b. Mid-brain, corpora quadrigemina.
c. Hind-brain, cerebellum, medulla oblongata.
d. Eye.
e. Ear.
f. First visceral arch.
g. Second visceral arch.
H. Vertebral columns and muscles in process of development.
i. Anterior extremities.
K. Posterior extremities.
L. Tail or os coccyx.]

Man is developed from an ovule, about the 125th of an inch in diameter,
which differs in no respect from the ovules of other animals. The embryo
itself at a very early period can hardly be distinguished from that of
other members of the vertebrate kingdom. At this period the arteries run
in arch-like branches, as if to carry the blood to branchiae which are not
present in the higher Vertebrata, though the slits on the sides of the neck
still remain (see f, g, fig. 1), marking their former position. At a
somewhat later period, when the extremities are developed, "the feet of
lizards and mammals," as the illustrious Von Baer remarks, "the wings and
feet of birds, no less than the hands and feet of man, all arise from the
same fundamental form." It is, says Prof. Huxley (14. 'Man's Place in
Nature,' 1863, p. 67.), "quite in the later stages of development that the
young human being presents marked differences from the young ape, while the
latter departs as much from the dog in its developments, as the man does.
Startling as this last assertion may appear to be, it is demonstrably
true."

As some of my readers may never have seen a drawing of an embryo, I have
given one of man and another of a dog, at about the same early stage of
development, carefully copied from two works of undoubted accuracy. (15.
The human embryo (upper fig.) is from Ecker, 'Icones Phys.,' 1851-1859,
tab. xxx. fig. 2. This embryo was ten lines in length, so that the drawing
is much magnified. The embryo of the dog is from Bischoff,
'Entwicklungsgeschichte des Hunde-Eies,' 1845, tab. xi. fig. 42B. This
drawing is five times magnified, the embryo being twenty-five days old.
The internal viscera have been omitted, and the uterine appendages in both
drawings removed. I was directed to these figures by Prof. Huxley, from
whose work, 'Man's Place in Nature,' the idea of giving them was taken.
Haeckel has also given analogous drawings in his 'Schopfungsgeschichte.')

After the foregoing statements made by such high authorities, it would be
superfluous on my part to give a number of borrowed details, shewing that
the embryo of man closely resembles that of other mammals. It may,
however, be added, that the human embryo likewise resembles certain low
forms when adult in various points of structure. For instance, the heart
at first exists as a simple pulsating vessel; the excreta are voided
through a cloacal passage; and the os coccyx projects like a true tail,
"extending considerably beyond the rudimentary legs." (16. Prof. Wyman in
'Proceedings of the American Academy of Sciences,' vol. iv. 1860, p. 17.)
In the embryos of all air-breathing vertebrates, certain glands, called the
corpora Wolffiana, correspond with, and act like the kidneys of mature
fishes. (17. Owen, 'Anatomy of Vertebrates,' vol. i. p. 533.) Even at a
later embryonic period, some striking resemblances between man and the
lower animals may be observed. Bischoff says that "the convolutions of the
brain in a human foetus at the end of the seventh month reach about the
same stage of development as in a baboon when adult." (18. 'Die
Grosshirnwindungen des Menschen,' 1868, s. 95.) The great toe, as
Professor Owen remarks (19. 'Anatomy of Vertebrates,' vol. ii. p. 553.),
"which forms the fulcrum when standing or walking, is perhaps the most
characteristic peculiarity in the human structure;" but in an embryo, about
an inch in length, Prof. Wyman (20. 'Proc. Soc. Nat. Hist.' Boston, 1863,
vol. ix. p. 185.) found "that the great toe was shorter than the others;
and, instead of being parallel to them, projected at an angle from the side
of the foot, thus corresponding with the permanent condition of this part
in the quadrumana." I will conclude with a quotation from Huxley (21.
'Man's Place in Nature,' p. 65.) who after asking, does man originate in a
different way from a dog, bird, frog or fish? says, "the reply is not
doubtful for a moment; without question, the mode of origin, and the early
stages of the development of man, are identical with those of the animals
immediately below him in the scale: without a doubt in these respects, he
is far nearer to apes than the apes are to the dog."

RUDIMENTS.

This subject, though not intrinsically more important than the two last,
will for several reasons be treated here more fully. (22. I had written a
rough copy of this chapter before reading a valuable paper, "Caratteri
rudimentali in ordine all' origine dell' uomo" ('Annuario della Soc. d.
Naturalisti,' Modena, 1867, p. 81), by G. Canestrini, to which paper I am
considerably indebted. Haeckel has given admirable discussions on this
whole subject, under the title of Dysteleology, in his 'Generelle
Morphologie' and 'Schopfungsgeschichte.') Not one of the higher animals
can be named which does not bear some part in a rudimentary condition; and
man forms no exception to the rule. Rudimentary organs must be
distinguished from those that are nascent; though in some cases the
distinction is not easy. The former 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, on the other hand, though not fully developed, 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.

The chief agents in causing organs to become rudimentary seem to have been
disuse at that period of life when the organ is chiefly used (and this is
generally during maturity), and also inheritance at a corresponding period
of life. The term "disuse" does not relate merely to the lessened action
of muscles, but includes a diminished flow of blood to a part or organ,
from being subjected to fewer alternations of pressure, or from becoming in
any way less habitually active. Rudiments, however, may occur in one sex
of those parts which are normally present in the other sex; and such
rudiments, as we shall hereafter see, have often originated in a way
distinct from those here referred to. In some cases, organs have been
reduced by means of natural selection, from having become injurious to the
species under changed habits of life. The process of reduction is probably
often aided through the two principles of compensation and economy of
growth; but the later stages of reduction, after disuse has done all that
can fairly be attributed to it, and when the saving to be effected by the
economy of growth would be very small (23. Some good criticisms on this
subject have been given by Messrs. Murie and Mivart, in 'Transact.
Zoological Society,' 1869, vol. vii. p. 92.), are difficult to understand.
The final and complete suppression of a part, already useless and much
reduced in size, in which case neither compensation nor economy can come
into play, is perhaps intelligible by the aid of the hypothesis of
pangenesis. But as the whole subject of rudimentary organs has been
discussed and illustrated in my former works (24. 'Variation of Animals
and Plants under Domestication,' vol. ii pp. 317 and 397. See also 'Origin
of Species,' 5th Edition p. 535.), I need here say no more on this head.

Rudiments of various muscles have been observed in many parts of the human
body (25. For instance, M. Richard ('Annales des Sciences Nat.,' 3rd
series, Zoolog. 1852, tom. xviii. p. 13) describes and figures rudiments of
what he calls the "muscle pedieux de la main," which he says is sometimes
"infiniment petit." Another muscle, called "le tibial posterieur," is
generally quite absent in the hand, but appears from time to time in a more
or less rudimentary condition.); and not a few muscles, which are regularly
present in some of the lower animals can occasionally be detected in man in
a greatly reduced condition. Every one must have noticed the power which
many animals, especially horses, possess of moving or twitching their skin;
and this is effected by the panniculus carnosus. Remnants of this muscle
in an efficient state are found in various parts of our bodies; for
instance, the muscle on the forehead, by which the eyebrows are raised.
The platysma myoides, which is well developed on the neck, belongs to this
system. Prof. Turner, of Edinburgh, has occasionally detected, as he
informs me, muscular fasciculi in five different situations, namely in the
axillae, near the scapulae, etc., all of which must be referred to the
system of the panniculus. He has also shewn (26. Prof. W. Turner,
'Proceedings of the Royal Society of Edinburgh,' 1866-67, p. 65.) that the
musculus sternalis or sternalis brutorum, which is not an extension of the
rectus abdominalis, but is closely allied to the panniculus, occurred in
the proportion of about three per cent. in upwards of 600 bodies: he adds,
that this muscle affords "an excellent illustration of the statement that
occasional and rudimentary structures are especially liable to variation in
arrangement."

Some few persons have the power of contracting the superficial muscles on
their scalps; and these muscles are in a variable and partially rudimentary
condition. M. A. de Candolle has communicated to me a curious instance of
the long-continued persistence or inheritance of this power, as well as of
its unusual development. He knows a family, in which one member, the
present head of the family, could, when a youth, pitch several heavy books
from his head by the movement of the scalp alone; and he won wagers by
performing this feat. His father, uncle, grandfather, and his three
children possess the same power to the same unusual degree. This family
became divided eight generations ago into two branches; so that the head of
the above-mentioned branch is cousin in the seventh degree to the head of
the other branch. This distant cousin resides in another part of France;
and on being asked whether he possessed the same faculty, immediately
exhibited his power. This case offers a good illustration how persistent
may be the transmission of an absolutely useless faculty, probably derived
from our remote semi-human progenitors; since many monkeys have, and
frequently use the power, of largely moving their scalps up and down. (27.
See my 'Expression of the Emotions in Man and Animals,' 1872, p. 144.)

The extrinsic muscles which serve to move the external ear, and the
intrinsic muscles which move the different parts, are in a rudimentary
condition in man, and they all belong to the system of the panniculus; they
are also variable in development, or at least in function. I have seen one
man who could draw the whole ear forwards; other men can draw it upwards;
another who could draw it backwards (28. Canestrini quotes Hyrtl.
('Annuario della Soc. dei Naturalisti,' Modena, 1867, p. 97) to the same
effect.); and from what one of these persons told me, it is probable that
most of us, by often touching our ears, and thus directing our attention
towards them, could recover some power of movement by repeated trials. The
power of erecting and directing the shell of the ears to the various points
of the compass, is no doubt of the highest service to many animals, as they
thus perceive the direction of danger; but I have never heard, on
sufficient evidence, of a man who possessed this power, the one which might
be of use to him. The whole external shell may be considered a rudiment,
together with the various folds and prominences (helix and anti-helix,
tragus and anti-tragus, etc.) which in the lower animals strengthen and
support the ear when erect, without adding much to its weight. Some
authors, however, suppose that the cartilage of the shell serves to
transmit vibrations to the acoustic nerve; but Mr. Toynbee (29. 'The
Diseases of the Ear,' by J. Toynbee, F.R.S., 1860, p. 12. A distinguished
physiologist, Prof. Preyer, informs me that he had lately been
experimenting on the function of the shell of the ear, and has come to
nearly the same conclusion as that given here.), after collecting all the
known evidence on this head, concludes that the external shell is of no
distinct use. The ears of the chimpanzee and orang are curiously like
those of man, and the proper muscles are likewise but very slightly
developed. (30. Prof. A. Macalister, 'Annals and Magazine of Natural
History,' vol. vii. 1871, p. 342.) I am also assured by the keepers in the
Zoological Gardens that these animals never move or erect their ears; so
that they are in an equally rudimentary condition with those of man, as far
as function is concerned. Why these animals, as well as the progenitors of
man, should have lost the power of erecting their ears, we cannot say. It
may be, though I am not satisfied with this view, that owing to their
arboreal habits and great strength they were but little exposed to danger,
and so during a lengthened period moved their ears but little, and thus
gradually lost the power of moving them. This would be a parallel case
with that of those large and heavy birds, which, from ihabiting oceanic
islands, have not been exposed to the attacks of beasts of prey, and have
consequently lost the power of using their wings for flight. The inability
to move the ears in man and several apes is, however, partly compensated by
the freedom with which they can move the head in a horizontal plane, so as
to catch sounds from all directions. It has been asserted that the ear of
man alone possesses a lobule; but "a rudiment of it is found in the
gorilla" (31. Mr. St. George Mivart, 'Elementary Anatomy,' 1873, p. 396.);
and, as I hear from Prof. Preyer, it is not rarely absent in the negro.

[Fig. 2. Human Ear, modelled and drawn by Mr. Woolner. The projecting
point is labelled a.]

Copyright (c) 2007. fullstories.net. All rights reserved.