History of the World/History of the World (Bureau Development, Inc.)(1992).BIN/dp/0105/01058.txt

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$Title{Descent Of Man, The
Chapter 2.1}
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$Author{Darwin, Charles}
$Affiliation{}
$Subject{footnote
animals
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conditions
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body
ii
variation
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$Date{1874}
$Log{}
Title:       Descent Of Man, The
Book:        Part I: The Descent Or Origin Of Man
Author:      Darwin, Charles
Date:        1874

Chapter 2.1

     Variability of body and mind in man - Inheritance - Causes of variability
- Laws of variation the same in man as in the lower animals - Direct action of
the conditions of life - Effects of the increased use and disuse of parts -
Arrested development - Reversion - Correlated variation - Rate of increase -
Checks to increase - Natural selection - Man the most dominant animal in the
world - Importance of his corporeal structure - The causes which have led to
his becoming erect - Consequent changes of structure -Decrease in size of the
canine teeth - Increased size and altered shape of the skull - Nakedness -
Absence of a tail - Defenceless condition of man.

     It is manifest that man is now subject to much variability. No two
individuals of the same race are quite alike.  We may compare millions of
faces, and each will be distinct.  There is an equally great amount of
diversity in the proportions and dimensions of the various parts of the body;
the length of the legs being one of the most variable points. ^59 Although in
some quarters of the world an elongated skull, and in other quarters a short
skull prevails, yet there is great diversity of shape even within the limits
of the same race, as with the aborigines of America and South Australia - the
latter a race "probably as pure and homogeneous in blood, customs, and
language as any in existence" -and even with the inhabitants of so confined an
area as the Sandwich Islands. ^60 An eminent dentist assures me that there is
nearly as much diversity in the teeth as in the features.  The chief arteries
so frequently run in abnormal courses, that it has been found useful for
surgical purposes to calculate from 1040 corpses how often each course
prevails. ^61 The muscles are eminently variable: thus those of the foot were
found by Prof. Turner ^62 not to be strictly alike in any two out of fifty
bodies; and in some the deviations were considerable.  He adds, that the power
of performing the appropriate movements must have been modified in accordance
with the several deviations.  Mr. J. Wood has recorded ^63 the occurrence of
295 muscular variations in thirty-six subjects, and in another set of the same
number no less than 558 variations, those occurring on both sides of the body
being only reckoned as one.  In the last set, not one body out of the
thirty-six was "found totally wanting in departures from the standard
descriptions of the muscular system given in anatomical text books." A single
body presented the extraordinary number of twenty-five distinct abnormalities.
The same muscle sometimes varies in many ways: thus Prof. Macalister describes
^64 no less than twenty distinct variations in the palmaris accessorius.

[Footnote 59: "Investigations in Military and Anthropolog.  Statistics of
American Soldiers," by B. A. Gould, 1869, p. 256.]

[Footnote 60: With respect to the "Cranial forms of the American Aborigines,"
see Dr. Aitken Meigs in "Proc. Acad. Nat. Sci.," Philadelphia, May, 1868.  On
the Australians, see Huxley, in Lyell's "Antiquity of Man," 1863, p. 87.  On
the Sandwich Islanders, Prof. J. Wyman, "Observations on Crania," Boston,
1868, p. 18.]

[Footnote 61: "Anatomy of the Arteries," by R. Quain.  Preface, vol. i, 1844.]

[Footnote 62: "Transact. Royal Soc. Edinburgh," vol. xxiv, pp. 175, 189.]

[Footnote 63: "Proc. Royal Soc.," 1867, p. 544; also 1868, pp. 483, 524. There
is a previous paper, 1866, p. 229.]

[Footnote 64: "Proc. R. Irish Academy," vol. x, 1868, p. 141.]

     The famous old anatomist, Wolff, ^65 insists that the internal viscera
are more variable than the external parts: Nulla particula est quoe non aliter
et aliter in aliis se habeat hominibus.  He has even written a treatise on the
choice of typical examples of the viscera for representation.  A discussion of
the beau-ideal of the liver, lungs, kidneys, etc., as of the human face
divine, sounds strange in our ears.

[Footnote 65: "Act. Acad. St. Petersburg," 1778, part ii, p. 217.]

     The variability or diversity of the mental faculties in men of the same
race, not to mention the greater differences between the men of distinct
races, is so notorious that not a word need here be said.  So it is with the
lower animals.  All who have had charge of menageries admit this fact, and we
see it plainly in our dogs and other domestic animals. Brehm especially
insists that each individual monkey of those which he kept tame in Africa had
its own peculiar disposition and temper: he mentions one baboon remarkable for
its high intelligence; and the keepers in the Zoological Gardens pointed out
to me a monkey, belonging to the New World division, equally remarkable for
intelligence.  Rengger, also, insists on the diversity in the various mental
characters of the monkeys of the same species which he kept in Paraguay; and
this diversity, as he adds, is partly innate, and partly the result of the
manner in which they have been treated or educated. ^66

[Footnote 66: Brehm, "Thierleben," B. i, s. 58, 87.  Rengger, "Saugethiere von
Paraguay," s. 57.]

     I have elsewhere ^67 so fully discussed the subject of Inheritance, that
I need here add hardly any thing.  A greater number of facts have been
collected with respect to the transmission of the most trifling, as well as of
the most important characters in man, than in any of the lower animals; though
the facts are copious enough with respect to the latter. So in regard to
mental qualities, their transmission is manifest in our dogs, horses, and
other domestic animals.  Besides special tastes and habits, general
intelligence, courage, bad and good temper, etc., are certainly transmitted.
With man we see similar facts in almost every family; and we now know, through
the admirable labors of Mr. Galton ^68 that genius which implies a wonderfully
complex combination of high faculties, tends to be inherited; and, on the
other hand, it is too certain that insanity and deteriorated mental powers
likewise run in families.

[Footnote 67: "Variation of Animals and Plants under Domestication," vol. ii,
chap. xii.]

[Footnote 68: "Hereditary Genius: an Inquiry into its Laws and Consequences,"
1869.]

     With respect to the causes of variability, we are in all cases very
ignorant; but we can see that in man as in the lower animals, they stand in
some relation to the conditions to which each species has been exposed during
several generations.  Domesticated animals vary more than those in a state of
nature; and this is apparently due to the diversified and changing nature of
the conditions to which they have been subjected.  In this respect the
different races of man resemble domesticated animals, and so do the
individuals of the same race, when inhabiting a very wide area, like that of
America.  We see the influence of diversified conditions in the more civilized
nations; for the members belonging to different grades of rank, and following
different occupations, present a greater range of character than do the
members of barbarous nations.  But the uniformity of savages has often been
exaggerated, and in some cases can hardly be said to exist. ^69 It is,
nevertheless, an error to speak of man, even if we look only to the conditions
to which he has been exposed, as "far more domesticated" ^70 than any other
animal.  Some savage races, such as the Australians, are not exposed to more
diversified conditions than are many species which have a wide range.  In
another and much more important respect, man differs widely from any strictly
domesticated animal; for his breeding has never long been controlled, either
by methodical or unconscious selection.  No race or body of men has been so
completely subjugated by other men, as that certain individuals should be
preserved, and thus unconsciously selected, from somehow excelling in utility
to their masters.  Nor have certain male and female individuals been
intentionally picked out and matched, except in the well-known case of the
Prussian grenadiers; and in this case man obeyed, as might have been expected,
the law of methodical selection; for it is asserted that many tall men were
reared in the villages inhabited by the grenadiers and their tall wives.  In
Sparta, also, a form of selection was followed, for it was enacted that all
children should be examined shortly after birth; the well-formed and vigorous
being preserved, the others left to perish. ^71

[Footnote 69: Mr. Bates remarks ("The Naturalist on the Amazons," 1863, vol.
ii, p. 159), with respect to the Indians of the same South American tribe, "No
two of them were at all similar in the shape of the head; one man had an oval
visage with fine features, and another was quite Mongolian in breadth and
prominence of cheek, spread of nostrils, and obliquity of eyes."]

[Footnote 70: Blumenbach, "Treatises on Anthropolog.," Eng. translat., 1865,
p. 205.]

[Footnote 71: Mitford's "History of Greece," vol. i, p. 282.  It appears also
from a passage in Xenophon's "Memorabilia," B. ii, 4 (to which my attention
has been called by the Rev. J. N. Hoare), that it was a well recognized
principle with the Greeks, that men ought to select their wives with a view to
the health and vigor of their children.  The Grecian poet, Theognis, who lived
550 B.C. clearly saw how important selection, if carefully applied, would be
for the improvement of mankind.  He saw, likewise, that wealth often checks
the proper action of sexual selection. He thus writes:

     "With kine and horses, Kurnus!  we proceed
     By reasonable rules, and choose a breed
     For profit and increase, at any price;
     Of a sound stock, without defect or vice.
     But, in the daily matches that we make,
     The price is every thing: for money's sake,
     Men marry: women are in marriage given
     The churl or ruffian, that in wealth has thriven,
     May match his offspring with the proudest race:
     Thus every thing is mix'd, noble and base!
     If then in outward manner, form, and mind,
     You find us a degraded, motley kind,
     Wonder no more, my friend!  the cause is plain.
     And to lament the consequence is vain."

     (The works of J. Hookham Frere, vol. ii, 1872, p. 334.)]

     If we consider all the races of man as forming a single species, his
range is enormous; but some separate races, as the Americans and Polynesians,
have very wide ranges.  It is a well-known law that widely ranging species are
much more variable than species with restricted ranges; and the variability of
man may with mere truth be compared with that of widely ranging species, than
with that of domesticated animals.

     Not only does variability appear to be induced in man and the lower
animals by the same general causes, but in both the same parts of the body are
affected in a closely analogous manner.  This has been proved in such full
detail by Godron and Quatrefages, that I need here only refer to their works.
^72 Monstrosities, which graduate into slight variations, are likewise so
similar in man and the lower animals, that the same classification and the
same terms can be used for both, as has been shown by Isidore Geoffroy
St.-Hilaire. ^73 In my work on the variation of domestic animals, I have
attempted to arrange in a rude fashion the laws of variation under the
following heads: The direct and definite action of changed conditions, as
exhibited by all or nearly all the individuals of the same species, varying in
the same manner under the same circumstances.  The effects of the
long-continued use or disuse of parts. The cohesion of homologous parts.  The
variability of multiple parts. Compensation of growth; but of this law I have
found no good instance in the case of man.  The effects of the mechanical
pressure of one part on another; as of the pelvis on the cranium of the infant
in the womb. Arrests of development, leading to the diminution or suppression
of parts.  The reappearance of long-lost characters through reversion.  And
lastly, correlated variation.  And these so-called laws apply equally to man
and the lower animals; and most of them even to plants.  It would be
superfluous here to discuss all of them; ^74 but several are so important,
that they must be treated at considerable length.

[Footnote 72: Godron, "De l'Espece," 1859, tom. ii, livre 3. Quatrefages,
"Unite de l'Espece Humaine," 1861.  Also Lectures on Anthropology, given in
the "Revue des Cours Scientifiques," 1866-1868.]

[Footnote 73: "Hist. Gen. et Part. des Anomalies de l'Organisation," in three
volumes, tom. i, 1832.]

[Footnote 74: I have fully discussed these laws in my "Variation of Animals
and Plants under Domestication," vol. ii, chap. xxii and xxiii. M. J. P.
Durand has lately (1868) published a valuable essay "De l'Influence des
Milieux," etc.  He lays much stress, in the case of plants, on the nature of
the soil.]

     The Direct and Definite Action of Changed Conditions. - This is a most
perplexing subject.  It cannot be denied that changed conditions produce some,
and occasionally a considerable effect, on organisms of all kinds; and it
seems at first probable that if sufficient time were allowed this would be the
invariable result. But I have failed to obtain clear evidence in favor of this
conclusion; and valid reasons may be urged on the other side, at least as far
as the innumerable structures are concerned which are adapted for special
ends.  There can, however, be no doubt that changed conditions induce an
almost indefinite amount of fluctuating variability, by which the whole
organization is rendered in some degree plastic.

     In the United States, above 1,000,000 soldiers, who served in the late
war, were measured, and the States in which they were born and reared were
recorded. ^75 From this astonishing number of observations it is proved that
local influences of some kind act directly on stature; and we further learn
that "the State where the physical growth has in great measure taken place,
and the State of birth, which indicates the ancestry, seem to exert a marked
influence on the stature." For instance, it is established, "that residence in
the Western States, during the years of growth, tends to produce increase of
stature." On the other hand, it is certain that with sailors, their life
delays growth, as shown "by the great difference between the statures of
soldiers and sailors at the ages of seventeen and eighteen years." Mr. B. A.
Gould endeavored to ascertain the nature of the influences which thus act on
stature; but he arrived only at negative results, namely, that they did not
relate to climate, the elevation of the land, soil, nor even "in any
controlling degree" to the abundance or the need of the comforts of life.
This latter conclusion is directly opposed to that arrived at by Villerme,
from the statistics of the height of the conscripts in different parts of
France.  When we compare the differences in stature between the Polynesian
chiefs and the lower orders within the same islands, or between the
inhabitants of the fertile volcanic and low barren coral islands of the same
ocean, ^76 or again between the Fuegians on the eastern and western shores of
their country, where the means of subsistence are very different, it is
scarcely possible to avoid the conclusion that better food and greater comfort
do influence stature. But the preceding statements show how difficult it is to
arrive at any precise result.  Dr. Beddoe has lately proved that, with the
inhabitants of Britain, residence in towns and certain occupations have a
deteriorating influence on height; and he infers that the result is to a
certain extent inherited, as is likewise the case in the United States. Dr.
Beddoe further believes that wherever a "race attains its maximum of physical
development, it rises highest in energy and moral vigor." ^77

[Footnote 75: "Investigations in Military and Anthrop. Statistics," etc.,
1869, by B. A. Gould, pp. 93, 107, 126, 131, 134.]

[Footnote 76: For the Polynesians, see Prichard's "Physical Hist. of Mankind,"
vol. v, 1847, pp. 145, 283.  Also Godron, "De l'Espece," tom. ii, p. 289.
There is also a remarkable difference in appearance between the closely allied
Hindoos inhabiting the Upper Ganges and Bengal; see Elphinstone's "History of
India," vol. i, p. 324.]

[Footnote 77: "Memoirs, Anthropolog. Soc.," vol. iii, 1867-69, pp. 561, 565,
567.]

     Whether external conditions produce any other direct effect on man is not
known.  It might have been expected that differences of climate would have had
a marked influence, inasmuch as the lungs and kidneys are brought into
activity under a low temperature, and the liver and skin under a high one. ^78
It was formerly thought that the color of the skin and the character of the
hair were determined by light or heat; and although it can hardly be denied
that some effect is thus produced, almost all observers now agree that the
effect has been very small, even after exposure during many ages.  But this
subject will be more properly discussed when we treat of the different races
of mankind.  With our domestic animals there are grounds for believing that
cold and damp directly affect the growth of the hair; but I have not met with
any evidence on this head in the case of man.

[Footnote 78: Dr. Brakenridge, "Theory of Diathesis," "Medical Times," June
19, and July 17, 1869.]

     Effects of the Increased Use and Disuse of Parts. - It is well known that
use strengthens the muscles in the individual, and complete disuse, or the
destruction of the proper nerve, weakens them.  When the eye is destroyed, the
optic nerve often becomes atrophied.  When an artery is tied, the lateral
channels increase not only in diameter, but in the thickness and strength of
their coats.  When one kidney ceases to act from disease, the other increases
in size, and does double work.  Bones increase not only in thickness, but in
length, from carrying a greater weight. ^79 Different occupations, habitually
followed, lead to changed proportions in various parts of the body.  Thus it
was ascertained by the United States Commission ^80 that the legs of the
sailors employed in the late war were longer by 0.217 of an inch than those of
the soldiers, though the sailors were on an average shorter men; while their
arms were shorter by 1.09 of an inch, and therefore, out of proportion,
shorter in relation to their lesser height.  This shortness of the arms is
apparently due to their greater use, and is an unexpected result: but sailors,
chiefly use their arms in pulling, and not in supporting weights.  With
sailors, the girth of the neck and the depth of the instep are greater, while
the circumference of the chest, waist, and hips is less than in soldiers.

[Footnote 79: I have given authorities for these several statements in my
"Variation of Animals under Domestication," vol. ii, pp. 297-300.  Dr. Jaeger,
"Ueber das Langenwachsthum der Knochen," "Jenaischen Zeitschrift," B. v, Heft.
i.]

[Footnote 80: "Investigations," etc.  By B. A. Gould, 1869, p. 288.]

     Whether the several foregoing modifications would become hereditary, if
the same habits of life were followed during many generations, is not known,
but it is probable.  Rengger ^81 attributes the thin legs and thick arms of
the Payaguas Indians to successive generations having passed nearly their
whole lives in canoes, with their lower extremities motionless.  Other writers
have come to a similar conclusion in analogous cases.  According to Cranz, ^82
who lived for a long time with the Esquimaux, "the natives believe that
ingenuity and dexterity in seal-catching (their highest art and virtue) is
hereditary; there is really something in it, for the son of a celebrated
seal-catcher will distinguish himself, though he lost his father in
childhood." But in this case it is mental aptitude, quite as much as bodily
structure, which appears to be inherited.  It is asserted that the hands of
English laborers are at birth larger than those of the gentry. ^83 From the
correlation which exists, at least in some cases, ^84 between the development
of the extremities and of the jaws, it is possible that in those classes which
do not labor much with their hands and feet, the jaws would be reduced in size
from this cause.  That they are generally smaller in refined and civilized men
that in hard-working men or savages, is certain.  But with savages, as Mr.
Herbert Spencer ^85 has remarked, the greater use of the jaws in chewing
coarse, uncooked food, would act in a direct manner on the masticatory
muscles, and on the bones to which they are attached.  In infants, long before
birth, the skin on the soles of the feet is thicker than on any other part of
the body; ^86 and it can hardly be doubted that this is due to the inherited
effects of pressure during a long series of generations.

[Footnote 81: "Saugethiere von Paraguay," 1830, s. 4.]

[Footnote 82: "History of Greenland," Eng. translat., 1767, vol. i, p. 230.]

[Footnote 83: "Intermarriage." By Alex. Walker, 1838, p. 377.]

[Footnote 84: "The Variation of Animals under Domestication," vol. i, p. 173.]

[Footnote 85: "Principles of Biology," vol. i, p. 455.]

[Footnote 86: Paget, "Lectures on Surgical Pathology," vol. ii, 1853, p. 209.]

     It is familiar to every one that watchmakers and engravers are liable to
be short-sighted, while men living much out of doors, and especially savages,
are generally long-sighted. ^87 Short-sight and long-sight certainly tend to
be inherited. ^88 The inferiority of Europeans, in comparison with savages, in
eyesight and in the other senses, is no doubt the accumulated and transmitted
effect of lessened use during many generations; for Rengger ^89 states that he
has repeatedly observed Europeans, who had been brought up and spent their
whole lives with the wild Indians, who nevertheless did not equal them in the
sharpness of their senses.  The same naturalist observes that the cavities in
the skull for the reception of the several sense-organs are larger in the
American aborigines than in Europeans; and this probably indicates a
corresponding difference in the dimensions of the organs themselves.
Blumenbach has also remarked on the large size of the nasal cavities in the
skulls of the American aborigines, and connects this fact with their
remarkably acute power of smell.  The Mongolians of the plains of Northern
Asia, according to Pallas, have wonderfully perfect senses; and Prichard
believes that the great breadth of their skulls across the zygomas follows
from their highly developed sense-organs. ^90

[Footnote 87: It is a singular and unexpected fact that sailors are inferior
to landsmen in their mean distance of distinct vision.  Dr. B. A. Gould
("Sanitary Memoirs of the War of the Rebellion," 1869, p. 530), has proved
this to be the case; and he accounts for it by the ordinary range of vision in
sailors being "restricted to the length of the vessel and the height of the
masts."]

[Footnote 88: "The Variation of Animals under Domestication," vol. i, p. 8.]

[Footnote 89: "Saugethiere von Paraguay," s. 8, 10.  I have had good
opportunities for observing the extraordinary power of eyesight in the
Fuegians.  See also Lawrence ("Lectures on Physiology," etc., 1822, p. 404) on
this same subject.  M. Giraud-Teulon has recently collected ("Revue des Cours
Scientifiques," 1870, p. 625) a large and valuable body of evidence proving
that the cause of short-sight, "C'est le travail assidu, de pres."]

[Footnote 90: Prichard, "Phys. Hist. of Mankind," on the authority of
Blumenbach, vol. i, 1851, p. 311; for the statement by Pallas, vol. iv, 1844,
p. 407.]