River Out Of Eden - Richard Dawkins

On Argument from personnel incredulity Gradual Change...

Creationism has an enduring appeal, and the reason is not far to seek. It is not, at least for most of the people I encounter, because of a commitment to the
literal truth of Genesis or some other tribal origin story. Rather it is that people discover for themselves the beauty and complexity of the living world and
concluded that it obviously must have been designed. Those creationists who recognize that Darwinian evolution provides at least some sort of alternative to
their scriptural thoery often resort to a slightly more sophisticated objection. They deny the possibility of evolutionary intermediates. "X must have been
designed by a creator," people say, "Because half of X would not work at all. All part of X must have been put together simultaneously; they could not have
gradually evolved" For instance, on the day I began writing this chapter I happened to receive a letter. It was from an American minister who had been an
atheist but was converted reading an article in National Geographic. Here is an extract from that letter.

"The article was about the amazing adaptations that orchids have made to their environments in order to propagate successfully. As I read I was particularly
intrigued by the reproductive strategy of one species, which involved the coopertation of a male wasp.. Apparently the flower resembled very closely the
female of this species of wasp, including having an opening in the proper place, so that the male wasp might just reach, by copulating with the flower, the
pollen produced by the blossom. Flying on to the next flower the process would be repeated, and thus cross-pollination take place. And what made the
flower attractive to the wasps in the first place was that it emitted pheromones [specific chemical attractants used be insects to bring sexes together]
identical to that of the female wasp. With some interest I studied the accompanying picture for a minute or so. Then, with a terrific sense of shock, I realized
that in order for that reproductive strategy to have worked at all, it had to be perfect the first time. No incremental steps could have accounted for it, for if
the orchid did not look and smell like the female wasp, and have an opening suitable for copulation with the pollen within the perfect reach of the male
wasp’s reproductive organ, the strategy would have been a complete failure.

I will never forget the sinking feeling that overwhelmed me, because it became clear to me in that minute that some kind of God in some kind of fashion must
exist, and have an ongoing relationship with the process by which things come into being. That in short, the creator God was not some antediluvian myth,
but something real. And, most reluctantly, I also saw at once that I must search to find out more about that God."

Others, no doubt, come to religion by different routes, but certainly many people have had an experience similar to the one that changed the life of this
minister. They have seen, or read about, some marvel off nature. This has, in a general way, filled them, with awe and wonderment, spilling over into
reverence. More specifically, like my correspondent, they have decided that this particular natural phenomenon - a spider’s web, or an eagles eye or wing,
or whatever it is - cannot have evolved by gradual stages, because the intermediate, half formed stages could not have been good for anything. The purpose
of this chapter is to destroy the argument that complicated contrivances have to be perfect if they are to work at all. Incidentally, orchids were among
Charles Darwin’s favorite examples, and he devoted a while book to showing how the principle of gradual evolution by natural selection triumphantly meets
the ordeal of explaining "The various Contrivances by which Orchids are Fertilized by Insects"

The key to the ministers argument lies in the assertion that "in order for that reproductive strategy to have worked at all, it must have been perfect the first
time. No incremental steps could account for it" The same argument could be made, and frequently has, for the eye, and I’ll return to this in the course of
the chapter.

What always impressed me whenever I hear this kind of argument is the confidence in which it is asserted. How, I want to ask the minister, can you be so
SURE that the wasp-mimicking orchid (or the eye, or whatever) wouldn’t have worked unless every part of it was perfect and in place, Have you in fact,
given the matter a split second’s thought? Do you actually know the first thing about orchids, or wasps, or the eyes in which wasps look at females and
orchids? What emboldens you to assert that wasps are so hard to fool that the orchids resemblance would have to be perfect in all dimensions in order to
work?

Think back to the last time you were fooled by some chance resemblance. Perhaps you raised your hat to a stranger in the street, mistaking her for an
acquaintance. Film stars have stand-in stuntman or stuntwoman to fall off horses or to jump off cliffs in their stead. The stuntman’s resemblance to the star is
usually extremely superficial, but in the fleeting action shot it is enough to fool an audience. Human males are roused to lust by pictures in a magazine. A
picture is just printing ink on paper. It is two-dimensional, not three,. The image is only a few inches high. It may be a crude caricature consisting of a few
lines, rather than a life-like representation. Yet it can still arouse a man to erection. Perhaps a fleeting view of a female is all a fast flying wasp can expect to
get before attempting to copulate with her. Perhaps male wasps notice only a few key stimuli anyway.

There is every reason to think that wasps might even be easier to fool than humans. Sticklebacks certainly are, and fish have bigger brains and better eyes
than wasps. Male sticklebacks have red bellies, and they will threaten not only other males but also crude dummies with red "bellies" My old maestro, the
Nobel Prize Winning ethologist Niko Tinbergen told a famous story about a red mail van that drove past the window of his laboratory, and how al the male
sticklebacks rushed toward the windows side of their tanks and vigorously threatened it. Female Sticklebacks that are ripe with eggs have conspicuously
swollen bellies. Tinbergen found that an extremely crude, vaguely elongated, silvery dummy, looking nothing like a stickleback to our eyes but possessed of
a well rounded "belly", evoked full mating behavior from the males. More recent experiments in the school of research founded by Tinbergen have shown
that a so called sex bomb, a pear shaped object, rounded plumpness personified but not elongated and not fishlike by any stretch of the (human)
imagination - was even more effective in arousing the lust of the male stickleback. The stickleback "sex bomb" is a classic example of a supernormal
stimulus-a stimulus even more effective than the real thing. As another example, Tinbergen published a picture of an oyester catcher trying to sit on an egg
the size of an ostrich egg. Birds have bigger brains and better eyesight than fish-and a fortiori than wasps-yet oyester catchers apparently "think" that an
ostrich sized egg is a superlative object for incubation.

Gulls, geese and other ground-nesting birds have a stereotyped response to an egg that has rolled out of the nest. They reach over and roll it back with the
underside of their bill. Tinbergen and his students showed that gulls will do this not just to their own eggs but to hen’s eggs and even wooden cylinders or
cocoa tins discarded by campers. Baby herring gulls get their food by begging from their parents; they peck at the red spot on the parent’s bill, stimulating
the parent to regurgitate some fish from its bulging crop. Tinbergen and a colleague showed that crude cardboard dummies of parent’s heads are very
effective in provoking begging behavior from the young. All that is really necessary is a red spot. As far as the baby gull is concerned, its parent is a red
spot. It may well see the rest of it’s parent, but that does not seem important.

This apparently restricted vision is not confined to baby gulls. Adult black headed gulls are conspicuous because of their dark face masks. Tinbergen’s
student Rober Mash investigated the importance of this to other adults by painting wooden dummy gull heads. Each head was stuck on the end of a
wooden rod attached to electric motors in a box so that, by remote control, Mash could raise or lower the head of the gull and turn it right or left. He would
bury the box near a gull nest and leave it with the head sagely out of sight beneath the sand. Then, day after day, he would visit a blind near the nest and
observe the gulls reaction to that dummy head when it was raised and turned this way or that way, The birds responded to the head and to its turning just as
though it were a real gull, yet it was only a mock up on the end of a wooden rod, without any body, without legs wings or tail, silent and without moment
apart from pretty unlifelike ,robotic rising, rotating and lowering. To a black headed gull, it deems, a threatening neighbor is little more than a disembodied
black face. No body, no wings, or anything else seem to be necassary.

Just to get into the blind to observe the birds, Mash, Like generations of ornithologists before him and since, exploited a long-known limitation of the bird
nervous system: birds are not natural mathematicians. Tow f you go to the blind, and one of you leaves it, Without this trick, the birds would be weary of the
blind knowing that somebody had entered it. But if they see one person leave, they assume that both have left. IG a bird can not tell the difference between
one person and two is it all that surprising that a male wasp might be fooled by an orchid that bore less than prefect resemblance to a female.

One more bird story along these lines, and it is a tragedy. Turkey mothers are fierce protectors of their young. They need to protect them against nest
marauders like weasels or scavenging rats. The rule of thumb a turkey mother uses to recognize nest robbers is a dismayingly brusque one: in the vicinity of
your nest, attack anything that moves unless it makes noise like a baby turkey. This was discovered by an Austrian zoologist named Wolfgang Schleidt.
Schleidt once had a mother turkey that savagely killed all her own babies. The reason was woefully simple: she was deaf. Predators, as far as the turkey’s
nervous system is concerned, are defined as moving objects that do not emit a baby’s cry. These baby turkeys, though they looked like baby turkeys,
moved like baby turkeys, and ran trustingly to their mother like baby turkeys, fell victim to the mothers restricted definition of a "predator" She was
protecting her own children against themselves, and she massacred them all.

In an insect echo of the tragic story of the turkey, certain of the sensory cells in honeybee antennae are sensitive to only one chemical, oleic acid. Toleic
acide is given off by decaying bee corpses, and it triggers that bees’ "Undertaker" behavior, the removal of dead bodies from the hive. If an experiment
paints a drop of oleic acid on a live bee, the wretched creature is dragged off, kicking and struggling and obviously very much alive, to be thrown out with
the dead.

Insect brains are much smaller than turkey brains or human brains. Insect eyes even the big compound eyes of dragonfly, possess a fraction of the acuity of
our eyes or bird eyes. Quite apart from this, it is known that insect eyes see the world in a completely different way from our eyes. The great Austrian
zoologist Karl von Frisch discovered as a young man that they are blind to red light but they can see-and see in it’s own distinct hue-ultraviolet light, to
which we are blind. Insect eyes are much preoccupied with something called "flicker":, which seems-at least to a fast moving insect-to substitute partially for
what we would call "shape: Male butterflies have bee seen to "court" dead leaves fluttering down from trees. We see a female butterfly as a pair of large
winds flapping up and down. A flying male butterfly sees her, and courts her, as a concentration of "flicker" You can fool him with a stroboscopic lamp,
which doesn’t move but just flashed on and off. If you get the flickering rate right, he will treat it as if it were another butterfly flapping its winds at that rate.
Stripes, to us, are a static pattern. TO an insect as it flies past, stripes appear to "flicker" and can be mimicked with a stroboscopic lamp flashing at the right
rate. The world as seen through an insect'’ eyes is so alien to us that to make statements based on our own experience when discussing how "perfectly" an
orchid needs to mimic a female wasp’s body is a human presumption.

Wasps themselves were the subject of a classic experiment, originally done by the great French naturalist Jean Henri Fabre and repeated by various other
workers, including members of Tinbergen’s school. The female digger wasp returns to her burrow carrying her stung and paralyzed prey. She leaves it
outside the burrow while she enters, apparently to check that all is well before she reappears to drag the prey in.. While she is in the burrow, the
experimenter moves the prey a few inches away from where she left it. When the wasps resurfaces, she notices the loss and quickly relocates the prey. She
then drags it back to the burrow entrance. Only a few seconds have passed since she last inspected the inside of the burrow. We think that there is really no
good reason why she should not proceed to the next stage in her routine. drag the prey inside and be done with it. But her program has been reset to an
earlier stage. She dutifully leaves the prey outside the burrow again and goes inside for yet another inspection. The experimenter may repeat this charade
forty times, until he gets bored. The wasp behaves like a washing machine that has been set back to an early stage in it’s program and doesn’t "know" that
is has already washed the clothes forty times without a break. The distinguished computer scientists Douglas Hofstadter has adopted a new adjective,
"sphexish" to label sick inflexable, mindless automatism. (Sphex is the name of one representative of digger wasp._ At least in some respects, then, wasps
are easy to fool. It is a very different kind of fooling from that engineered by the orchid. Nevertheless, we must beware if using human intuition to conclude
that "in order for that reproductive strategy to have worked at all, it had to be perfect the first time."

Richard Dawkins - River Our Of Eden

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