ANTIQUITY OF MAN.
I do not propose to bestow any large amount of space upon the enumeration
of the palæontological evidence of the antiquity of man. The works of the
various eminent authors who have devoted themselves to the special
consideration of this subject exhaust all that can be said upon it with
our present data, and to these I must refer the reader who is desirous of
acquainting himself critically with its details, confining myself to a few
general statements based on these labours.
In the early days of geological science when observers were few, great
groups of strata were arranged under an artificial classification, which,
while it has lost to a certain extent the specific value which it then
assumed to possess, is still retained for purposes of convenient
reference. Masters of the science acquired, so to say, a possessive
interest in certain regions of it, and the names of Sedgwick, Murchison,
Jukes, Phillips, Lyell, and others became, and will remain, inseparably
associated with the history of those great divisions of the materials of
the earth's crust, which, under the names of the Cambrian, Silurian,
Devonian, Carboniferous, and Tertiary formations, have become familiar to
us.
In those days, when observations were limited to a comparatively small
area, the lines separating most of these formations were supposed to be
hard and definite; forms of life which characterized one, were presumed to
have become entirely extinct before the inauguration of those which
succeeded them, and breaks in the stratigraphical succession appeared to
justify the opinion, held by a large and influential section, that great
cataclysms or catastrophes had marked the time when one age or formation
terminated and another commenced to succeed it.
By degrees, and with the increase of observers, both in England and in
every portion of the world, modifications of these views obtained; passage
beds were discovered, connecting by insensible gradations formations which
had hitherto been supposed to present the most abrupt separations;
transitional forms of life connecting them were unearthed; and an opinion
was advanced, and steadily confirmed, which at the present day it is
probable no one would be found to dispute, that not all in one place or
country, but discoverable in some part or other of the world, a perfect
sequence exists, from the very earliest formations of which we have any
cognizance, up to the alluvial and marine deposits in process of formation
at the present day.[71]
Correlatively it was deduced that the same phenomena of nature have been
in action since the earliest period when organic existence can be
affirmed. The gradual degradation of pre-existing continents by normal
destructive agencies, the upheaval and subsidence of large areas, the
effusion from volcanic vents, into the air or sea, of ashes and lavas, the
action of frost and ice, of heat, rain, and sunshine--all these have acted
in the past as they are still acting before our eyes.
In earlier days, arguing from limited data, a progressive creation was
claimed which confined the appearance of the higher form of vertebrate
life to a successive and widely-stepped gradation.
Hugh Miller, and other able thinkers, noted with satisfaction the
appearance, first of fish, then of reptiles, next of birds and mammals,
and finally, as the crowning work of all, both geologically and actually,
quite recently of man.
This wonderful confirmation of the Biblical history of creation appealed
so gratefully to many, that it caused for a time a disposition to cramp
discovery, and even to warp the facts of science, in order to make them
harmonize with the statements of Revelation. The alleged proofs of the
existence of pre-historic man were for a long time jealously disputed, and
it was only by slow degrees that they were admitted, that the tenets of
the Darwinian school gained ground, and that the full meaning was
appreciated of such anomalies as the existence at the present day of
Ganoid fishes both in America and Europe, of true Palæozoic type, or of
Oolitic forms on the Australian continent and in the adjacent seas.
But step by step marvellous palæontological discoveries were made, and the
pillars which mark the advent of each great form of life have had to be
set back, until now no one would, I think, be entirely safe in affirming
that even in the Cambrian, the oldest of all fossiliferous formations,
vestiges of mammals, that is to say, of the highest forms of life, may
not at a future day be found, or that the records contained between the
Cambrian and the present day, may not in fact be but a few pages as
compared with the whole volume of the world's history.[72]
It is with the later of these records that we have to deal, in which
discoveries have been made sufficiently progressive to justify the
expectation that they have by no means reached their limit, and
sufficiently ample in themselves to open the widest fields for philosophic
speculation and deduction.
Before stating these, it may be premised that estimates have been
attempted by various geologists of the collective age of the different
groups of formations.[73] These are based on reasonings which for the most
part it is unnecessary to give in detail, in so much as these can scarcely
yet be considered to have passed the bounds of speculation, and very
different results can be arrived at by theorists according to the relative
importance which they attach to the data employed in the calculation.
Thus Mr. T. Mellard Reade, in a paper communicated to the Royal Society in
1878, concludes that the formation of the sedimentary strata must have
occupied at least six hundred million years: which he divides in round
numbers as follows:--
Millions of Years.
Laurentian, Cambrian, and Silurian 200
Old Red, Carboniferous, Permian, and New Red 200
Jurassic, Wealden, Cretaceous, Eocene, Miocene,
Pliocene, and Post Pliocene 200
---
600
He estimates the average thickness of the sedimentary crust of the earth
to be at least one mile, and from a computation of the proportion of
carbonate and sulphate of lime to materials held in suspension in various
river-waters from a variety of formations, infers that one-tenth of this
crust is calcareous.
He estimates the annual flow of water in all the great river-basins, the
proportion of rain-water running off the granitic and trappean rocks, the
percentage of lime in solution which they carry down, and arrives at the
conclusion that the minimum time requisite for the elimination of the
calcareous matter contained in the sedimentary crust of the earth, is at
least six hundred millions of years.
A writer in the _Gentleman's Magazine_[74] (Professor Huxley?), whose
article I am only able to quote at second-hand, makes an estimate which,
though much lower than the above, is still of enormous magnitude, as
follows:--
Feet. Years.
Laurentian 30,000 30,000,000
Cambrian 25,000 25,000,000
Silurian 6,000 6,000,000
Old Red and Devonian 10,000 10,000,000
Carboniferous 12,000 12,000,000
Secondary 10,000 10,000,000
Tertiary and Post Tertiary 1,000 1,000,000
Gaps and unrepresented strata 6,000 6,000,000
-----------
Total 100,000,000
Mr. Darwin, arguing upon Sir W. Thompson's estimate of a minimum of
ninety-eight and maximum of two hundred millions of years since the
consolidation of the crust, and on Mr. Croll's estimate of sixty millions,
as the time elapsed since the Cambrian period, considers that the latter
is quite insufficient to permit of the many and great mutations of life
which have certainly occurred since then. He judges from the small amount
of organic change since the commencement of the glacial epoch, and adds
that the previous one hundred and forty million years can hardly be
considered as sufficient for the development of the varied forms of life
which certainly existed towards the close of the Cambrian period.
On the other hand, Mr. Croll considers that it is utterly impossible that
the existing order of things, as regards our globe, can date so far back
as anything like five hundred millions of years, and, starting with
referring the commencement of the Glacial epoch to two hundred and fifty
thousand years ago, allows fifteen millions since the beginning of the
Eocene period, and sixty millions of years in all since the beginning of
the Cambrian period. He bases his arguments on the limit to the age of the
sun's heat as detailed by Sir William Thompson.
Sir Charles Lyell and Professor Haughton respectively estimated the
expiration of time from the commencement of the Cambrian at two hundred
and forty and two hundred millions of years, basing their calculations on
the rate of modification of the species of mollusca, in the one case, and
on the rate of formation of rocks and their maximum thickness, in the
other.
This, moreover, is irrespective of the vast periods during which life must
have existed, which on the development theory necessarily preceded the
Cambrian, and, according to Mr. Darwin, should not be less than in the
proportion of five to two.
In fine, one school of geologists and zoologists demand the maximum
periods quoted above, to account for the amount of sedimentary deposit,
and the specific developments which have occurred; the other considers the
periods claimed as requisite for these actions to be unnecessary, and to
be in excess of the limits which, according to their views, the physical
elements of the case permit.
Mr. Wallace, in reviewing the question, dwells on the probability of the
rate of geological changes having been greater in very remote times than
it is at present, and thus opens a way to the reconciliation of the
opposing views so far as one half the question is concerned.
Having thus adverted to the principles upon which various theorists have
in part based their attacks on the problem of the estimation of the
duration of geological ages, I may now make a few more detailed
observations upon those later periods during which man is, now, generally
admitted to have existed, and refer lightly to the earlier times which
some, but not all, geologists consider to have furnished evidences of his
presence.
I omit discussing the doubtful assertions of the extreme antiquity of man,
which come to us from American observers, such as are based on supposed
footprints in rocks of secondary age, figured in a semi-scientific and
exceedingly valuable popular journal. There are other theories which I
omit, both because they need further confirmation by scientific
investigators, and because they deal with periods so remote as to be
totally devoid of significance for the argument of this work.
Nor, up to the present time, are the evidences of the existence of man
during Miocene and Pliocene times admitted as conclusive. Professor
Capellini has discovered, in deposits recognised by Italian geologists as
of Pliocene age, cetacean bones, which are marked with incisions such as
only a sharp instrument could have produced, and which, in his opinion,
must be ascribed to human agency. To this view it is objected that the
incisions might have been made by the teeth of fishes, and further
evidence is waited for.
Not a few discoveries have been made, apparently extending the existence
of man to a much more remote antiquity, that of Miocene times. M. l'Abbé
Bourgeois has collected, from undoubted Miocene strata at Thenay, supposed
flint implements which he conceives to exhibit evidences of having been
fashioned by man, as well as stones showing in some cases traces of the
action of fire, and which he supposes to have been used as pot-boilers. M.
Carlos Ribeiro has made similar discoveries of worked flints and
quartzites in the Pliocene and Miocene of the Tagus; worked flint has been
found in the Miocene of Aurillac (Auvergne) by M. Tardy, and a cut rib of
_Halitherium fossile_, a Miocene species, by M. Delaunay at Pouancé.
Very divided opinions are entertained as to the interpretation of the
supposed implements discovered by M. l'Abbé Bourgeois. M. Quatrefages,
after a period of doubt, has espoused the view of their being of human
origin, and of Miocene age. "Since then," he says, "fresh specimens
discovered have removed my last doubts. A small knife or scraper, among
others, which shows a fine regular finish, can, in my opinion, only have
been shaped by man. Nevertheless, I do not blame those of my colleagues
who deny or still doubt. In such a matter there is no very great urgency,
and, doubtless, the existence of Miocene man will be proved, as that of
Glacial and Pliocene has been, by facts." Mr. Geikie, from whose
work--_Prehistoric Europe_--I have summarized the above statements, says,
in reference to this question: "There is unquestionably much force in what
M. Quatrefages says; nevertheless, most geologists will agree with him
that the question of man's Miocene age still remains to be demonstrated by
unequivocal evidence. At present, all that we can safely say is, that man
was probably living in Europe near the close of the Pliocene period, and
that he was certainly an occupant of our continent during glacial and
interglacial times."
Professor Marsh considers that the evidence, as it stands to-day, although
not conclusive, "seems to place the first appearance of man [in America]
in the Pliocene, and that the best proofs of this are to be found on the
Pacific coast." He adds: "During several visits to that region many facts
were brought to my knowledge which render this more than probable. Man, at
this time, was a savage, and was doubtless forced by the great volcanic
outbreaks to continue his migration. This was at first to the south, since
mountain chains were barriers on the east," and "he doubtless first came
across Behring's Straits."
I have hitherto assumed a certain acquaintance, upon the part of the
general reader, with the terms Eocene, Miocene, and Pliocene, happily
invented by Sir Charles Lyell to designate three of the four great
divisions of the Tertiary age. These, from their universal acceptation and
constant use, have "become familiar in our mouths as household words." But
it will be well, before further elaborating points in the history of these
groups, bearing upon our argument, to take into consideration their
subdivisions, and the equivalent or contemporary deposits composing them
in various countries. This can be most conveniently done by displaying
these, in descending order, in a tabular form, which I accordingly annex
below. This is the more desirable as there are few departments in
geological science which have received more attention than this; or in
which greater returns, in the shape of important and interesting
discoveries relative to man's existence, have been made.
Comparatively recent--comparatively, that is to say, with regard to the
vast æons that preceded them, but extending back over enormous spaces of
time when contrasted with the limited duration of written history,--they
embrace the period during which the mainly existing distribution of land
and ocean has obtained, and the present forms of life have appeared by
evolution from preceding species, or, as some few still maintain, by
separate and special creation.
THE TERTIARY OR CAINOZOIC AGE.
| | |
| | | 1. Recent }
| | | }
| |Man's | 2. Post Glacial }
| |range |Man's } Post }
|Man's |according |range, 3. Pleistocene or}Tertiary}
|range, |to |generally Quaternary } }
|according |Capellini,|admitted (including } }
|to l'Abbé |Marsh, | Glacial } }
|Bourgeois, |and | formation) } }
|Quatrefages,|others. | }
|and | 4. Newer Pliocene} }
|others. | }Pliocene}Tertiary
| +--------------------- 5. Older Pliocene} }or
| }Cainozoic
| 6. Upper Miocene } }
| }Miocene }
+---------------------------------- 7. Lower Miocene } }
}
8. Upper Eocene } }
} }
9. Middle do. }Eocene }
}
10. Lower do. }
PLIOCENE.
BRITAIN.
Norwich
P _Sand loam and gravel_
N l Marine, land, and fresh-water
e i shells
w o Many { Fusus striatus
e c shells { " antiquus
r e abundant, { Tunitella communis
n such as { Cardium edule, still existing
e in adjacent sea.
Norwich Crag.
P
O l { Red
l i {
d o Crag { White,
e c { or
r e { Coralline
n
e
MIOCENE.
-----------------------------------------------------------------------
BRITAIN. | FRANCE. | OTHER COUNTRIES OF |
| | EUROPE. |
| | |
{Ferruginous |Faluns of Touraine and |Edgehem beds } |
{ sands of | Bordeaux. |Diest sands }Belgium |
{ the North |_Dinotherium._ |Boldeberg beds} |
{ downs. | | |
{ |_Mastodon._ |Superga beds Italy |
U{_Terebratula | | |
P{ grandis._ |_Lamantine._ |Deposits of |
P{ | | Pikermé Greece |
E{ |Marine shells such as | with |
R{_Astarte | _Cypræa, Oliva_, |_Mastodon_ |
{ pyrula_ with | _Mitra, Conus_, |_Dinotherium_ |
M{ other shells | indicative of an |_Hipparion_ |
I{ common to | elevated temperature.|_Antelope_ |
O{ the Crag. |Fresh-water deposits of |_Camelopardalis_ |
C{ | Gers near the base of | |
E{ | the Pyrenees. |Beds above the} |
N{ |_Dinotherium giganteum._ | brown coal }Croatia |
E{ | | with Marine } |
{ |Mastodon angustidens. | shells } |
{ | |Fresh-water } |
{ | | Molasse at }Switzerland|
{ | | Oeningen } |
{ | |_Abundant } |
{ | | flora_ } |
| |Marine Molasse} |
| | |
{Hempstead beds,|Calcaire de la Beauce, |Kleyn Spawn } |
{ Isle of Wight.| fresh-water deposits of| beds and }Belgium |
{ | Auvergne, Sandstone, |Limburg beds } |
L{ | indusial limestone of | |
O{ | Cantal. | |
W{Marine and | | |
E{ fresh water |Fluvio-marine strata of |Marine and Fluvialite |
R{ _Voluta_ | Merignac and Bazas? | shells |
{ _Cyrena_ | | |
{ _Cerithium_ | | |
{ _&c. &c._ |_Cerithium, Pyrula, &c._ |Most of the } |
M{ | | Lignites are}Germany |
I{ | | Lower } |
O{Lignite |_Asterias limestone._ | Miocene } |
C{ deposits of | |Lower (fresh-water) |
E{ Bovey Tracey.| | Molasse |
N{ |_Nummulites._ | |
E{Numerous | | |
{ plants, such |Fresh-water strata of | |
{ as _Sequoia | Fontainebleau. | |
{ Nysa Annona_, |Grès de Fontainebleau | |
indicating a | (Marine). | |
sub-tropical | | |
climate. | | |
-----------------------------------------------------------------------
--------------------------
| INDIA. | AMERICA.
| |
| |
|Fresh-water |Fresh-water
| | deposits
|deposits of | in Oregon
| |
|Siwalik hills |
| |
|with |White river
|_Mastodon_ | group in
| | the Upper
|_Sivatherium_ | Missouri
| | Regions
|_Colossochelys_ |
| |
|_Rhinoceros_ |_Oreodont_
| |
|_Felis_ |_Brontether-
| | ium._
|_Machairodus_ |
| |Wind river
|_Equus_ | group
| |(Fresh-water
|_Hippotherium_ | deposit).
| |
|_Camelopardalis_|
| |
| |Miocene
| | deposits
| | over a
| | large part
| | of the
| | Atlantic
| | Tertiary
| | border.
| |
| |
| |In
| | California
| | Miocene
| | marine
| | deposits
| | reach
| | from 4,000
| | to 5,000
| | feet
| | in
| | thickness.
| |
| |
| |
--------------------------
EOCENE.
The subdivisions of the Eocene have been worked out in great detail in
Britain, France, and America. Those of most other countries have either
not yet been fully studied or their exact equivalence remains
undetermined.
---------------------------------------------------------------------
| |
BRITAIN. | FRANCE. |
| |
| |
| _Land and |
{ {Palæotherium | fresh-water |
{A1 Bembridge {Anoplotherium|Gypseous Series shells_ |
{ Series {Chæropotamus | of Montmatre _Many quadrupeds |
U{ { &c. | (4/5ths of them |
P{ | Perrissodactyls),|
P{A2 Osborne {Fresh-water |} Trionyx, Emys_ |
E{ Series { & brackish |} |
R{ { genera |}Calcaire Siliceux |
{ |} |
E{ {_Do._ |} |
O{ {_Emys_ |} |
C{A3 Headon {_Trionyx_ | |
E{ Series {_Alligator_ | |
N{ {_Crocodilus_ | |
E{ {_Lepidosteus_| |
{ | |
{A4 Barton {_Voluta_ | }|
{ Clay {_Mitra_ |Grès de Beauchamp _Nummulites_ }|
| }|
M{B1 Bagshot and _Cerithium_ |Calcaire Grossier _Miliolite }|
I{ Bracklesham _Voluta_ | limestone }|
D{ Sands and _Cowries_ | of minute }|
D{ Clays _Marine | Foraminifera._ }|
L{ Serpents_ | _Nummulites_ }|
E{ _Nummulites_ | _Cerithium_, }|
{ indicating a warm climate | &c. &c. }|
E{ with a vegetation | }|
O{ reminding the botanist of | }|
C{ the types of tropical | }|
E{ India and Australia |Soissonnais Sands _Nummulites_ }|
N{ | _Nerita_, &c. }|
E{B2 Wanting | &c. }|
| |
{C1 London Clay _Palms_ |Argile de Londres |
L{ and _Turtles_ | |
O{ Bognor beds _Sea Snakes_ | |
W{ _Crocodiles_ | |
E{ _Conus_, | |
R{ _Voluta_, | |
{ _Cyprina_, | |
{ _Nautilus_, | |
E{ and other shells | |
O{ indicating a semi- | |
C{ tropical climate | |
E{C2 Plastic and Mottled |Argile plastique _Fluviatile |
N{ Clays and Sands | and lignite shells_ |
E{ | _Large bird |
{C3 Thanet Sands _Pholadomya_ | Gastornis |
{ _Cyprina_, | Parisiensis_ |
{ &c. |Sables de Bracheux |
---------------------------------------------------------------------
------------------------------------------------------------------------
CONTINENT | | |
OF EUROPE | INDIA. | N. AMERICA. | S. AMERICA.
AND ASIA | | |
| | East of the West of the |
| | Rocky Mts. Rocky Mts. |
| | |
| |The Claiborne beds are considered |
| |by Lyell as the equivalent of the |
| |Middle Eocene of Britain; the |
| |parallelism of the other American |
| |deposits has not yet been |
| |completed. |
| | Uinta group |
| | _Uintatherium_ |
| | |
| | |
| | Bridger group |
| | Vicksburg |
| | beds |Deposits
| |T _Orohippus_ |believed
| |h M _Dinoceras_ |to be of
| |e a d _Uintatherium_|Tertiary
| | r e _Tinocoras_ |age, in
| |A i p Claiborne _Tillotherium_ |the Pampas,
Nummulitic |Nummulitic|l n o beds |contain
Limestone |formation |a e s |Palæotherium
of the | of Cutch,|b i |and
Alps, | portions |a t Green River |Anoplotherium,
Carpathians| of the |m s _Zeuglodon group |and other
N. Africa | Himalaya,|a cetoides_ |forms
Asia Minor| and | |presenting a
Western | frontiers|p |resemblance to
Thibet. | of China.|e |the fauna of
| |r |that period in
| |i |Europe.
| |o |
| |d |
| | |
| | |
| | |
| | |
| | Wahsatch |
| | |
| | |
| | |
| | _Coryphodon_ |
| | _Eohippus_ |
| | |
| | |
| | |
| | |
| | |
| | |
| | |
| | Laramic or Lignitic Period.|
------------------------------------------------------------------------
We learn, both from the nature of these deposits and from their organic
contents, that climatic oscillations have been passing during the whole
period of their deposition over the surface of the globe, and inducing
corresponding fluctuations in the character of the vegetable and animal
life abounding on it. A complete collation of these varying conditions at
synchronous periods remains to be achieved, but the study of our own
country, and those adjacent to it, shows that alternations of tropical,
boreal, and temperate climate have occurred in it; a remarkable series of
conditions which has only lately been thoroughly and satisfactorily
accounted for.
Thus, during a portion of the Eocene period a tropical climate prevailed,
as is evidenced by deposits containing remains of palms of an equatorial
type, crocodiles, turtles, tropical shells, and other remains attesting
the existence of a high temperature. The converse is proved of the
Pleistocene by the existence of a boreal fauna, and the widespread
evidences of glacial action. The gradations of climate during the Miocene
and Pliocene, and the amelioration subsequent to the glacial period, have
resulted in the gradual development or appearance of specific life as it
exists at present.
Corresponding indications of secular variability of climate are derived
from all quarters: during the Miocene age, Greenland (in N. Lat. 70°)
developed an abundance of trees, such as the yew, the Redwood, a Sequoia
allied to the Californian species, beeches, planes, willows, oaks,
poplars, and walnuts, as well as a Magnolia and a Zamia. In Spitzbergen
(N. Lat. 78° 56') flourished yews, hazels, poplars, alders, beeches, and
limes. At the present day, a dwarf willow and a few herbaceous plants form
the only vegetation, and the ground is covered with almost perpetual ice
and snow.
Many similar fluctuations of climate have been traced right back through
the geological record; but this fact, though interesting in relation to
the general solution of the causes, has little bearing on the present
purpose.
Sir Charles Lyell conceived that all cosmical changes of climate in the
past might be accounted for by the varying preponderance of land in the
vicinity of the equator or near the poles, supplemented, of course, in a
subordinate degree by alteration of level and the influence of ocean
currents. When, for example, at any geological period the excess of land
was equatorial, the ascent and passage northwards of currents of heated
air would, according to his view, render the poles habitable; while, _per
contrâ_, the excessive massing of land around the pole, and absence of it
from the equator, would cause an arctic climate to spread far over the now
temperate latitudes.
The correctness of these inferences has been objected to by Mr. James
Geikie and Dr. Croll, who doubt whether the northward currents of air
would act as successful carriers of heat to the polar regions, or whether
they would not rather dissipate it into space upon the road. On the other
hand, Mr. Geikie, though admitting that the temperature of a large
_unbroken_ arctic continent would be low, suggests that, as the winds
would be stripped of all moisture on its fringes, the interior would
therefore be without accumulations of snow and ice; and in the more
probable event of its being deeply indented by fjords and bays, warm
sea-currents (the representatives of our present Gulf and Japan streams,
but possessing a higher temperature than either, from the greater extent
of equatorial sea-surface originating them, and exposed to the sun's
influence) would flow northward, and, ramifying, carry with them warm and
heated atmospheres far into its interior, though even these, he thinks,
would be insufficient in their effects under any circumstances to produce
the sub-tropical climates which are known to have existed in high
latitudes.
Mr. John Evans[75] has thrown out the idea that possibly a complete
translation of geographical position with respect to polar axes may have
been produced by a sliding of the whole surface crust of the globe about a
fluid nucleus. This, he considers, would be induced by disturbances of
equilibrium of the whole mass from geological causes. He further points
out that the difference between the polar and equatorial diameters of the
globe, which constitutes an important objection to his theory, is
materially reduced when we take into consideration the enormous depth of
the ocean over a large portion of the equator, and the great tracts of
land elevated considerably above the sea-level in higher latitudes. He
also speculates on the general average of the surface having in bygone
geological epochs approached much more nearly to that of a sphere than it
does at the present time.
Sir John Lubbock favoured the idea of a change in the position of the axis
of rotation, and this view has been supported by Sir H. James[76] and many
later geologists.[77] If I apprehend their arguments correctly, this
change could only have been produced by what may be termed geological
revolutions. These are great outbursts of volcanic matter, elevations,
subsidences, and the like. These having probably been almost continuous
throughout geological time, incessant changes, small or great, would be
demanded in the position of the axis, and the world must be considered as
a globe rolling over in space with every alteration of its centre of
gravity. The possibility of this view must be left for mathematicians and
astronomers to determine.
Sounder arguments sustain the theory propounded by Dr. Croll (though this,
again, is not universally accepted), that all these alterations of climate
can be accounted for by the effects of nutation, and the precession of the
equinoxes. From these changes, combined with the eccentricity of the
ecliptic from the first, it results that at intervals of ten thousand five
hundred years, the northern and southern hemispheres are alternately in
aphelion during the winter, and in perihelion during the summer months,
and _vice versâ_; or, in other words, that if at any given period the
inclination of the earth's axis produces winter in the northern
hemisphere, while the earth is at a maximum distance from that focus of
its orbit in which the sun is situated, then, after an interval of ten
thousand five hundred years, and as a result of the sum of the backward
motion of the equinoxes along the ecliptic, at the rate of 50' annually,
the converse will obtain, and it will be winter in the northern hemisphere
while the earth is at a minimum distance from the sun.
The amount of eccentricity of the ecliptic varies greatly during long
periods, and has been calculated for several million years back. Mr.
Croll[78] has demonstrated a theory explaining all great secular
variations of climate as indirectly the result of this, through the action
of sundry physical agencies, such as the accumulation of snow and ice, and
especially the deflection of ocean currents. From a consideration of the
tables which he has computed of the eccentricity and longitude of the
earth's orbit, he refers the glacial epoch to a period commencing about
two hundred and forty thousand years back, and extending down to about
eighty thousand years ago, and he describes it as "consisting of a long
succession of cold and warm periods; the warm periods of the one
hemisphere corresponding in time with the cold periods of the other, and
_vice versâ_."
Having thus spoken of the processes adopted for estimating the duration of
geological ages, and the results which have been arrived at, with great
probability of accuracy, in regard to some of the more recent, it now
only remains to briefly state the facts from which the existence of man,
during these latter periods, has been demonstrated. The literature of this
subject already extends to volumes, and it is therefore obviously
impossible, in the course of the few pages which the limits of this work
admit, to give anything but the shortest abstract, or to assign the credit
relatively due to the numerous progressive workers in this rich field of
research. I therefore content myself with taking as my text-book Mr. James
Geikie's _Prehistoric Europe_, the latest and most exhaustive work upon
the subject, and summarizing from it the statements essential to my
purpose.
From it we learn that, long prior to the ages when men were acquainted
with the uses of bronze and iron, there existed nations or tribes,
ignorant of the means by which these metals are utilized, whose weapons
and implements were formed of stone, horn, bone, and wood.
These, again, may be divided into an earlier and a later race, strongly
characterized by the marked differences in the nature of the stone
implements which they respectively manufactured, both in respect to the
material employed and the amount of finish bestowed upon it. To the two
periods in which these people lived the terms Palæolithic and Neolithic
have been respectively applied, and a vast era is supposed to have
intervened between the retiring from Europe of the one and the appearance
there of the other.
Palæolithic man was contemporaneous with the mammoth (_Elephas
primigenius_), the woolly rhinoceros (_Rhinoceros primigenius_), the
_Hippopotamus major_, and a variety of other species, now quite extinct,
as well as with many which, though still existing in other regions, are no
longer found in Europe; whereas the animals contemporaneous with Neolithic
man were essentially the same as those still occupying it.
[Illustration: FIG. 19.--ENGRAVING BY PALÆOLITHIC MAN ON REINDEER
ANTLER.[79]
(The two sides of the same piece of antler are here represented.)]
The stone implements of Palæolithic man had but little variety of form,
were very rudely fashioned, being merely chipped into shape, and never
ground or polished; they were worked nearly entirely out of flint and
chert. Those of Neolithic man were made of many varieties of hard stone,
often beautifully finished, frequently ground to a sharp point or edge,
and polished all over.
Palæolithic men were unacquainted with pottery and the art of weaving, and
apparently had no domesticated animals or system of cultivation; but the
Neolithic lake dwellers of Switzerland had looms, pottery, cereals, and
domesticated animals, such as swine, sheep, horses, dogs, &c.
Implements of horn, bone, and wood were in common use among both races,
but those of the older are frequently distinguished by their being
sculptured with great ability or ornamented with life-like engravings of
the various animals living at the period; whereas there appears to have
been a marked absence of any similar artistic ability on the part of
Neolithic man.
[Illustration: FIG. 20.--REINDEER ENGRAVED ON ANTLER BY PALÆOLITHIC MAN.
(_After Geikie._)]
Again, it is noticeable that, while the passage from the Neolithic age
into the succeeding bronze age was gradual, and, indeed, that the use of
stone implements and, in some parts, weapons, was contemporaneous with
that of bronze in other places, no evidence exists of a transition from
Palæolithic into Neolithic times. On the contrary, the examination of bone
deposits, such as those of Kent's Cave and Victoria Cave in England, and
numerous others in Belgium and France, attest "beyond doubt that a
considerable period must have supervened after the departure of
Palæolithic man and before the arrival of his Neolithic successor." The
discovery of remains of Palæolithic man and animals in river deposits in
England and on the Continent, often at considerable elevations[80] above
the existing valley bottoms, and in Löss, and the identification of the
Pleistocene or Quaternary period with Preglacial and Glacial times, offer
a means of estimating what that lapse of time must have been.[81]
Skeletons or portions of the skeletons of human beings, of admitted
Palæolithic age, have been found in caverns in the vicinity of Liege in
Belgium, by Schmerling, and probably the same date may be assigned those
from the Neanderthal Cave near Düsseldorf. A complete skeleton, of tall
stature, of probable but not unquestioned Palæolithic age, has also been
discovered in the Cave of Mentone on the Riviera.
These positive remains yield us further inferences than can be drawn from
the mere discovery of implements or fragmentary bones associated with
remains of extinct animals.
The Mentone man, according to M. Rivière, had a rather long but large
head, a high and well-made forehead, and the very large facial angle of
85°. In the Liege man the cranium was high and short, and of good
Caucasian type; "a fair average human skull," according to Huxley.
Other remains, such as the jaw-bone from the cave of the Naulette in
Belgium, and the Neanderthal skeleton, show marks of inferiority; but even
in the latter, which was the lowest in grade, the cranial capacity is
seventy-five cubic inches or "nearly on a level with the mean between the
two human extremes."
We may, therefore, sum up by saying that evidences have been accumulated
of the existence of man, and intelligent man, from a period which even the
most conservative among geologists are unable to place at less than thirty
thousand years; while most of them are convinced both of his existence
from at least later Pliocene times, and of the long duration of ages which
has necessarily elapsed since his appearance--a duration to be numbered,
not by tens, but by hundreds of thousands of years.
[Illustration: FIG. 21.--ENGRAVING BY PALÆOLITHIC MAN ON REINDEER
ANTLER.]