Do embryos show evidence of evolution?
Welcome to Critical Thinking Scan, where we
look at how you can think about any faith-challenging
message and arrive at a biblical, logical
conclusion yourself.
I’m Patricia Engler and today, let’s begin
part 1 of 2 videos on how to think critically
about another top example textbooks cite as
“evidence for evolution,” which is similarities
across different kinds of embryos.
You might have heard of the famous forged
illustration by 19th-century biologist Ernst
Haeckel, which supposedly showed similarities
between embryos of different organisms including
fish, chickens and humans at various stages.
And Haeckel suggested that embryos reenact
evolution during their development; for example,
a human embryo would go through a fish stage,
amphibian stage and so on.
Now Haeckel himself admitted his drawings
were fraudulent, making embryos appear more
similar than they really are.
Even so, Haeckel’s drawings continued circulating
in textbooks until at least the 1990s, with
comparative embryology still being presented
as evidence for evolution today—even in
my own university textbooks.
Instead of touting Haeckel’s false claim
that whole embryos re-enact evolution, my
textbooks simply taught that similarities
between embryos are evidence of evolution,
or that parts of developing embryos reflect
their supposed evolutionary history.
For example, my evolution textbook talked
about “the similarity of many tetrapod vertebrate
embryos, all of which display pharyngeal clefts
(gill slits), a notochord [that’s a rod
of something like cartilage which becomes
the backbone in vertebrates], segmentation,
and paddlelike limb buds before the features
typical of their class or order become apparent.”
The book went on to admit that pharyngeal clefts,
which the book also called “gill slits,”
in mammals and reptiles “never acquire the
form typical of adult fishes.”
(That’s quite an understatement, as we’ll
see in a minute!)
But the text concluded, “Embryological similarities
provided Darwin with some of his most important
evidence of evolution, however, and they continue
to shed important light on how characteristics
have been transformed during evolution.”
So, is it true that these supposed similarities
in embryos are prime evidence for evolution?
Let’s think about it.
Check #1 of Critical Thinking is Check Scripture.
Genesis explains that God created living things
to reproduce according to their kinds.
So, while we wouldn’t be surprised if a
good Designer created many good designs—like
notochords—that apply to multiple types
of organisms, like all the different vertebrates,
we wouldn’t expect that one kind of vertebrate
could turn into another.
That would contradict a clear teaching of
Scripture, which is Check 2, Check the Challenge.
For Check 3, Check the Source, we can keep
in mind where this message is coming from.
Besides clearly starting from the worldview
foundation of man’s word instead of God’s,
my textbook happened to be quite anti-creation,
and even included an entire chapter 
attacking biblical creation.
So, we can expect the book will apply the
most evolutionary interpretations possible
to facts from observational science, which
will be important to keep in mind later in
the critical thinking process.
For Check 4, Check the Definitions, let’s
think about one of the main keywords here,
which is “similarities.”
How are we defining what counts as “similar?”
Do we mean the embryo’s body parts look
similar, or develop similar ways, or are expressed
by similar genes?
This is an important question, because as
we’ll continue to see in the next video,
how you define similarity affects which conclusions
you reach, and what kind of
evolutionary “family tree” you end up with.
Moving onto step 5, Check for Propaganda,
we can ask what aspects of this message’s
presentation make it sound persuasive.
For example, Haeckel used misleading propaganda by 
drawing embryos to look more similar than they were.
And today, textbooks sometimes use wording to make 
embryos sound more alike than they really are.
For instance, did you notice my textbook called
pharyngeal clefts “gill slits?”
Pharyngeal clefts are actually neither gills
nor slits; they’re folds of tissue near
an embryo’s head.
And human pharyngeal clefts don’t turn into
lungs, or have anything to do with the embryo’s
breathing; instead, they develop into different
structures of the head and neck.
But CALLING these tissue folds gill slits
anyway is a propaganda technique of association
to make humans seem more closely related to
fish than we really are.
We’ll move onto Check 6 in the next video,
but meanwhile, for more on how to think critically
about faith-challenging messages, you can
access my other CT Scan episodes packed with
tactics, tips and tools that helped me as
a Christian student in secular university.
Thank you for watching!
Hey, it’s Patricia, just wanting to let
you know that if you like these videos, are
on board to share the message of biblical
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