The Philosophy of Animal Colours, Andrew Wilson

Episode Transcript

Speaker 1 (00:00):
The Philosophy of Animal Colors by doctor Andrew Wilson, originally
published in Knowledge, an illustrated magazine of Science, Plainly worded
exactly described, eighteen eighty one, Part one. There is a
suggestive passage in Butler's Hootebras which maintains that fools are
known by looking wise, as men find woodcocks by their eyes.

(00:24):
And if the axiom be correct, that a poet is
only great when he is true to nature, it must
be admitted that Butler has been singularly felicitous in this metaphor.
Whoever has seen a woodcock in its ordinary summer plumage
may form a good idea of the truth of the
poetic remark, as that bird moves about amongst the fallen
leaves of autumn, the grays and browns and yellows of

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its feathers mingle so beautifully with the like tints of
its surroundings, that the animal is absolutely concealed from any
view but the practiced eye of the sportsman, As has
been remarked of the bird in question, even the a
very conspicuous and ornamental tail becomes hidden from view in
a most singular fashion. Below these tail feathers exhibit a

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white color, tinted with a silver sheen, and marked with
a deep black. Nothing more conspicuous than such an ornament
can well be imagined. Yet the tail and its belongings
are nevertheless wonderfully concealed, for as the bird reposes, these
underlines and tints are placed downwards and above the ash
and gray tins mingle perfectly with the bird's surroundings. As

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the woodcock therefore rests amid its background of wood and
its foreground of fallen leaves, every line of its plumage
is made to assimilate so closely with the objects around
that the bird's presence, even a short distance off, is
not suspected. The woodcock is by no means alone in
this harmony betwixt its plumage and its surroundings. The sand

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grouse of the deserts, for instance, exhibit a like harmony.
These birds cannot be detected even as they run amidst
the sand of their haunts. So closely imitated in the
dull tints of their plumage is the tone of the
desert wild. The well known case of the ptarmigan is
even more extraordinary. Still in summer, the bird shows a
plumage of pearly gray, which conceals it perfectly as it

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lies on its bed of Scottish heather, mingled with the
lichen and its kith and kin. But when the winter
snows descend and coat the hillsides with a mantle of white,
then a kindly nature still contrives concealment for the ptarmigan.
In a fresh suit of color. The pearly grays of
the summer are replaced by a plumage of snowy whiteness,

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and save for its dark eye, there is little risk
of the discovery of the bird by the unwary or
unpracticed sportsman. The grouse and common partridge are not less
perfectly protected. The hues of the grouse match the tints
of the heather, and the partridge is almost as difficult
to discover, say, in a plowed field, as the ptarmigan
on the hillside. The birds just mentioned are all rasorial birds.

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That is, they are allied to the type of the
common fowl, and are typically ground livers. Their tints therefore
assimilate with those of the ground and with ground vegetation.
And whatever may be the ultimate philosophy which shows the
origin of such harmonies. It is very plain that the
utilitarian is bound to read protection in every line of
the story. Escape from their enemies must be favored by

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the correspondence and color to which we allude. The harmonies
of color present the safest and therefore the best foil
to the keenness of sight of the eagle, and to
the agility of the falcon and its kind. It is different, indeed,
with the songsters of the wood and grove, with well
developed powers of flight, and with a close refuge amid

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the foliage of the wood. The appearance of bright hues
and tints in these birds is by no means disadvantageous.
Another law, that of the development of color in relation
to sex, has taken precedence of the regulation of color
as a means of protection. If concealment be necessary, Nature
will teach the art of hiding in other ways than that,

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whereby she contrives to make the partridge face danger with
a stillness that almost rivals that of the stones, trustful
in the harmony of her plumage that so closely matches
her heather bed. But there are wider fields open to
the natural survey of color and its meanings. Suppose that
we peer for a moment into the class of fishes.

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We shall find the adaptation of color to surroundings illustrated
in a very apt degree. Whoever has tried to spear
a soul or flounder, for example, well knows that the
excitement of the sport consists in the endeavor to follow
out the axiom of Missus Glass, and on the principle
which that worthy lady laid down about first catching your hair,

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to first catch your flounder, you cautiously and slowly paddle
out to shallow water in your punt, and you drift
over the flat sandy beach at a depth of from
two to three feet below. The water is as clear
as crystal. Here and there you see a la lazy
starfish on the march, exerting himself to the utmost as
he slowly extends ray after ray, and crawls at the

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rate of about a mile a month or so by
aid of his hundreds of sucker feet. The sand eels
annoy you as they burrow downwards and send up little
clouds of dust on your approach. But the flounders you
came to spear, where are they? An echo? Seems? But
to answer where, But the practiced sportsman bid you learn,
as in all other sciences and arts, the first lesson, namely,

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how to see and observe. As your boat creeps along.
He points to what seems a mere sandy lump, but
in which his keener eye has detected the merest wriggle
of a fin. Dash goes the spear, and up comes
a flounder. And as you watch the ground, you see
dozens it may be of similar sandy patches swimming off
in rapid alarm. The flounder's back it is really the

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side of the fish on which it lies is white enough,
as we know, But the other side is as close
a representation of a sandy patch as you can see,
or as you can imagine. Small wonder then, that in
flounder spearing you experience the difficulties which nature throws in
the way of capture through likeness and color to the

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animal surroundings. It is the same with soul turbot, and
with the skates and angelfishes. Watch the first flounder you
see resting on the sandy bed of the aquarium tank,
and you will receive ample proof of the truth of
the foregoing remarks. And should you chance to see the
lazy monk or angelfish as it lies, prone, heavy, and

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indolent in the highest degree in the flow of its tank,
you may again understand something of the value of color
as a means of protection to animal life. In the
case of those queer fishes, the little sea horses or hippocampi,
with heads like horses, and with a body which at
large reminds one most forcibly of some figure from the

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Herald's college on a crest conceal a man is affected
in a slightly different fashion from that prevalent among the souls. Here.
The body, as a rule possesses long streamers or fringes
that mimic the seaweeds, so that as the animal reposes,
its body may well enough represent a stone to which
are attached fragments of marine vegetation. The Australian sea horses,

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which live among red seaweeds, have streamers of that hue
attached to their bodies, and the mimicry and imitation of
their surroundings are thus very complete even their near neighbors.
The pipe fishes with green bodies, when they fasten themselves
to some fixed object and lull in the water may
closely resemble an inert piece of green weed. Amongst even

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the highest animals, protective coloring is common. A lion's hue
matches the sand, as of tiger's stripes, according to mister Wallace,
imitate very closely the foliage and trees amidst which it crouches.
The camel's coat is sandy like its desert, and the
rabbits offer as plain examples as any of the color

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harmony in question. The polar bear is white like the
Arctic fox in winter dress, and the nocturnal rats and
moles are dressed in shades the opposite of the ghost
like hues that become so conspicuous at night. Part two.
But descending to still lower grades of life, we may
discover examples of this mimicry not only of surroundings, but

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also of lifeless or inorganic objects, and of it may
be plant structures as well. On the part of animals,
the so called stick insects, or walking twigs as they
are often called, the phasmody of the naturalist present us
with the most perfect reproductions of bits of dried twigs.
A figure of one of these insects is before me

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as I write it is represented climbing on the delicate
branch of a shrub, and but for the expectation of
what one is looking for, there would be considerable difficulty
in determining which is insect and which plant. The bodies
of these twig insects, which belong, by the way to
the Orthoptera, are that order which harbours the familiar crickets

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and grasshoppers, are represented by mere lines. The wings have disappeared,
and it has been remarked that in their gait these
insects exhibit a peculiar habit of using their legs in
a singularly awkward fashion, and thus apparently aid the illusion
of the spectator that he is regarding a dried twig
moved erratically by the wind. More extraordinary still are the

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leaf insects near allies indeed, of the walking sticks. Here
mimicry of the plant proceeds so far as to fully
justify the eminent naturalist remarks that it is strange to
find the animal assuming a mimetic disguise and aping the
actor's art. The wing in the leaf insects exactly imitate leaves.
The venation or arrangement of the veins in the leaf

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is clearly seen, and in one form phylium, even the
chest and legs of the animal assume leaflike characters when
such an insect rests amid foliage. The value of such
a close resemblance to its plant surroundings as a means
of protection can be readily understood. In some leaf insects,
all of which are tropical species, the wings resemble leaves

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that are dried and withered. In others, the minute fungi
that attack leaves are imitated. Mister A. R. Wallace tells
us that one of the walking sticks obtained by him
in Borneo was covered over with fullyaceous excrescences of a
clear olive green color, so as exactly to resemble a
stick grown over by a creeping moss or Juggermannia. The

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Daak who brought it me assured me it was grown
over with moss, though alive, and it was only after
a most minute examination that I could convince myself it
was not so. Lastly, there may be noticed, in connection
with these curious traits of animal life, the fact that
certain animals themselves harmless and inoffensive may assume the exact

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appearance of offensive neighbours. In this respect, certain butterflies are
facillo proncip. Certain South American butterflies, known collectively under their
family name of Heliconidae, exhibit a brilliant colouration, but likewise
possess a very strong odour, and it may be presumed
from the sequel, a highly disagreeable taste as well. They

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are highly conspicuous insects, and the undersides of their wings
are as brilliantly colored as the upper surfaces, so that
even in repose and when resting with the wings opposed
over the back, they are readily enough seen. Their colours
are prominent, not to say, gaudy yellows, reds, and whites,
commingle with blacks, blues and other tints in a striking fashion.

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They are, further, by no means rapid flyers, and putting
the foregoing circumstances of their gaudy colour and their slow
movements together, no group of animals would seem more liable
to the attacks of bird enemies than these helicon butterflies.
Yet the reverse is the case. So far from being decimated,
their race flourishes apace, and this result is clearly due

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to the strong odour and nauseous taste they possess. The
mere touch of a helicon is in itself a pungent matter,
which reminds one of nothing so much as the persistence
of the muskrats secretion, or the still more awful effluvium
of the American skunk. Their neighbor. Butterflies may fall victims
by the score to the rapacity of their feathered enemies,

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but the helicons are spared from even the semblance of attack.
So far, there seems nothing unusual or striking in a
group of butterflies being protected through strong odour and worse
taste from their natural enemies, the birds. But now comes
the most curious phase of this history. Another and distinct
family of butterflies, known as the Leptilidae, allied to the

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common white cabbage butterfly and removed from the helicons, also
possesses representatives in South America. There are no points of
agreement between the leptilely days and the helicons, save indeed
that both are butterflies. Furthermore, the leptili days are entirely
destitute of the nauseut odour and of the strong taste

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of the helicons. And in respect of their more agreeable presence,
should become a prominent article, as do other butterflies in
the bill of fare of the birds. Yet, strangely enough,
the leptilely days escape persecution, and their reason is not
far to seek or difficult to find. When they are
carefully examined, certain species of the leptili days are seen

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to be exact facsimiles in color and appearance of the
stinking helicons. Naturalists at first class both as helicons, until
a closer examination showed the difference between these butterflies, and
likewise proved that the leptili days had thus mimicked in
the plainest possible manner the colors of their strong smelling neighbors,

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nor other colors alone imitated. The very shape of the
helicon's wings is reproduced in those of the Liptilidas, and
the feelers likewise mimic those of the former group. Again,
special forms of liptili dase mimic special forms of helicons.
The flight has become of similar character in both species,

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and the habits have also been slavishly copied. Such instances
as these certainly represent food for thought to the reflective mind.
It is the business of philosophy to account for facts
by placing the facts in scientific juxtaposition. Philosophy, in this
light is the thread upon which the pearls of knowledge
are strung. What, then, it may be asked, is the

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philosophy which can explain the curious resemblances seen in the
animal world, ranging from say, a mere likeness intent to
the surroundings as in the flounder or woodcock, through more
intensified likenesses to the exact mimicry, and to the slavish
copy of color and form as in the butterflies. A

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first and highly important feature in the consideration of the
case is found in the fact that there is a
gradation in the degree of mimicry from the mere sand
or ground tinting of the flounder to the exact coloring
of the butterflies. Is of course a wide step, but
it is one which is bridged over by intermediate examples
and stages. Then, secondly, we discover a purpose or use

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in the disguises. That purpose, apart from any considerations of
its origin, being the protection of the animal from its
enemies and the consequent good and increase of its race. Thirdly,
it appears possible to account for these curious transformations and
disguises by finding an initial step. It is the old
story of the premier pa Qui Coute applied to natural

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history research. And this first step is found in the
solid axiom that every living species is liable to variation
and change. Next succeeds the consideration that such which varieties
as are produced have to struggle for existence. Suppose a
number of white varieties produced in a cold, snowy region,

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along with varieties of more conspicuous colors. It is evident
that whilst the white varieties will escape from their enemies,
the darker colored individuals would succumb. Thus, the white race
comes to the front and holds its own, and its
perpetuation and increase becomes a matter of surety. Summing up
the argument, we find that two factors are at work

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and bringing about these wonderful colour likenesses in the animal world.
The one is variation, producing the color varieties. The other
is the circumstances of life, which weed out the weak
and give the battle to the strong, which latter are
those whose colors best suit their surroundings. This is the
philosophy which natural history today lays down for our acceptance.

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Nay more, it is a philosophy which explains far more
important facts of life than mere mimicry. It is evolution
and development reduced to their plainest and fundamental terms. In
a word, Darwinism in a nutshell, as illustrated by the
variation and change that all life knows, and by the
warring of that life bringing the best of its units

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to the front of the battle. End of the Philosophy
of Animal Colors by doctor Andrew Wilson,