Beautiful spiders—The “Peckham paper”—Spider courtship—Male
antics and love-dances—Occasional accidents—Strength of the
evidence—The one explanation—Darwin’s last words—His theory
established.
SPIDERS, as we have seen, may attain beauty by getting more and more
like flowers, but beauty is not the attribute with which they are
principally connected in our minds. Rather they are a synonym of
something uncouth and horrid-looking, as well as of skill and
persevering industry. For those of us, however, who have lived in the
tropics they have other associations, for here, side by side with the
most hideous of monsters, huge, dark, and hairy, are found others, small
and gem-like, flashing indeed with beauty, the representatives in their
order of the humming-birds, those “living sunbeams” of the Indians,
amongst birds. These lovely little spiders belong to a particular
family, the _Attidæ_, which has been placed by common consent at the
head of all the others, since, whilst structurally, and in other
respects, it is inferior to none, “it contains among its 1,500 species
the greatest amount of sexual differentiation and the highest
development of ornamentation.” Dr. Wallace, after noticing “their
immense numbers, variety, and beauty,” in tropical South America, says,
“Many of them are so exquisitely coloured as to resemble jewels rather
than spiders”;[130] and again, in his work on the Malay Archipelago, he
alludes to them as “perfect gems of beauty.”[131]
These little radiant spiders live amongst flowers and foliage, and here
they chase such small insects as their size allows them to cope with.
Besides running, they make little leaps into the air, and so, if they
can manage it, come down on their prey, for which reason they are often
called “jumping spiders.” This is a very different mode of action from
that of remaining perfectly still till a butterfly or other insect
happens to settle on one, and it is accordingly instructive to find
that, great as is the beauty of these flower-haunting spiders, yet it
does not resemble that of the flowers amongst which it is displayed. The
iridescent flashes and sparkles more resemble those of the mineral than
of the vegetable world—where, indeed, they hardly exist—and must serve,
as well as their active movements, to point them out to their enemies
even amidst a background of flowers. It is not upon principles of
protection, therefore, or to acquire a dissembling resemblance that such
bright brilliancy has been developed in these little creatures.
Since, therefore, these spiders could not have become beautiful on any
principle of protective or aggressive resemblance, nor yet of warning
coloration, for which there would here be no opening, and had yet become
beautiful in a high degree, they seemed to Professor and Mrs. Peckham to
offer a good subject for the testing of the theory of sexual selection,
and deciding as to whether Darwin or Wallace was right in that matter.
After several months of careful, and often very laborious
observation—rewarded, however, by the most interesting results—they have
given their answer, and this answer, resting as it does on the most
irrefragable evidence, should be decisive for all time. It may safely be
asserted that anyone who, after reading the “Peckham paper,” as it may
well be called, is not convinced both that the male spiders of this
beautiful family woo the females by displaying their beauty before them,
and that the females carefully watch the display, accepting only such as
please them sufficiently and rejecting the others, never will be
convinced, since only by the spiders actually speaking, which is not
likely to happen, could the evidence be bettered. If, indeed, the female
had been heard to say “Pretty i’ faith,” or “You are a fine young man,”
just before her actions gave clear, or still clearer indication that
this was in her mind, had she murmured “Take me” as she let herself be
taken, and had the male asked, after the way common in novels, “Was it
my abdomen or the stripes on my palpi that made you first fall in love
with me?” then, perhaps, even those who believe that the higher
spiritual love is for man alone would have been converted—and yet I know
not, since assertions so unlikely in themselves might have flung doubt
on the whole paper.
But, however this may be, the evidence now offered us in favour of
Darwin’s views can never be strengthened except in this way, so that, as
far as proof is possible in such a matter, sexual selection as a law and
principal agent of beauty in nature is now proved, though, at the same
time, several more facts are added to those upon which the counter
hypothesis seems based, and which would certainly prove it in
Topsy-turvydom. To take these first, the authors of the paper in
question have sought to apply to spiders “the hypothesis that the
brighter colour of the male is due to his greater activity and vital
force.” “Beginning,” they say, “with the most brilliant family—the
_Attidæ_—we find that the females are, with few exceptions, larger,
stronger, and more pugnacious than the males. Thus we placed two females
of _Phidippus morsitans_ together in a glass jar. No sooner did they
observe each other than both prepared for battle. Eyeing each other with
a firm glance, they slowly advanced, and in a moment were locked in
deadly combat. Within a few seconds the cephalothorax of one was pierced
by the fang of the other, and with a convulsive tremor it relaxed its
hold and fell dead. We placed together eight pairs in all, and in each
instance the fight was short and even to the death. Subsequently we put
in a well-developed male, which, though smaller, was compactly built and
apparently strong enough to bring the virago to terms, but to our
surprise he seemed alarmed and retreated, trying to avoid her. She,
however, followed him up and finally killed him.”[132]
So much for _Phidippus morsitans_. Coming to _Dendryphantes elegans_,
the authors, who kept a number together in a large box, “were much
struck by the greater quarrelsomeness of the females. They would
frequently go out of their way to chase each other, and they were much
more circumspect in approaching each other than were the males.”[133]
Again they say, “Valkenaer, Menge, Hentz, and others give numerous
instances where the male meets his death through the fierceness of his
mate. In fact the danger is so imminent that after a successful
courtship it is the habit in several genera (e.g. _Epeira_ and
_Tegnaria_) for the male to retire with precipitation from the web of
the female as a reasonable precaution; yet the rule is for the male to
be more ‘beautified’ than the female.”[133]
Coming now to the actual courtship of these brilliant spiders, the
authors placed pairs of several species in square wooden boxes, having a
cloth bottom, on which they could easily move about. One of the species
experimented on was _Dendryphantes elegans_ mentioned only a moment
ago—such a name is not to be forgotten—whose beauty is thus described:
“The male is covered with iridescent scales, his general colour being
green. In the female the colouring is dark but iridescent, and in
certain lights has lovely rosy tints. In the sunlight both shine with
the metallic splendour of humming-birds. The male alone has a
superciliary fringe of hairs on either side of his head, his first legs
being also larger and more adorned than those of his mate.”[133]
Yet the extra vigour from which this special growth is supposed to have
sprung has not, as we shall see, affected his growth in general. “The
female is much larger, and her loveliness is accompanied by an extreme
irritability of temper, which the male seems to regard as a constant
menace to his safety; but his eagerness being great and his manner
devoted and tender, he gradually overcomes her opposition. Her change of
mood is only brought about after much patient courting on his
part”.[133] And now comes the minutely interesting description of this
iridescent, _couleur de rose_ courtship. “While from three to five
inches distant from her he begins to wave his plumy legs in a way that
reminds one of a windmill. She eyes him fiercely, and he keeps at the
proper distance for a long time. If he comes close she dashes at him and
he quickly retreats. Sometimes he becomes bolder, and when within an
inch pauses with the first legs outstretched before him, not raised, as
is common in other species; the palpi also (in insects it would be the
antennæ) are held stiffly out in front, with the points together. Again
she drives him off, and so the play continues. Now the male grows
excited, as he approaches her, and while still several inches away
whirls completely around and around; pausing, he runs closer, and begins
to make his abdomen quiver as he stands on tiptoe in front of her.
Prancing from side to side, he grows bolder and bolder, while she seems
less fierce, and yielding to the excitement, lifts up her magnificently
coloured abdomen, holding it at one time vertically and at another
sideways to him. She no longer rushes at him, but retreats a little as
he approaches. At last he comes close to her, lying flat, with his first
legs stretched out and quivering. With the tips of his front legs he
gently pats her; this seems to arouse the old demon of resistance, and
she drives him back. Again and again he pats her, with a caressing
movement, gradually creeping nearer and nearer, which she now permits
without resistance,”[133] and so on,
“Till the happy ‘yes’ falters from her mouth,”
almost as exciting, though not quite so detailed, as the climax scene of
a latter-day novel.
------------------------------------------------------------------------
[Illustration: 1. A solitary spider dancing before its mate.]
------------------------------------------------------------------------
[Illustration: 2. A cockroach attacking an astonished scorpion. Its
weapons are the spines on its powerful hind legs.]
Of the courtship of another species—_Habrocestum splendens_—we have the
following account: “The male, a magnificent fellow when we first caught
him, displayed for a long time before the female. He began by advancing
a few inches before her, and then backing off again, this being repeated
many times. After a while he settled down under a little web in the
corner. The female, troubled by this indifferent treatment, advanced
towards him; he came out and she fell back. This play was kept up for
some time, but at length the male began his courting in earnest. When
within a few inches of her he began a rapid dance from side to side,
raising the whole body high on the tips of the legs, the first pair
being directed forward and the palpi clasped together, with the abdomen
turned to one side and lifted up. After a short dance he stood
motionless, striking an attitude and remaining quiet for half a minute.
Then he turned his back on her, moving irregularly about, with his legs
forward and his palpi vibrating. Again he dances sideways before her,
strutting and showing off like a peacock, or whirling around and
around.”[133]
On such occasions the female would “commonly move nearer to him and
appear much excited herself. We at first supposed that this turning
around was accidental, but it happened so regularly at a certain stage
of the courtship that we concluded it was an important part of the
display, serving to better show off his brilliant abdomen.”[133] Of this
there can hardly be a doubt, since on every occasion the male spider,
whatever his species, assumed such attitudes as displayed his best
points to the best advantage—a fact which recalls the following passage
in one of Darwin’s letters: “I am very glad to hear of your cases of the
two sets of _Hesperiadæ_ (a butterfly), which display their wings
differently, according to which surface is coloured. I cannot believe
that such display is accidental or purposeless.”
How glad, and more than glad, would Darwin have been to have read the
tale of these spiders! It is, indeed, one of those ironies of fate, of
which the world is so full, that he did not live to see this
demonstration—for it is no less—of the truth of his most original and
elevating views; elevating they may be well called, since they allow to
the animal world an æsthetic faculty, the power, once thought
exclusively human, of appreciating beauty. It is curious how willing
many are to exalt humanity at the expense of all other beings. The
higher faculties they like, and perception of the beautiful they like,
and spirituality—especially in love—they like very much indeed; but they
only like these things in their own species. That is to say, conceit
lies at the bottom of all this exaltation. Such man-worshippers would
not have more of a good thing in the world, but less, so that they may
have all there is of it. On such grounds the war against evolution was
waged, and its last struggles are against sexual selection. The body has
been given up, but the spirit, which touches us yet more nearly, is
still fiercely defended.
In _Hasarius Hoyi_ “the sexes are very different, the male being the
more conspicuous of the two. In his dances, the male has several
movements. Most commonly he goes from side to side, with his first legs
obliquely up. At other times he twists the abdomen to one side, and,
bending low on the other, goes first in one direction for about two
inches, and then, reversing, circles to the opposite point. The females
are very savage, especially with each other, and even the members of the
sterner sex are not always free from danger when paying their
preparatory addresses. Once we saw a female eagerly watching a prancing
male, and, as he slowly approached her, she raised her legs as if to
strike him, but he, nothing daunted by her unkindly reception of his
attentions, advanced even nearer, when she seized him and seemed to hold
him by the head for a minute—he struggling. At last he freed himself and
ran away.”[133] Yet “this same male, after a time, courted her
successfully.” That so much savagery has to be overcome in the female,
and finally is overcome by these dances, shows how powerfully she must
be affected by them. Of another and previously undescribed species, “a
dozen or more males, and about half as many females,” were found by the
authors “assembled together” under natural conditions. “The males were
rushing hither and thither, dancing opposite now one female and now
another. Often two males met each other, when a short passage of arms
followed. The males were very quarrelsome, and had frequent fights, but
we never found that they were injured. Indeed, after having watched
hundreds of seemingly terrible battles between the males of this and
other species, the conclusion has been forced upon us that they are all
sham affairs, gotten up for the purpose of displaying before the
females, who commonly stand by, interested spectators.”[133]
Then there is a small ant-like species, who, “unlike most of the _Attid_
males, keeps all his feet on the ground during his courtship. Raising
himself on the tips of the posterior six, he slightly inclines his head
downwards by bending his front legs, their convex surface being always
turned forward. His abdomen is lifted vertically, so that it is at a
right angle to the rest of his body. In this position he sways from side
to side. After a moment he drops the abdomen, runs a few steps nearer
the female, and then tips his body and begins to sway again. Now he runs
in one direction, now in another, pausing every few moments to rock from
side to side and to bend his brilliant legs, so that she may look full
at them.”[133] What can be clearer than this? And here, indeed, the
authors remark: “We were much impressed by the fact that the attitude
taken by the males served perfectly to show off their fine points to the
female. We had never known the male of this species until the day that
we caught this one and put him into the mating-box, and it was while
studying his courtship that we noticed how he differed from the female
in his iridescent first legs. He could not have chosen a better position
than the one he took to make a display.”[133]
Elsewhere, in another experiment with the same species, the authors,
after remarking that if these specially modified front legs were held in
any other way the effect of the flattened and iridescent surface would
be lost, go on to say: “This is a good example of what we have again and
again observed in the courtship of the _Attidæ_: that whatever fine
points of colour or structure the male possesses, his actions before the
female display them to the very best advantage. In whatever part the
special merit may lie, he sedulously strives to bring it to the notice
and impress its beauty upon the mind of the female to whom he is paying
his addresses.”[133] As for the female, she is throughout described as
watching the male eagerly and with the greatest interest, and that this
interest is not always felt from the first, but is aroused by degrees,
becoming, at last, so strong as to suspend for a time the natural
inclination to assault and eat the wooer, is all the more significant.
That there are dangers in these courtships there has been some
indication, “but worse remains behind.” _Phidippus rufus_ was caught
once and eaten in an unguarded moment, and whilst _Phidippus morsitans_
was waving his particularly handsome first pair of legs, “thickly
adorned with white hairs,” precisely the same thing happened to him.
Still, on the whole, such incidents are exceptional.
Particularly interesting is the account given of the courtship of
_Saitis pulex_, a male of which species was introduced into a box
already occupied by a female. “He saw her as she stood perfectly still,
twelve inches away; the glance seemed to excite him, and he moved
towards her; when some four inches from her he stood still, and then
began the most remarkable performances that an amorous male could offer
to an admiring female. She eyed him eagerly, changing her position from
time to time, so that he might be always in view. He, raising his whole
body on one side, by straightening out the legs, and lowering it on the
other by folding the first two pairs of legs up and under, leant so far
over as to be in danger of losing his balance, which he only maintained
by sidling rapidly towards the lowered side. The palpus, too, on this
side, was turned back to correspond to the direction of the legs nearest
it. He moved in a semicircle for about two inches, and then instantly
reversed the position of the legs and circled in the opposite direction,
gradually approaching nearer and nearer to the female. Now she dashes
towards him, while he, raising his first pair of legs, extends them
upward and forward as if to hold her off, but withal slowly retreats.
Again and again he circles from side to side, she gazing towards him in
a softer mood, evidently admiring the grace of his antics. This is
repeated until we have counted one hundred and eleven circles made by
the ardent little male. Now he approaches nearer and nearer, and when
almost within reach, whirls madly around and around her, she joining and
whirling with him in a giddy maze. Again he falls back and resumes his
semicircular motions with his body tilted over; she, all excitement,
lowers her head and raises her body so that it is almost vertical; both
draw nearer”[133]—and the male, now, for some short period is in no
danger of being eaten.
Lastly—for this must be the last example—we have a species—_Astia
vittata_—in which the male is represented by two differing forms, each
of which dances before the female in its own particular way. One of
these forms is red, like the female, which he resembles in other
respects, so that this must be taken as the original specific type. The
other, which has evidently been developed from it, in deference to the
æsthetic preferences of the female, is black, with the special adornment
of three tufts of hair on his head, or thereabouts, that part of a
spider which is termed the cephalothorax. These tufts stick bolt
upright, rising together, but separating about half-way up, and give to
their fortunate possessor—for, as we shall see, he is fortunate—a very
spruce and dapper appearance. Looked at dispassionately, if one can do
that, they are certainly as handsome as moustaches, and there is no
reason in the nature of things why they should not be admired as much.
So, indeed, they are, and that the admiration bestowed upon each is of
an equally high nature I, at any rate, see no reason to doubt.
The following description will show what a spider with moustaches can
achieve: “The _vittata_ form, which is quite like the female, when he
approaches her raises his first legs either so that they point forward
or upward, keeping his palpi stiffly outstretched, while the tip of his
abdomen is bent to the ground. This position he commonly takes when
three or four inches away. While he retains this attitude he keeps
curving and waving his legs in a very curious manner. Frequently he
raises only one of the legs of the first pair, running all the time from
side to side. As he draws nearer to the female he lowers his body to the
ground, and, dropping his legs also, places the two anterior pairs so
that the tips touch in front, the proximal joints being turned almost at
a right angle to the body. Now he glides in a semicircle before the
female, sometimes advancing, sometimes receding, until at last she
accepts his addresses. The _niger_ form, evidently a later development,
is much the more lively of the two, and whenever the two varieties were
seen to compete for a female the black one was successful.”[133]
Here, surely, is a final answer to those assertions as to indifference
on the part of the female, which, though made in the teeth of
probability, are often, on account of the difficulties of observation,
almost impossible to disprove. Here are two kinds of males, one lively
and with moustaches, the other not so lively and without them; as the
first is always, or even, say, generally chosen, his appearance must be
preferred. Were it only his liveliness, as Dr. Wallace has suggested,
why should he have acquired another dress as well as another dance? or,
if the female can have a choice as between liveliness and slowness, as
between a jig and a minuet, why, in Heaven’s name, should she not have
one as between one get-up and another? Sexual selection might, I think,
be put to the test in this one species with its two male forms. Let but
a sufficient number of courtships be observed and reported on, and if
_niger_, in a large percentage of them, wins the day, choice on the part
of the female—the only link in the chain of evidence which it is at all
possible to deny—is a proved thing.
But to continue: “He—_niger_—is bolder in his manners (no wonder he
prevails), and we have never seen him assume the prone position, as the
red form did, when close to the female. He always held one or both of
the first legs high in the air, waving them wildly to and fro; or when
the female became excited, he stood perfectly motionless before her,
sometimes for a whole minute, seeming to fascinate her by the power of
his glance”[133]—greatly aided probably by the three tufts of hair
showing through the archway of the uplifted legs. Here, again, too, as
in some of the other species—perhaps all—“although the males were
continually waving their first legs at each other, their quarrels were
harmless. It was quite otherwise with the females, since they not only
kept the other sex in awe of them, but not infrequently in their battles
killed each other.”[133] As the males cannot win the females by
fighting, what have they to contend with effectively except these
curious, elaborate, and most interesting displays, the purpose of which
is so excessively obvious? On the other hand, the fact that the females
yield, almost against their nature, to these displays, that they are
slowly and gradually won through their means, is proof positive that
they like them, and if so, how is it possible that they should not like
one more or less than another? What, in fact, is choice but a greater or
less reaction to this stimulus or to that? The initial absurdity of
laying claim to a monopoly of such a capacity as this, either in our
matrimonial affairs, or any other matter in which animals participate,
has not been sufficiently dwelt upon.
Professor Poulton, in considering this case of _Astra vittata_ with its
two male forms, one of which is always chosen by the female in
preference to the other, remarks (with his own italics), “It must be
admitted that these facts afford the _strongest support_ to the theory
of Sexual Selection.”[134] He thus endorses—as anyone, I think, not
hard-set the other way, must endorse—the opinion of the authors of the
paper that “in the _Attidæ_ we have conclusive evidence that the females
pay close attention to the love dances of the males, and also that they
have not only the power, but the will, to exercise a choice among the
suitors for their favour,”[135] to which he adds this rider:
“Remembering that this conclusion has only been reached in the _Attidæ_
by the closest study, I think we may safely explain the smaller
confidence with which we can speak of other animals by the want of
sufficiently careful and systematic investigation.”
The process of the narrative having led, in the last chapter or two, to
a discussion of some of the ways in which insects become shaped and
coloured through natural selection, sexual selection seemed marked out
as the subject for this one. The reason why I have filled it with
extracts from a certain very interesting paper has been a better one
than that of saving myself trouble. That paper—the most important one
perhaps that has ever been written on the subject—is a wonderful
confirmation of Darwin’s views, but Darwin, as it appears to me, has not
benefited by it in the way that he ought to do in the popular mind.
There is no work that I know of, written upon merely popular lines, that
brings these facts forward, and yet I feel sure that to large numbers of
people, who yet do not care to read books avowedly scientific, they must
be extremely interesting, not only in themselves, but as allowing them
both to form a judgment on the subject, and on the correctness or
otherwise of Darwin’s views—for Darwin is an interesting and picturesque
figure far beyond the close borough of science.
Now the general more intelligent public who read, perhaps, widely, but
not very deeply or very specially, know that Darwin believed in two
forces—natural and sexual selection—by the joint action of which,
species, as he held, had been gradually modified and evolved, and they
know that the former of these two has been accepted by science, but that
to the latter there has been much more opposition, and that it is not—or
is not supposed to be—established like the other. Many, perhaps, may
have read Dr. Wallace’s _Darwinism_, a work in which Darwin’s most
distinctive and original view—that one whose conception, apparently, he
shared with nobody and on which he based much of the argument contained
in his _Descent of Man_—is considered and rejected in a way which makes
the title of the book misleading, surely, if not a somewhat comically
ludicrous misnomer. All those who have read it, as well as many who have
not, will be interested—they cannot fail to be—in the wonderful record
of spider courtships contained in these extracts, and having reflected
on them, they will, if I mistake not, be much more impressed with the
arguments _for_ this part of Darwinism than they were with those brought
against it in the book of that name.
All these latter arguments, by the way—the languor of swallows as
against the vitality of parrots, trogons, etc.—were well known to Darwin
himself; and as no one was, at the same time, more impartial in
considering, and more capable of correctly estimating, facts hostile to
his own theories, or which, at first sight, might seem to be so, it may
not be out of place to end this chapter with a reference to what he
thought of them. This we may gather from a statement contained in a
paper—the last, presumably, ever written by him—which was read before
the Zoological Society but a few hours before his death, and which is as
follows: “I may, perhaps, be here permitted to say that, after having
carefully weighed, to the best of my ability, the various arguments
which have been advanced against the principle of sexual selection, I
remain firmly convinced of its truth.”
-----
Footnote 130:
Tropical Nature, p. 97.
Footnote 131:
Malay Archipelago (1898), p. 331.
Footnote 132:
Observations on Sexual Selection in Spiders.
Footnote 133:
Occasional Papers of the Natural History Society of Wisconsin, vol.
i., Nos. 1, 2, and 3.
Footnote 134:
The Colours of Animals.
Footnote 135:
Occasional Papers of the Natural History Society of Wisconsin, vol.
i., Nos. 1, 2, and 3.
------------------------------------------------------------------------