Part I
If anyone ever tells you "evolution," just say "sylvia
curruca." That should put an end to the conversation
rather quickly, unless of course you're the one who wants to
do the convincing.
"Who's sylvia curruca?" you ask.
It's not who; it's what. Sylvia curruca is the
scientific name for a little bird whose common name is the
lesser whitethroat, a warbler (a type of songbird) that
spends its summers in northern Europe and winters in sub-
Saharan Africa. The point is that this bird can do some truly
astonishing feats of navigation which make the proposition of
evolution by chance virtually impossible to entertain.
Essentially, this little bird has a map of the night sky
embedded in its genes. To suppose that this map got there by
chance requires an incredible, and totally unwarranted,
amount of faith in what chance can and cannot do. So if you
ever find that you need to argue against evolution, it's a
handy little bird to remember.
But let's not start with sylvia curruca. Its feats of
navigation may represent an extreme capability that is not
found in most other migratory animals. Rather let's begin by
looking at a few slightly less astounding facts regarding
animal migration and navigation. Even these simpler facts are
amazing and worth knowing about.
A good place to begin is with the Arctic tern. It currently
holds the world record for distance of migratory travel.
During summer in the northern hemisphere, it nests in the
Arctic. Come autumn, it heads south to enjoy summer again in
the Antarctic. The total distance it travels round trip on
its migratory journeys is close to 25,000 miles.
There is as yet no direct evidence that the tern's tendency
to fly from north to south and back again is an inherited
trait. Terns travel in flocks and the young fly with the
adults. So the urge to fly, and the usefulness of flying,
from one end of the globe to the other may be something that
is learned by these birds and not purely an instinct.
But even if so, one must still wonder how the whole thing got
started. What ever prompted any bird to fly about 12,000
miles in search of food or a more favorable climate? How did
it know that it would be rewarded at trip's end?
Moreover, if other migratory animals are a guide, there is
good reason to suppose that the tern is compelled by its
genetic makeup to fly where it does and that its behavior is
instinctive, not knowledge learned from others. If so, the
question of why and how it does it, is all the more
compelling.
In many migratory species, the young that are born in the
spring or summer make their first migratory trip without
parental guidance. And they travel to exactly the place where
the adults winter, even though they leave after all the
adults have already gone.
For example, many species of cuckoo have the nasty habit of
depositing their eggs in nests belonging to other species of
birds. They abandon their young, expecting that they will be
raised by others, as indeed they are.
The adult cuckoos generally leave to their winter grounds
well before the newborn cuckoos have matured or often have
even hatched. Nevertheless, the newborn birds have an inborn
guidance system which enables them to unhesitatingly arrive
at the same winter grounds to which their elders have gone,
making the trip about as quickly as the mature adults that
have been there before.
The travel of one species, the New Zealand bronze cuckoo, is
a case in point. After breeding in New Zealand, the adult
birds fly about 1500 miles west across the Tasman Sea to
Australia. After resting for a few days, they continue
northwest for another 2000 miles, up along the east coast of
Australia and over the Coral Sea, to New Guinea. From there
they continue northeast for a few hundred miles more, again
over open sea, to their final destination, a group of islands
called the Bismarck Archipelago.
Cuckoos, by the way, are land birds. They cannot swim. So
unless the entire flight over water is made in one trip, the
birds are doomed. The genetic program thus has to be quite
precise. Should it instruct travel of only 1000 miles west
from New Zealand or in the wrong direction or even at a bad
angle, these particular cuckoos would not be here for anyone
to write about.
In fact the program is so good that young cuckoos who have
never even heard of the Bismarck Archipelago are able to find
the darn thing (it's only about 3500 miles away and a tiny
speck on any map) a few weeks after they are born -- totally
without any guidance from the adults.
What is true for cuckoos is also true for species of birds
that flock together to migrate. In many cases, such birds as
well have the migration route as an inherited program, not as
something that is learned by experience. We know this from
experiments that have been conducted on a variety of such
birds.
Young birds were raised in isolation from other birds. These
"naive" birds were then released well after all the other
members of the species had left for their winter grounds. In
virtually all reported cases, the naive birds, which had
never been taught where to go and how to get there, ended up
in the same wintering locales as their ancestors.
Inherited migratory behavior with detailed information about
routes of migration is not restricted to birds. Very many
other animals migrate: mammals, reptiles, fish, insects. In a
good number of cases, young, inexperienced members of the
species are capable of retracing the route taken by adults or
finding their way back to ancestral homes.
Two of the most striking examples of this sort of behavior
are presented by certain species of freshwater eel and by the
Monarch butterfly. The facts in both these cases are
absolutely astonishing. Details can be found in any good book
on animal migration.
Consider the implication of this general phenomenon. Let's
ignore for now the issue of exactly how these animals
navigate to their migratory goal. That is a separate problem
which is in some ways even more spectacular and will be
considered in a follow-up article.
For now let us focus merely on the notion of the existence of
a genetic program which instructs an organism to migrate -- a
program which essentially says that for the animal's survival
it must leave one locale, and which also maps out precisely
where it must go.
Take the case of the Arctic tern. Assuming that its migratory
behavior is governed by its genes (which in all likelihood it
is), one must wonder how DNA was able by chance to hit upon a
plan of migration that works so perfectly.
DNA has no knowledge about the outside world. Yet it has
chanced upon a set of instructions that comports with
geographic reality and that sends a bird flying more than ten
thousand miles to a destination that is just right for it.
The life cycle of the Arctic tern requires it to live at the
two extremes of the globe; probably no other place on earth
would do for this particular bird. How did randomness happen
upon a set of instructions that guides terns to these
locations?
And DNA has to accomplish much more. Not only
must the genes supply a flight plan, they also must provide
for a whole complex of physical and behavioral changes that
enable the tern to actually make the trip.
The tern's body is especially adapted for extremely long
distance flights. It is lightweight, with long slender wings
designed for energy-saving flight at low speeds, including
hovering. It instinctively chooses the most efficient flight
speed and behavior in relation to wind.
In preparation for the trip, the bird's body begins to store
fat for weeks and sometimes months before the actual trip is
taken. Migratory birds held in captivity under perfectly
uniform conditions with no clue about seasons, automatically
begin to gain weight at just the right time.
Then, when it comes time to migrate, the birds flock together
at the perfectly appropriate time. Birds that have been
scattered over hundreds of miles of Arctic terrain converge
to predetermined meeting places exactly on cue.
In other words, a panoply of instinctive behaviors come
together to make the whole thing work just right.
And isn't it incredibly lucky for DNA to have mapped out the
route of the New Zealand bronze cuckoo?
"Head west (precise angle provided) for 1500 miles until you
reach land. Rest and feed for a few days to gather strength
for the next leg of the trip. (You're dead if you don't,
since you cannot swim.) Travel 2000 miles northwest (again
precise angle provided) to the next major island. Then turn
northeast (of course, precise angle provided again) for
several hundred miles until you get to a group of small
islands. (Incidentally, you'll find your parents there
because their genes also tell them to do the same thing)."
Imagine that! There actually is an island suitable for cuckoo
habitation at the end of this flight plan. How could DNA, by
chance, without any knowledge of geography or even that there
is a planet Earth out there, ever have devised a flight plan
as precise as this?
One does not have to be a rocket scientist or do fancy
calculations to recognize that for blind chance to have
devised a set of instructions that even remotely resemble
what has just been presented seems more than what one would
normally be willing to accept.
Of course, it is tempting to argue that maybe it's not
chance. Maybe somehow DNA is impacted by the outside world.
Maybe somehow the outside world impinges on the organism and
causes its DNA to form in a certain way.
But, according to today's science, such a proposition is
about as heretical as one can get. It's Lamarckism all over
again. Any good evolutionist and biologist will tell you this
is precisely what Darwin's theory came to counter. Today,
such a theory is simply not at all accepted in any shape,
manner or form.
The reason for this is that the central dogma of biology, and
by inference of evolution as well, is that DNA is totally
blind. It cannot know anything about the outside world.
Information in the cell travels only in one direction, from
DNA to end products, never the other way around. Without
positing divine intervention, changes to DNA can occur only
by chance. Nothing else.
So to believe in evolution of necessity means believing that
DNA gets extremely lucky sometimes, that after a bit of trial
and error, DNA will hit the jackpot. It will, evolution says,
purely by chance, by total randomness, produce flight plans
for birds and insects that are necessary for their
survival.
And one must also believe that DNA will do it over and over
again, for the Arctic tern and for the New Zealand bronze
cuckoo and the eel and butterfly and hundreds or thousands of
other migratory species.
And purely by chance, these flight plans actually work. They
enable newborn land birds to fly thousands of miles over open
ocean to hit precisely a dot of an island in a vast, uniform,
uncharted sea.
The facts of animal migration and navigation are so
overwhelming that scientists and authors who write about the
subject, and who generally believe in evolution, tend to get
carried away. They use terms that one does not generally see
in biology, or for that matter in any other scientific
subject. One repeatedly encounters words like, "remarkable,"
"astonishing," "incredible," "spectacular," "amazing."
And there are no real answers to the basic questions on how
all this could have happened. Articles on the subject freely
admit that in many cases there is as yet "no viable
hypothesis" to explain how animals do it.
The abilities of animals to navigate and migrate are
"mysterious," "intriguing." In fact, one author even referred
to the abilities of one bird as a "miracle of navigation."
Bli neder, part II of this article will look at some
of these miracles of animal navigation. That's when sylvia
curruca will get a chance to show off.
