by Karl W. Giberson
On rare occasions, humans are born with tails—
real functioning tails
that can even be “wagged” via voluntary muscles contractions in
response to emotional stimuli. Although the birth of a baby with a tail
is frightening for parents and typically requires surgery, the
remarkable human tail is an important part of the even more remarkable
tale of our origins—namely evolution.
Human tails are
part of the evolutionary baggage that we carry in our bodies, leftover
from our ancestors. As we evolved through time, responding to different
environmental pressures, natural selection pruned and edited, making our
ancestors better at some things—like talking—while ignoring skills and
characteristics that became less relevant in new contexts—like smelling.
Unfortunately, natural selection has no mechanism to eliminate useless
features, but traits that become irrelevant can atrophy or get co-opted
for some other task since there is no longer a disadvantage when those
features show up in a weakened form.
We
carry the evidence of this long history in our bodies—features useful
to our ancestors but, for various reasons, not to us. We have goose
bumps, for example, that our hairy ancestors used to make their fur
stand up straighter when they needed extra warmth or wanted to look
menacing. We have muscles that some of us, including me, can use to
wiggle our ears, which would be useful for locating sounds if our
hearing was more acute. We have a bunched-up third eyelid in the corner
of our eye that provided a transparent eye covering for our ancestors,
allowing them to “blink” without have to fully shut down their vision.
We
call this useless anatomical baggage “vestigial.” Every species has
some of it. Flightless birds have non-functional wings. Blind fish
living in dark caves have eyes that can’t see. Most pythons have
atrophied useless pelvises floating inside their abdomens, not connected
to anything.
Other
historical markers can be found in our genes. We have a gene to make
Vitamin C but, unfortunately for those sailors who died from scurvy, it
is broken, so we have to get Vitamin C from our food. Chimpanzees and
orangutans have the same broken gene, which can only have been inherited
from our common ancestor for whom it was functional, as it still is for
many animals.
Every human
being embodies the history of our species in the form of stuff inherited
from the past. We are walking museums of natural history but some of
the exhibits are rather dreadful. And every other species—and there are
millions of them—also carry vestiges of its life history.
These
dreadful exhibits are the undeniable proof of evolution, linking
present species with their ancestors in the clearest of ways. From
Darwin to the present, the existence of bad, sinister, unintelligent
design has provided powerful evidence that species were not created in
their present forms but must have evolved over time—and evolved in such a
way that the designs we encounter in ourselves and other species today
are often the opposite of intelligent.
The
presence of so much “unintelligent” design across so many species
should demolish the central claims of the Intelligent Design movement.
For every “irreducibly complex” thing with more design than can be
accounted for by present science, there are a thousand things in nature
with inferior levels of design. For every arrow pointing toward a
“designer,” there are a thousand arrows pointing the other way.
How then, does the Intelligent Design movement (ID) persist, in the face of so much damning contrary evidence?
To
understand this strange phenomenon, we have to appreciate that ID
handles scientific evidence the way lawyers handle evidence in legal
cases, namely paid to come to a foregone conclusion, no matter how
poorly supported. If 1,000 people saw you commit the crime and Joe saw
someone else do it, Joe’s testimony is the only one that matters to your
defense lawyer. When someone from the 1,000 witnesses appears on the
stand, your lawyer tries to make their integrity appear suspect, and to
call their competence into question.
The
weakness of any case becomes clear when the logic used to make the
arguments is strained, selective and irrelevant. I have watched such
tortured reasoning—much of it by a lawyer—in the aftermath of my debate
with ID theorist Stephen Meyer a few weeks ago.
In
the debate, I emphasized the problem of bad design that I outlined
above, mentioning that bad design is common in nature and poses serious
problems for ID. I gave some examples of bad design and showed a
picture of an infant with a well-formed tail to illustrate one example.
The
response was exactly what one would expect from lawyers. Rather than
noting that apparent bad design was common and needed to be addressed by
ID—a point I have made in several debates with creationists and ID
theorists and has always been met with silence—the response focused
exclusively on the particular example of the human tail, as if that is
all that needs to be explained. One ID spokesperson, David Klinghoffer,
claimed—falsely and absurdly—that I presented it a “proof of Darwinian
evolution,” on which I was “very stuck.” (It is a piece of evidence,
which is quite different than a proof.) Klinghoffer then attempted to
undermine the argument from bad design by undermining the image I had
used to illustrate my point. The image came from
an article on Cracked.com which Klinghoffer
described as the “vestigial online presence of an old satirical magazine, now defunct, a knockoff of
Mad.”
But where the image came from is of zero import; Klinghoffer’s point
does absolutely nothing to undermine the universally accepted and fully
documented reality that human babies are occasionally born with tails.
Google has more than a million hits—and countless images—for the term
“babies born with tails.”
Casey
Luskin, also of the Discovery Institute, published several pieces on
humans with tails that at least engaged the phenomena of tails, instead
of the pedigree of the image I used. But rather than address the actual
question on the table—how can ID account for bad design?—he focused
exclusively on creating a tenuous speculation that there might be no
such thing as genuine human tails.
Note
the reasoning process here, keeping in mind that 1) there is a
consensus in the scientific community that humans are sometimes born
with real tails that are evolutionary throwbacks; 2) the gene for tails
has been located in the human genome is
the same one that mice use to produce their tails; and 3) the issue is not the human tail, but the problem of bad design in nature.
Luskin—a
lawyer—starts by noting that there is “still much debate over why tails
arise during development,” but fails to mention that this debate is not
about whether the tail sometimes represents the reappearance of an
ancestral feature. He notes that “at least one paper” recognizes that
the cause of the tail is “poorly understood.” But his next logical leap
is breathtaking.
The
unwanted appendages attached to babies are classified as either “true
tails,” which I have been discussing, or “pseudotails,” which are birth
defects that only resemble tails, like a blob of flesh hanging
from the lower back. The distinction between the two is common
knowledge, and nobody is arguing that pseudotails provide evidence that
we evolved from a tailed ancestor.
Luskin
then quotes medical journals that, although certainly reputable, are
not the typical sources for discussions of evolution. The articles are
appropriately tentative—“we raise the suspicion”—in suggesting that
pseudotails and “true tails” might actually be the same thing. If true,
this would imply that the accepted evolutionary explanation for true
tails should be abandoned, which would be significant, of course.
Luskin, however, makes no reference to the vast literature arguing with
considerable evidence for an evolutionary explanation for true tails.
Luskin
makes the best argument he can, of course, but it is piecemeal and
speculative. In the face of an overwhelming scientific consensus, he
finds a few lone critics with a few tentative comments and amazingly
ends up with “ample evidence,” to reject the received wisdom based on a
much more substantial body of evidence. “Another evolutionary icon has
fallen,” he concludes.
Klinghoffer and Luskin—and most everyone in the ID movement—employ the standard strategies of knowledge denial.
Cigarette companies used identical tactics for decades to deny that
smoking causes cancer. Today we see these tactics used to deny the
scientific consensus on the causes of climate change, the safety of vaccinating children, or the age of the earth.
The
strategy is always the same: toss irrelevant mud on the offending
argument—“he got his picture from Cracked.com.” Find a lonely voice and
enlarge its significance—“one expert thinks there are no true human
tails.” Draw certain conclusions from uncertain evidence. Pluck a pebble
from a mountain and pretend the mountain is gone. And never, ever,
engage the actual argument on its own terms: why is there bad design in
nature?
I am not trying to keep my debate with the ID “theorists”
alive, for there is no debate about evolution. The generally accepted
scientific ideas I presented remain alive and well and continue to guide
thinking about evolution. What I do want to do, however, is shine a
spotlight on the dangerous and slippery tools used by those who deny
scientific knowledge.
