DARWIN AND WALLACE
We have seen in the last chapter that whenever men have actively
thought they have attempted to explain the origin of plants and
animals as well as of themselves. No one who wrote previous to the
time of Charles Darwin had expressed any idea concerning this matter
with force enough to convince any large portion of the thinking world.
If Lamarck had fallen on better times, if the great Cuvier had not
laughed him to scorn, if Goethe had found him out and made him known
to the world, evolution might have come into its own sooner. None of
these conditions arose, and it remained for Charles Darwin to give to
the world in clear and cogent form the thought of evolution. He
gathered so much material before he expressed his opinions, and looked
at the matter from so many sides that, when he published his results,
he had foreseen most of the objections which were subsequently to
arise in opposition to his announcement. Charles Darwin is recognized
to-day as the father of the evolutionary movement.
It has been sometimes said in recent years that Darwinism is dead, and
there is a sense in which this is true. Unmodified and unassisted
natural selection is not to-day considered by most scientists a
sufficient agent for producing evolution. But everyone connected with
the subject acknowledges Darwin as the master, and says that it was
his work which converted the world to a belief in evolution. We can
have no better preparation for an intelligent understanding of this
subject than to consider carefully the life of this remarkable man and
the circumstances under which he came to his epoch-making conclusions.
Evolution has taught us to attempt as far as may be to account for man
on the basis of his heredity or of his environment. It is interesting
to note that both of these factors in Darwin's case were entirely
favorable. In the latter part of the eighteenth century Erasmus Darwin
had given to the world an astonishing poem in which he anticipated not
a little of the thought which his more famous grandson was to make so
widely known. Josiah Wedgwood had learned to make for England her most
famous pottery, no quality of which was more widely recognized than
the sterling patience with which it was made. Erasmus Darwin, with his
scientific proclivities, and Josiah Wedgwood, with his sturdy common
sense and patient workmanship, united to give Charles Darwin his
inherited tastes, for he was a grandson of both. Born in 1809, on the
banks of the Severn in England, Charles Darwin was the delicate son of
a practicing physician of modest but sufficient means. Owing to his
lack of early vigor, Darwin spent much time in the open air, and in
his excursions about his home was chiefly interested in collecting
beetles. This taste, which lasted through all his young manhood, is
the one early indication of the traits that were later to develop. At
first in the day-school and later in the preparatory school Charles
Darwin was anything but a satisfactory student. Even a kindly desire
later to make the most of him makes it impossible to find traces of
any especial fondness for earnest study. He himself believed his
education to have been nearly useless, although he doubtless
under-estimated its value. At the age of sixteen he went to Edinburgh
at his father's desire, to study medicine. The sight of the
dissecting-room nauseated him completely, and he refused to continue
working in it. Later an operation which he witnessed in a clinic at
the hospital sickened him so thoroughly that he declined to attend
further operations. It became evident that the young man was not
adapted to the life of a physician. The next move was to educate him
for the church, and for this purpose, at the age of nineteen, he went
to Cambridge. Here it soon appeared that he was no better adapted to
the ministry than he was to the practice of medicine, and his
university career went on in very desultory fashion. Most of his work
was distinctly neglected, but two of the men he met there were to
influence largely his future life. Henslow, the botanist, was
unusually fond, for a professor in those days, of work in the field.
Charles Darwin's tastes coincided with those of Henslow, with whom he
formed an intimate friendship. He was always welcomed as a companion
on the field trips. Though he studied little of botany in the
classroom or laboratory, he was constantly with Henslow or with
Sedgwick in the field. Sedgwick was the professor of geology, and of
him Darwin was particularly fond, and under him did much the largest
amount of his study. When he came up for graduation he ranked tenth of
those who "did not go in for honors," a not very remarkable class
standing. He was still required to put in two years of residence, and
during this interval he spent most of his time with Sedgwick in the
study of geology in the field. Returning to his home after a
geological trip into Wales, Darwin found awaiting him a letter from
Henslow, offering him an appointment that opened to his ardent mind
the door to a career after his own heart.
The British nation, being the greatest commercial nation of the globe,
has the greatest need for accurate charts of all the seas. Frequently
she has sent out great charting expeditions to various parts of the
world. One of these was to go out in Her Majesty's ship, _Beagle_, for
a voyage around the world. Captain Fitzroy was in command, and he was
especially commissioned to map the coast of South America from La
Plata to Cape Horn and up the western side. In addition to this work,
by carrying a set of accurate chronometers, he was to check up the
longitude of the various ports to be visited in this circumnavigation
of the globe. It was customary on such expeditions to carry a young
man whose duty it was to study the natural history of the countries
visited on the trip. The salary of such a naturalist was so small that
an experienced man could scarcely afford to take the place. Therefore
the appointment usually went to a man rather of promise than of
achievement. Through Henslow's influence, Charles Darwin was offered
this position in 1831. Darwin hastened to obtain his father's
permission, but the elder Darwin at first declined to consider the
matter. He felt that his son had not made such use of his time at the
university as warranted the hope that much could be expected of such a
journey. He believed it necessary that Charles should have some means
of earning an adequate living before he could think of devoting his
time to science. Charles found an efficient advocate in the person of
his uncle, Josiah Wedgwood, Jr. Together they persuaded the father of
the propriety of giving to Charles this opportunity to follow out his
real tastes and ambitions. Accordingly, at the age of twenty-two, we
find him embarked on a journey around the world. In the cabin of the
_Beagle_ he had abundant time, in his long sail across the Atlantic,
to read the two volumes of Lyell's "Elements of Geology," which
Henslow had handed him, with the suggestion that he read it, but on no
account believe it. Filled with the love of geology as Darwin was,
this epoch-making book was exactly the stimulus needed. Lyell had just
begun to persuade the world that to understand the past we must study
the present. In the forces now at work he saw cause enough to account
for all the history of the past of the earth.
There is little doubt that this book was one of the most potent
factors in determining the bent of Darwin's mind. His entire
educational experience had failed to appeal to him. It is fortunate,
we now know, that this was the case. If the university course of the
time had really seized him it would have made but one more student
like hundreds it was turning out each year. For most of us this is the
happy event. Now and then comes the rare spirit to whom all of this
fails to appeal because he is ready for something better. Such was the
spirit of Charles Darwin. He started on his journey with a mind
singularly free from prepossessions. In the long hours of this sailing
voyage across the Atlantic Ocean Darwin had time to read and ponder
Lyell's weighty words. By the time he reached the Brazilian shore he
was filled with Lyell's conception that the present is the child of
the past, developing out of it in orderly sequence. Lyell expressly
denied that this is true of the animal and plant world. He applied it
only to the face of the earth, with its mountains of uplift and its
valleys of erosion. But the underlying principle of an orderly
development under the action of natural causes was there. In Darwin's
mind this at once found acceptance, and was destined to a fruition its
author had expressly disclaimed.
The narrative of this voyage, as subsequently written, describes the
islands visited by the _Beagle_ in crossing the Atlantic Ocean. The
contrast between the simple and general interest in these islands and
the care with which Darwin described the Galapagos and the Keeling
Atoll visited later in the voyage are speaking evidence of the rapid
development going on in the mind of the young naturalist.
Reaching the shore of South America, Darwin first turns to its
geology. But before long the animal life attracts his attention. In
the Brazilian forest Darwin had his first experience of the wealth of
animal and plant life in the tropics, and, like all naturalists, he
was very enthusiastic over it. Among the animals that particularly
attracted his attention was the sloth, a peculiar creature climbing
slowly about the trees, small of size and sluggish of habit. Another
animal that interested him greatly was the little armadillo with its
interesting habit of curling up in its plated skin.
Captain Fitzroy soon finished what work he was required to do in this
neighborhood, and Darwin was called back to the _Beagle_ to continue
his voyage. When they arrived at the mouth of La Plata their most
serious work began. Here there was much tedious charting for Fitzroy,
and Darwin could now leave the vessel for a lengthy trip on shore.
This was doubly welcome. Seasickness was nearly constant with Darwin
while on this entire voyage and every opportunity to work on land was
eagerly seized. This region, too, was rich in objects of interest and
in strange people. While exploring the pampas, beyond Buenos Ayres,
Darwin came across the skeletons of the great mammals some of which
Cuvier had previously described. He studied these bones with much
care, and recognized at once in the megatherium a great similarity in
structure to the sloth he had seen in Brazil. The enormous skeletons
of the glyptodons struck him also as strangely similar to that of the
armadillo. One evening, seated alone in the broad expanse of the
pampas, the idea suddenly swept over him, stimulated, of course, by
his study of Lyell: "Can it be that the little armadillo and the sloth
of to-day are the degenerate descendants of the enormous megatherium
and glyptodon of the past?" But his mind was not yet ready to accept
so bold an idea and he swept it aside.
The people of this wild neighborhood interested Darwin very greatly,
and he describes them with care. In this connection a charming trait
of Darwin's character comes beautifully in evidence. The absolute
purity of his mind, his utter freedom from grossness, shows clearly in
his account of the first really semi-civilized people he had ever
seen.
A little later, while exploring Patagonia, Darwin noticed the
terrace-like formation of that desolate country. A flat near the sea
was succeeded by a rapid rise, then came another flat. Three of these
terraces in succession stretch back toward the Andes. At the base of
the high terraces Darwin found marine shells, largely similar to those
of the ocean beach so many miles to the east. His study of Lyell led
him to suspect at once that this portion of South America had been
raised in successive stages out of the bed of the Pacific. When they
passed around Cape Horn and up the western coast he hunted for
similar beach marks on the sheer western face of the Andes, and found
them without difficulty, confirming his idea of the recent rise of
this end of the Andean chain.
The _Beagle_ continued its voyage up the western coast of South
America until it reached Peru. Once more the abundance of tropical
life is under Darwin's eyes, but now it is the life of an entirely
different section. The dry climate of Peru furnished him with an
environment distinctly unlike that of the moist Brazilian forest. He
collects now with avidity, gathering especially insects and birds.
Then the ship turned its prow westward across the Pacific, only to
stop five hundred miles out at the Galapagos Islands. This little
group he studied intensely, collecting large numbers of insects and
birds. He had not worked over his collection long before he realized
that each island in the group had peculiarities which marked its
animals from those of any other island. Whenever two islands were
close together in the group the differences in their fauna were found
to be comparatively slight. If, however, he examined the animals from
two islands lying at opposite ends of the group, the differences were
always considerably greater. There was, however, a strong general
resemblance among them all and a distant though not so strong
resemblance to the corresponding animals of the Peruvian coast. On
leaving the Galapagos group, Charles Darwin writes in his diary the
suggestive observation that this little group of rocky islands seems
to be one of the greatest centers of creative activity. It was this
interesting resemblance of the animals of these islands to each other
and to those of the Peruvian coast that finally persuaded Darwin that
they were all related and were all descended from those of Peru. For
the rest of his life, with an intensity which increased with each
year, Darwin persisted in a patient search for the possible agencies
by which such change could have been brought about. The problem,
however, was temporarily eclipsed by a pressing geological question
aroused by his visit to the Keeling Atoll. Here his investigation of
coral reef formation absolutely captivated him. In the case of most
coral islands in the Pacific Ocean the reef exists as a circle of
coral enclosing a lagoon of water. In the center of this lagoon stands
commonly a rocky island. It is plain that this is the foundation on
which the coral built. But, in the case of the Atoll, the coral ring
was present and so was the internal lagoon, but there was no rocky
island. The key to the solution came with an interesting discovery.
Darwin began to put down a grappling iron on the outer side of the
reef and to drag up coral. The farther away from the reef he went the
deeper was the water from whose bottom he pulled the coral. What at
first puzzled him was the fact that so long as he dragged up his coral
from depths of a hundred feet or less the coral was alive. Whenever he
went to depths of much more than a hundred feet, his coral was always
dead, though he was evidently pulling it from situations in which it
had grown. Then Darwin remembered the rising Andes, lifting themselves
out of the bed of the Pacific. Here was the correlated movement. The
bottom of the ocean here was sinking. As it sank it dragged down the
corals with it. But the descent was so slow that new corals could
build on top of the others fast enough to keep the reef up to the
surface of the water. At the rate of growth of coral, this would seem
to mean that the bottom could be sinking at a rate of only a few feet
a century. But while the reef could keep up to the surface, the rocky
island must slowly sink. Darwin inferred that there must be a rocky
summit within the lagoon, below the surface of the water. A little
sounding soon discovered this island, and the verification of Darwin's
theory of coral reef formation was at hand. The description of this
Atoll and of his theory of its formation won for Darwin the esteem of
geologists when he later presented it in book form.
The voyage was continued around the Cape of Good Hope. Pursuing the
usual course of sailing vessels, the _Beagle_ touched once more at
Brazil, returning home to England in 1836, after an absence of five
years. Charles Darwin himself believed this trip to have been both his
education and his opportunity. He had started on it a rather careless
and indifferent student. He returned from it the most painstaking and
patient naturalist the world has ever known. His father, who had
hardly consented to his going because he believed him not stable
enough to be intrusted to his own devices for so long a period, was
profoundly moved at the sight of him on his return. Believing in
phrenology, as did many of the physicians of his time, his father
turned to his mother and said, "Look at the shape of his head; it is
quite altered"; which, translated into the language of to-day, would
read, "How wonderfully the young man has developed."
A part of Charles Darwin's duty to the British Government was to write
a narrative of the voyage, and this account of his trip upon the
_Beagle_ is one of the great classics of travel in the English
language. It won the confidence and respect of a wide circle of
readers. In his next book he published his observations made at the
Keeling Atoll and announced his theory of the formation of coral
islands. This was a distinctly scientific investigation, and it won
such immediate favor among geologists as to increase materially the
young man's reputation. No one man is ever widely enough acquainted
with the animal world to classify all the specimens gathered on such
an expedition. In accordance with custom, Darwin began distributing
his collections among specialists. Each of these was to identify and
describe, to name, if necessary, the kind of material he knew best.
Among others, Darwin had a considerable collection of barnacles
gathered from boats and wharves in all parts of the world. As he could
find no one sufficiently acquainted with these creatures to classify
them he decided reluctantly to work them up himself. For about eight
years much of his spare time was given to this painfully exacting
work. He expresses himself as fearing it was a waste of time. Few
systematic workers will agree with him. He did his work so well that
it has been unnecessary for anyone to do it again. In addition it
gained him the esteem of a new circle of scientists and that a
decidedly exclusive circle.
The publication of these books did much for Darwin. His narrative of
the voyage gained the good will of cultured England in general. The
book on coral reefs won the geologists. His "Manual of the
Cirrhipedia" (as the barnacle book was called) secured the attention
of systematic zooelogists. The time was not far distant when he would
need every aid possible toward gaining and keeping the regard of men;
for he was to promulgate a theory that would arouse the bitterest
opposition and the keenest scorn.
All the while Darwin was working on these books his mind was quietly
busying itself with what he called the species question. The more he
studied the material collected on his long tour, the more confident he
became that the animals of the present are the altered descendants of
the animals of the past. He tried patiently to work out every
conceivable hypothesis to see whether he could account for the
alteration. He felt quite sure animals changed, but how they changed,
and why, he could not for a long time conceive. He knew that gardeners
were constantly producing new varieties of plants, and that animals of
various breeds were clearly the descendants of other and familiar
varieties. Accordingly he began to study the methods of animal and
plant breeders, to visit their farms, to open correspondence with them
and read all their trade journals, to undertake experiments in the
breeding of plants. The longer he worked the more confident he became
of the reality of the change; but for a long time no glimmer of the
cause by which it could be brought about came to his mind. In 1838 he
came across a book by Malthus called "An Essay on Population," in
which the author shows that, whereas man increases by a geometric
ratio, he cannot hope to increase his food supply in more than an
arithmetic ratio. That is, while the food might increase like the
series 2-4-6-8-10, the population would increase like the series
2-4-8-16-32. On this basis it is only a question of time when the
earth will be too full of people for it to be possible for the food to
sustain them. Malthus added many observations and suggestions, but
this is as much of the book as interests us in this connection. Here
was the idea that suggested to Darwin his agency for producing the
change of the animals of the past into those of the present.
The number of animals of any particular species remains practically
the same. There may be a few more one year, and a few less another,
but on the average, year by year, the number of toads, the number of
blacksnakes, the number of field mice, remains sensibly the same.
Sometimes the rise of man brings an end to the wild population, and so
in the past animals have dropped out of the race. Yet in the long run
and for a considerable time the number of any species is constant. But
each animal produces offspring in quantities sufficient to far more
than replace himself as he dies out. In other words, animals increase
not by addition but by multiplication. Too many are born for all of
them to live. What becomes of the great mass of them? The answer is
they die; most of them die young. Only a few fortunate individuals,
favored by being a little stronger, a little more cunning, a little
more attractively colored than their mates, survive to carry on the
race.
The skillful gardener, looking over his flowers, finds a plant of more
than ordinary beauty and thrift of growth. When it comes to maturity
he keeps its seeds separate from those of the rest and next year
plants them by themselves. As they come up he weeds out all unthrifty
plants, only allowing the strongest to come to maturity. As they break
into bloom he plucks away all whose flowers do not come up to the high
standard he has set for himself. After a while he has but a few plants
left, but these are the thriftiest and bear the most beautiful
flowers. Again he allows these to mature and selects the seed of the
very finest. Next year the process is repeated. After a few
generations, usually three if the man is skillful enough, he has a
definite strain of flowers that will thereafter come true. This is the
process of artificial selection as carried on by man.
Darwin saw that Nature is constantly carrying on a similar process.
She produces seeds enough on almost any plant to clothe the world in a
few years if all of them could fall into proper ground and thrive like
their parents. A friend of mine found a mullein stalk that bore more
than seven hundred seed pods and averaged more than nine hundred seeds
to the pod, a total of more than six hundred and thirty thousand
seeds. If each of these could find lodgment on a plot eighteen inches
square, produce a similar number of seeds and plant them all, the
result would be overwhelming. The fourth generation would cover land
and sea, from pole to pole, one hundred layers deep. But there is no
such danger. Year by year the mulleins hold their own and no more. Any
particular field may have more or less, but in the long run the
average for a district is about the same. Some of the seeds are poor
and thin. These scarcely sprout. Others spring up into thin-skinned
plants, and the first frost nips them. Still others lack the woolly
coating in its finest abundance, and the browsing animals eat these.
Others lack power to put out a wide-ranging root supply and the first
drought kills these. Still others fail to send up a vigorous stem and
the passing animal knocks them over and they die. Of the few that are
still surviving, some produce such small and inconspicuous blossoms
that the insects scarcely see them, and they go unfertilized. In the
end only the aristocrats of the group are left, aristocrats in the
best sense of the word. These are strong, thrifty, and beautiful, and
are provided with every defense known to the mullein world. From these
the mulleins of the next generation will spring. Again Nature will
select the best of these, by a repetition of the same process. Thus
year by year the stock is improved. Any new feature that is favorable
helps its possessor to survive, and, if happily mated, will show
itself after a while in the entire group. This, in brief, is the
underlying idea of Natural Selection, as Darwin conceived it.
In 1842, at Lyell's suggestion, Darwin wrote a short sketch of his
ideas which he, two years later, expanded into a somewhat larger
account. The manuscript of these early views of the theory was
completely lost and has only been recovered within the last few years.
It was recently published under the editorship of Charles Darwin's
son, Francis. It is astonishing to see how clearly the first short
sketch states the underlying conception which all of Darwin's
subsequent work amplifies. Hooker was constantly urging Darwin to
write out his whole theory in the form of a book, and Darwin had begun
to do so in 1856.
Meanwhile, down in the Moluccas, Alfred Russell Wallace had been lying
sick of a fever contracted during his exploring expedition in that
neighborhood. He had been studying the distribution of the animal life
of the Malay Archipelago. Overcome by sickness, as he lay in bed, he
began to think over a book which he had read not long before, "Malthus
on Population." Wallace had been pondering on the question of the
origin of the animals of the Malay Archipelago. He had not the
faintest knowledge of what Darwin was doing, but was influenced, of
course, like Darwin, by what he read in Malthus. Interesting to
relate, he had come to exactly the same conclusions, writing his
opinions in the form of an essay. By the strangest sort of
coincidence, he sent this essay to Charles Darwin, asking him to read
it, and, if he thought it was not altogether too foolish, to send it
to Lyell for publication by the Linnaean Society. Darwin read with
utter astonishment this essay containing views so absolutely like
those that had come to him from his own long series of observations
and reflections. With uncommon magnanimity his first impulse was to
withhold his own publication entirely, but to this Lyell and Hooker
would not for a moment consent. They were determined that Darwin
should give them his long series of notebooks as evidence of the
independence of his work and that he present to the Linnaean Society,
simultaneously with Wallace's paper, one of his own upon the same
subject. In this manly form both essays were read at the next meeting
of the society. The joint papers provoked instant discussion and
prompt opposition. The world at large scarcely admitted a possible
doubt of the fixity of species. Men generally believed the idea to be
absolutely irreconcilable with their religious faith. Any question of
the fact that the species of to-day exist practically as they had been
handed down to the earth in the beginning by the Creator himself
seemed to most men a direct blow at religion. At this time a very
large number of natural scientists were clergymen, hence the
opposition had abundant and influential support. The storm grew
fiercer and more widespread. The publication in 1859 of Darwin's great
book on "The Origin of Species by Means of Natural Selection or the
Preservation of Favored Races in the Struggle for Life" added fuel to
the flame.
In 1860 the British Association met in Oxford, and Bishop Wilberforce,
the retiring president, in accordance with the custom of the society,
gave a summary of the advance of science, especially during the
preceding year. Everyone knew perfectly that the bishop would deal
with the species question, and that he would handle it severely.
Darwin was prevented by his usual ill health from being present at
this meeting, but Huxley was there to see that their side of the
question received proper attention. The bishop made a lengthy address,
in the major portion of which he brought forward entirely worthy
objections to Darwin's theories. Toward its close his feelings
overmastered him and he departed from his manuscript and unburdened
his mind. The lack of stenographers in those days and the tenseness
of the moment, which made everyone forget to take down what was said,
make it impossible to tell exactly what happened. It seems that Bishop
Wilberforce, appealing to the prejudices of his audience, said, in
language that now seems ludicrous but then was terribly bitter:
"However, any of us might be willing to consider ourselves descended
from an ape upon his father's side, no one would so demean his
mother's memory as to imagine that she could possibly have shared in
this descent." Huxley, who had waited patiently for the close of the
bishop's address, saw immediately the fatal mistake. Turning to his
companion beside him, he said, "The Lord has delivered the Philistine
into my hands," and, rising, he hurled back at the bishop the
indignant reply, "I should far rather owe my origin to an ape than I
would owe it to a man who would use great gifts to obscure the truth."
The bishop had made the mistake, and the struggle was on. Year by year
it raged. One by one the scientists, first of England, and then of
Germany, took their stand by Darwin. Huxley in England and Haeckel in
Germany were the foremost advocates of the Darwinian idea. Long and
fiercely the battle raged; slowly and gradually men began to see that,
instead of undermining religion, the idea of evolution uplifted
creation and made it not a strange happening in the distant past, but
a divine activity through all time. But the battle had by no means
subsided when one day came the sad news that Darwin's heart, so long
feeble, so serious a hindrance to his work, had beaten its last on
April 19, 1882.
His own people wished to bury Darwin quietly at his home in Down, but
Darwin now belonged to the nation. A petition signed by many public
men was sent to the Dean of Westminster, asking that his body might be
granted burial in the Abbey. Probably no greater honor can come to man
to-day, and fortunately Dean Bradbury was broad-minded enough to
acquiesce. So it came to pass that the church that had so long
believed him her enemy, that had first so bitterly fought him, came at
length to see that he added a new dignity and worth to her faith, and
took him to her bosom. Darwin's body lies buried in the Abbey.
In all the glorious company of immortal dead whose earthly frames are
gathered in England's great mausoleum, there is no other one who has
done so much to modify the mind of thinking man.